A manual of determinative mineralogy, with tables for the determination of Minerals by means of: I. Their physical characters; II. Blowpipe and chemical properties

Lewis, J. Volney (Joseph Volney), b. 1869 · 1921 · Historical

14

Public-domain full text preserved in the Mountain Man Mining Library. Original source: archive.org.

A Manual Of

Determinative Mineralogy

With Tables

A Manual Of Determinative Mineralogy

With Tables

For The Determination Of Minerals

By Means Of:

I. Their Physical Characters Ii. Blowpipe And Chemical Properties

By

J? Volney Lewis

Professor of Geology and Mineralogy in Rutgers University, State University of New Jersey

Third, Revised And Enlarged Edition

New York

John Wiley & Sons, Inc.

London: Chapman & Hall, Limited

Coptbight, 1912, 1915, 1921 By

J. Volney Lewis

Printed in U. S. A.

1/26 Press Of

BRAUNWORTH & CO., INC. BOOK MANUFACTURERS BROOKLYN, NtW YORK

Preface To The Third Edition

IN this, the third, edition, the blowpipe tables have been thoroughly revised and recast and a new classification of minerals based on their physical properties has been added. These two sets of tables are largely complementary, and cross-references have been inserted in order to facilitate their use as a check upon each other.

The blowpipe tables include about 355 minerals and the physical classification about 290. Species that have been omitted are very rare and, from the practical point of view, of no importance. The book is thus adapted to the requirements of the geologist and engineer, as well as the student.

The higher degree of accuracy attained in the determination of minerals by means of blowpipe and chemical tests is generally recognized, but in practice the necessary appliances are not always available. Furthermore, the experienced engineer and geologist may often save time by reference to the physical classification. Such tables have peculiar value for the student also, since they require close and accurate observation of streak, hardness, color, luster, form, and cleavage, and because of the emphasis they place on occurrence and mineral associates. By their use the student acquires a practical acquaintance with minerals that is of great value in sight-recognition.

The classification according to physical characters departs radically from the common practice in the construction of physical tables in that luster, so often a matter of uncertainty, has been entirely eliminated as a basis of classification. This keeps down the bulk of the tables somewhat, and to that extent facilitates their use, by avoiding excessive repetition.

Determinations based on physical characters often require confirmatory blowpipe tests, however, and, in the author's opinion, nothing can take the place of thorough drill for the student in blowpipe and chemical methods and in the use of tables based upon them. Chemical composition is the most fundamental property of minerals, and many species, particularly among the ores, can be determined with certainty only by means of chemical tests.

iv PREFACE TO THE THIRD EDITION

In the blowpipe tables the general plan of von Kobcll, as adapted and revised by Brush and Penfield, has been followed, but with much condensation and simplification of procedure and also with extensive rearrangement, especially among the nonmetallic minerals. Chemical formulas and descriptions of physical properties have been thoroughly revised and several new species have been added. In general blowpipe, or " dry," tests have been preferred to those made in the " wet " way.

A brief summary of physical mineralogy precedes the physical tables, and the text that precedes the blowpipe tables has been largely rewritten. Several new illustrations, drawn from photographs of the actual operations, are expected to reduce the labor of individual instruction in the details of laboratory technique. The classification of minerals according to crystallization has been revised and the glossary has been rewritten and enlarged. In the interest of efficiency these, together with the list of abbreviations and the table of chemical elements, have been placed at the end of the book.

It is intended that the use of the tables shall not only furnish a name by which a mineral may be called, but shall also lead the student to acquire a first-hand knowledge of what the mineral really is, both chemically and physically. The constant use of a good treatise on descriptive mineralogy to supplement the tables is strongly recommended. The instructions and precautions accompanying both the physical classification and the blowpipe tables will, it is hoped, prove adaptable and serviceable. They are intended to aid the student in the development of habits of neatness, orderliness, and accuracy, and at the same time to inculcate a certain respect for mineral specimens, which are so easily damaged or destroyed, but which cannot be reproduced.

Again I gratefully acknowledge my indebtedness to my fellow instructors in various parts of the country, of whose kindly criticism and helpful suggestions I have been glad to avail myself in the preparation of this revised edition.

J. Volney Lewis.

NEW BRUNSWICK, NEW JERSEY, December, 1920.

Contents

Page

Properties Of Minerals 1

Crystallization 1

Physical Properties . . . . 6

Chemical Properties 10

Physical Tables 12

General Classification 13

Determination By Blowpipe Tests 151

Apparatus 151

Reagents 154

Blowpipe Operations and Chemical Tests 156

Reactions of the Elements 174

Blowpipe Tables 191

Laboratory Records 193

General Table . 194

Minerals Classified According To Crystallization 266

Glossary 275

Abbreviations '. 285

Chemical Elements 286

Index.. . 287,

Determinative Mineralogy

Properties Of Minerals

Definition. — A mineral is a natural substance of definite chemical composition produced by inorganic processes and, with few exceptions, crystalline in structure. When crystallizing under favorable conditions minerals take the form of crystals bounded by plane surfaces, and all crystals of the same substance possess the same degree of symmetry and the same fixed angles between corresponding faces.

Many minerals are definite compounds only in the sense of varying between fixed limits, according to well-defined chemical principles (see Isomorphism, p. 11). A few like opal and chrysocolla, are amorphous, or noncrystalline, and widely variable in composition. Although included among minerals, such substances are, strictly speaking, not definite mineral species.

In contrast with the definiteness of minerals, rocks generally are aggregates of two or more minerals; some, however, like limestone and sandstone, are composed chiefly of one,

Crystallization

The Six Systems. — Crystals give outward expression to the symmetry of the internal molecular structure. All crystals may be grouped under six systems of crystallization. These are distinguished from one another by differences in symmetry, expressed in terras of directions and relative lengths of certain lines assumed through the center of the crystal and called crystallographic axes. Thus:

1. Isometric, having three equal axes at right angles to one another. (See Figs. 1 to 20.)

Properties Of Minerals

2. Tetragonal, having three axes at right angles, two of which are equal and the third shorter or longer. (Figs. 21 to 29.)

3. Orthorhombic, with three axes at right angles, all unequal. (Figs 30 to 37.)

4. Monoclinic, with three unequal axes, two inclined to each other and the third at right angles to these. (Figs. 38 to 44.)

5. Triclinic, three unequal axes, all inclined. (Figs. 45, 46.)

6. Hexagonal, having three equal axes in one plane and inclined at angles of 60 degrees to one another, with a fourth at right angles to these and shorter or longer. (Figs. 47 to 58.)

Twin crystals are symmetrical groups of two individuals (or more in case of repeated twinning), which may be simply in contact (contact twins, see Figs. 29 and 39) or may penetrate each other (penetration twins, see Figs. 12, 32, 33, and 43).

Fig. 1

Fig. 2.

FiG.~3.

Fig. 4.

Fig. 5.

Fig. 6.

Fig. 7.

Fig. 8.

Fig. 9.

Fig. 10.

Fig. 11.

Fig. 12.

ISOMETRIC CRYSTALS: Fig. 1, Octahedron (111); 2, Trisoctahedron (221); 3, Trapezohedron (211); 4, Hexoctahedron (321); 5, Cube, or hexahedron (100); 6, Tetrahexahedron (210); 7, Dodecahedron (110); 8, Combination of dodecahedron and trapezohedron; 9, Combination of cube and octahedron; 10, Combination of cube, octahedron, and dodecahedron; 11, Combination of octahedron and dodecahedron; 12, Twinned cubes (a penetration twin).

Crystallization

Fig. 13. Fig. 14.

Fig. 15.

Fig. 16.

Fig. 17.

Fig. 18.

Fig. 19.

Fig. 20.

ISOMETRIC CRYSTALS: Fig. 13, Tetrahedron (111); 14, Tristetrahedron (211); 15, Deltohedron (221); 16, Hextetrahedron (321); 17, Combination of tetrahedron and tristetrahedron (tetrahedrite) ; 18, Pyritohedron (210); 19, Diploid (321); 20, Combination of cube and pyritohedron (pyrite).

Fig. 21.

Fig. 22.

Fig. 23.

Fig. 24.

Fig. 25.

Fig. 26.

Fig. 27.

Fig. 28.

Fig. 29.

TETRAGONAL CRYSTALS: Fig. 21, Pyramid of the first order (111); 22, Pyramid of the second order (101); 23, Ditetragonal pyramid (212); 24, Ditetragonal prism (210); 25, Prism of the first order (110); 26, Prism of the second order (100) ; 27, Combination of first order prism and pyramid with second order prism (vesuvianite) ; 28, Combination of basal pinacoid with the same forms as Fig. 27 (vesuvianite) ; 29, Twin crystal of cassiterite (a contact twin).

Properties Of Minerals

Fig. 30.

Fig. 31.

Fig. 32.

Fig. 33.

Fig. 34.

Fig. 35.

Fig. 36.

Fig. 37.

ORTHORHOMBIC CRYSTALS: Fig. 30, Combination of pinacoids (100), (010), and (001); 31, Combination of basal and brachy pinacoids with prism (110) and macro dome (101) (staurolite) ; 32, 33, Penetration twins (staurolite) ; 34, Pyramid (111) (sulphur); 35, Combination of pyramids (111) and (113) (sulphur); 36, Combination of prism, pyramid, domes, and pinacoids (olivine); 37, Combination of prism, domes, and basal pinacoid (celestite).

\k/

Fig. 38. Fig. 39.

Fig. 40.

Fig. 41. Fig. 42.

MONOCLINIC CRYSTALS: Fig. 38, Hemipyramid (111), prism (110), and clino pinacoid (010), in combination (gypsum); 39, Contact twin (gypsum); 40, Combination of hemipyramids (111) (221), prism (110), and pinacoids (100), (010) (pyroxene) ; 41, Combination of same forms with basal pinacoid (001) (pyroxene); 42, Combination of prism (110), pinacoids (010) (001), and hemi-ortho domes (101) (201) (orthoclase).

Crystallization

Fig. 43.

Fig. 44.

Fig. 45.

Fig. 46.

MONOCLINIC CRYSTALS: Fig. 43, Penetration twin (orthoclase) ; 44, Prism (110), pinacoids (010) (001), and hemi-ortho dome (201) (orthoclase).

TRICLINIC CRYSTALS: Fig. 45, Combination of tetra-pyramids (111) (111), hemi-prisms, (110) (110), macro pinacoid (100), and macro dome (201) (axinite); 46, Combination of brachy pinacoid (010), basal pinacoid (001), hemi-prisms (110) (110), and tetra-pyramids (111) (HI) (albite),

Fig. 47.

Fig. 48.

Fig. 49.

Fig. 50.

Fig. 51.

Fig. 52.

Fig. 53.

Fig. 54.

HEXAGONAL CRYSTALS: Fig. 47, Pyramid (1011); 48, Dihexagonal pyramid (2131); 49, Prism (1010); 50, Dihexagonal prism (2130); 51, Combination of prism and pyramid; 52, Rhombohedron (1011) (calcite), 53, Rhombohedron (0221) (calcite); 54, Combination of the two preceding rhombohedrons (calcite).

Properties Of Minerals

Fig. 55.

Fig. 56.

Fig. 57.

Fig. 58.

HEXAGONAL CRYSTALS: Fig. 55, Scalenohedron (2131) (calcite); 56, Combination of scalenohedron and rhombohedron (calcite) ; 57, Combination of rhombohedron (Oll2) and prism (calcite); 58, Hemimorphic crystal (tourmaline).

In the absence of crystals, evidence of crystalline structure and symmetry may often be observed in the development of cleavage or parting in the broken material.

Physical Properties

Crystal aggregates, although lacking the definite symmetry of twin groups, may possess a high degree of regularity, as in radiating, globular, and plumose forms. In some aggregates the individuals are well-formed crystals at free ends or sides, but in many they are so closely crowded upon one another as to fill the whole space. This condition gives rise to coarse or fine granular texture and, where the individuals are microscopic in size, to dense masses.

Cleavage is the capacity possessed by many minerals for breaking with smooth planes parallel to certain actual or possible crystal faces, as in the basal cleavage of the micas, the rhombohedral cleavage of calcite, and the cubic cleavage of galena. Minerals that break with ease in such directions, like the examples named, yielding smooth lustrous faces, are said to have perfect cleavage. Inferior degrees are termed distinct, indistinct, imperfect, etc. Both the direction of cleavage and the ease with which it may be developed are fixed properties of the species, and hence important in determination.

Cleavage planes, in contrast with crystal faces, are commonly more or less splintery; and the simultaneous reflection of light from numerous small areas often reveals the presence of cleavage where no conspicuous flat surface is seen.

Parting resembles cleavage, but shows this important difference: ths capacity for breaking with smooth surfaces is limited to certain definite planes along which weakness has been developed by strain

Physical Properties 7

or by twinning lamellae. Hence one crystal may have parting while another of the same mineral may have none; and even where it is developed the portions between the parting planes do not possess the capacity for breaking in this manner.

Fracture is the term applied to breaking that, unlike cleavage and parting, does not produce smooth planes. Common forms are described as uneven, yielding a rough or irregular surface; conchoidal, breaking with curved surfaces, often with concentric markings like a shell; hackly, giving sharp, jagged surfaces, like broken metal; splintery, producing elongated splinters, commonly due to fibrous or columnar structure; and earthy, breaking like clay or chalk.

Hardness is resistance to abrasion, or scratching, and is commonly designated approximately by numbers, according to the scale of hardness devised by Mohs, as follows:

1. Talc 6. Orthoclase

2. Gypsum 7. Quartz

3. Calcite 8. Topaz

4. Fluorite 9. Corundum

5. Apatite 10. Diamond

Intermediate values are expressed as one-half (as 3J or 3.5, etc.). Closer determinations are seldom attempted. Approximate hardness can often be determined conveniently by noting the ease or difficulty with which a mineral scratches or is scratched by one of the following:

Thumb nail, 2£ Emery (wheel or paper), 8-9

Copper or silver coin, 3 Corundum or alundum (wheel, Knife blade, 5|-6 paper, or whetstone), 9

Window glass, 5|-6 Carborundum (wheel, etc.), 9J

File, 6J-7 Diamond (glazier's point), 10 Quartz or flint, 7

With practice hardness can be closely estimated with the knife alone. Rubbing on a fine-cut file is sometimes convenient; a soft mineral yields much powder and little noise, and vice versa. Hardness must be tested on a sound surface, and brittleness must not be confused with softness. Fibrous, scaly, granular, and pulverulent masses often crumble easily and seem much softer than they are. A few minerals show notable differences in hardness in different directions. Cyanite, the most striking example, is easily scratched with a knife lengthwise on the broad faces (H 4-5), but crosswise and on the thin edges it is harder than steel (H 6-7).

8 Properties Of Minerals

The ore minerals of the heavy metals — silver, copper, mercury, lead — are soft, mostly below 3. Sulphides, arsenides, and oxides of iron, nickel, and cobalt are relatively hard; other sulphides are mostly soft, as are also most carbonates, sulphates, and hydrous minerals. The very hard minerals are chiefly oxides and silicates and many of them contain aluminum.

Tenacity is the degree or character of cohesion. The distinctions commonly recognized are: sectile, may be cut with a knife, but slices are not malleable; malleable, flattens under the hammer; flexible, may be bent; elastic, springs back after bending; brittle, fragile, easily broken, the opposite of tough; friable, easily crumbled; pulverulent, powdery, with little or no cohesion, like chalk or clay.

Specific gravity is the weight of a substance compared with that of an equal volume of water; thus a mineral with specific gravity 3 is three times as heavy as water. The common methods of determining specific gravity are based on the fact that the loss in weight of a body immersed in water is the weight of an equal volume of water. Thus, if the weight of a mineral in air is a and its weight in water is w,

sp. gr. — . A porous texture, included or attached impurities, or alteration products will vitiate the result and may render it worth-

Minerals of fixed composition have a definite specific gravity. Many species in which one or more constituents are subject to isomorphous replacement, or substitution, show a corresponding range in specific gravity between certain limits. Whether the specific gravity of a mineral is high, low, or of intermediate value may generally be judged by the hand without weighing. Many of the methods for concentrating ores and other useful minerals are based on specific gravity.

Color is a f airly definite and fixed characteristic of minerals having metallic luster, but is very variable in most others. In some it varies with isomorphous variations in composition, in some it is due to minute colored inclusions, while in others it is possibly caused by a slight amount of some substance in solid solution. In general the cause of color in minerals is little understood. Some species change or lose their color under the influence of light, heat, rr-rays, and radium emanations; and, on the other hand, color appears under these influences in some minerals that were formerly colorless.

Mechanical color effects include play or change of color, irregular changes and flashes as the mineral is viewed in different directions; opalescence, a milky appearance, as in translucent opal; asterisrrij a

Physical Properties 9

star effect by reflected or transmitted light, due to structure planes or symmetrically arranged inclusions; iridescence, bands of prismatic colors due to cracks within or to a surface film produced by alteration or deposition; tarnish, an altered surface coating of different color from the fresh mineral.

Streak is the color of the finest powder of. a mineral, or of the mark it will make on a harder substance, such as unglazed porcelain, a clean whetstone, or a fine-cut file. The same result is obtained by scratching the mineral in the test for hardness, or by grinding a fragment in a mortar, or by crushing it to fine flour with a hammer on clean iron or steel. The color of the streak varies but little, even in those minerals that show great color variations in the mass.

Transparency, or diaphaneity. — A mineral is called transparent only when objects can be seen clearly through it, translucent if light is transmitted but objects are not seen, and opaque if no light passes, even through the thinnest edges. Semitransparent and semitranslucent express intermediate degrees. Many minerals that are commonly called opaque are translucent on thin edges and transparent in the thin sections that are prepared for microscopic study.

Luster is the surface appearance of an object, or the manner in which it reflects light. It is largely dependent on the character of the surface, but is modified by the degree of transparency and the refractive index of the substance. Several kinds of luster are commonly recognized. Metallic is the luster of metals and of some opaque minerals; submetallic and metalloidal refer to the same thing in subordinate degree. In mineralogy other types of luster are often referred to collectively as nonmetallic, but the following varieties should be readily recognized: vitreous, the luster of a broken surface of glass; adamantine, somewhat like oiled glass — the luster of the uncut diamond, zircon, cerusite, and other minerals of high refractive index; resinous, the luster of resin or sphalerite. Greasy, oily, pitchy, waxy, pearly, and silky are self-explaining terms. Degrees of intensity are designated, in the order of decreasing brilliance, as splendent, shining, glistening, glimmering. Dull signifies the absence of luster, as in chalk.

Fluorescence is the capacity possessed by some minerals for producing in sunlight or ultraviolet light a color different from their own and from that of the exciting light. Thus green or colorless fluorite commonly shows a bluish or purplish color in sunlight.

Phosphorescence is the glow induced in some minerals by the action of moderate heat, friction, mechanical or electrical stress, ordinary light, ultraviolet light, and radium emanations. The glow

10 Properties Of Minerals

may continue a few seconds or minutes after the removal of the cause. Nearly all specimens of some minerals (as diamond, willemite, kunzite, sphalerite) are phosphorescent. In others this property exists only in individual specimens or those from certain localities.

Taste. — Some minerals that are soluble in water have a characteristic taste, which may be salty, or saline, the taste of common salt (sodium chloride); alkaline, the. taste of soda (sodium bicarbonate); add, or sour, the taste of sulphuric acid; astringent, the taste of copperas (ferrous sulphate) ; sweetish astringent, the taste of alum (potassium-aluminum sulphate); cooling, the taste of niter (potassium nitrate) or potassium chlorate.

Odor. — Some minerals yield a characteristic odor when struck with a hammer, rubbed, breathed upon, or heated. These are described as arsenical, or alliaceous, like the odor of garlic (due to arsenic) ; seknious, or horseradish, the odor of decaying horseradish (selenium) ; sulphurous, the odor of burning sulphur (sulphur) ; fetid, the odor of rotten eggs (hydrogen sulphide) ; argillaceous, the odor of clay when breathed upon.

Feel is the sensation upon touching or handling minerals. Some that are very soft and greasy, soapy, or unctuous to the touch are contrasted with others that are notably rough, harsh, or meager.

Magnetism is most pronounced in magnetite, the only mineral that is strongly attracted by a common horseshoe magnet or a magnetized knife blade, which will pick up grains the size of a pea or larger. Pyrrhotite, or magnetic pyrites, and native platinum (alloyed with iron) are also commonly magnetic, and many specimens of hematite, ilmenite, chromite, and franklinite are weakly so and are attracted in minute particles. All iron-bearing minerals, even silicates with small percentages of iron, respond to powerful electromagnets; and magnetic properties are important in some methods of ore concentration.

Pyroelectricity is the capacity for developing electric charges at opposite ends or other parts of a crystal or crystalline fragment when gently heated. This property is most notable in hemimorphic minerals, such as tourmaline and calamine (electric calamine). The poles will attract minute bits of paper and other very light objects,

Chemical Properties

Composition. — Minerals are either uncombined elements, such as native gold (Au), copper (Cu), sulphur (S), or definite compounds of

Chemical Properties 11

the elements, as quartz (Si02), calcite (CaCOs), gypsum (CaSOi- 2H20). Chemical composition is the most fundamental property of minerals, and for purposes of description they are commonly classified on this basis. Thus the native elements are grouped together, and likewise the sulphides, oxides, carbonates, silicates, phosphates, etc. In determinative tables, such as appear in this book, the object is to group them according to such physical or chemical characters as will most facilitate the identification of unknown specimens.

Chemical analyses of minerals often vary from the formulas by which they are represented on account of one or more of the following causes: (1) Isomorphism (see below); (2) solid solution (e.g., pyrrhotite with excess S); (3) alteration or decomposition: (4) inclusion of crystals or particles of another mineral; (5) other minerals attached to the specimen or particles mixed in an aggregate, as gangue minerals in an ore.

Isomorphism is the capacity possessed by some minerals of analogous composition and similar crystal form of uniting in variable proportions to form homogeneous mixed crystals. In the group of the rhombohedral carbonate minerals, for example, calcite, which is essentially CaCOs, may also contain more or less magnesite, MgCOs, siderite, FeCOs, and rhodochrosite, MnCOs. This mingling of isomorphous minerals in the same crystal is equivalent to the substitution of magnesium, iron, and manganese for a part of the calcium in calcite, and may be expressed in the chemical formula thus: (Ca, Mg, Fe, Salts of different acids may also be isomorphous, as in the apatite group, which includes phosphates, arsenates, and vanadates. Most minerals are isomorphous mixtures and consequently subject, within limits, to variations in composition, specific gravity, color, and other properties, corresponding to the varying proportions of the interchangeable constituents.

Polymorphism, or pleomorphism, is the occurrence of two or more minerals of the same composition but differing in crystallization and in physical and optical properties. In some cases there are also pronounced differences in chemical properties. Native carbon is dimorphous, occurring as graphite and diamond ; titanium dioxide forms the three minerals, rutile, brookite, and octahedrite, and hence is said to be trimorphous. Allotropy and isomerism are chemical terms with somewhat similar meaning; thus there are four allo tropic forms of sulphur; the butyl alcohols and ordinary ether are isomeric.

Identification Of Minerals By Means Of Their Physical Properties

Preliminary Instructions and Precautions

If the crystal system can be determined, either from crystals or from cleavage, the crystal tables, pages 266 to 274, will often prove the most convenient means of identification.

Physical properties can be accurately determined only from fresh, homogeneous material, preferably crystalline. If the specimen is tarnished or decomposed at the surface a fresh fracture will often disclose unaltered material within.

Hardness of a mineral is estimated by comparison with a substance that is just hard enough to scratch it, remembering that substances of the same hardness will scratch each other slightly. Press a point or edge of known hardness against a smooth surface of the mineral and move it back and forth in the same line about one-eighth of an inch (3 mm.). Select an inconspicuous place and do not scratch the specimen more than necessary.

A " chalk " mark must not be mistaken for a true scratch. Brush away the powder and examine the smooth surface of the mineral. Rough or altered surfaces do not give reliable results. Alteration products are generally softer than the original mineral.

Powdery, earthy, and fibrous minerals generally appear to be both softer and lighter than they really are. On the other hand a soft mineral may appear harder than it really is on account of attached or intermingled grains of quartz or other hard substance.

A crystal or other mineral specimen should not be separated entirely from the matrix in which it is imbedded or the rock or mineral aggregate to which it is attached. Mode of occurrence and mineral associates are important aids to identification and shed much light on questions of origin.

Avoid breaking any specimen if there are enough fragments for tests. When it is necessary to break it, hold the specimen firmly in the hand, so as to catch the fragments in the palm, and strike a quick, sharp blow with a light hammer on a projecting edge or corner near the under surface. Do not break nor otherwise injure a good crystal, if it is possible to avoid it.

General Classification

(For abbreviations used in the tables, see page 285.)

Streak black or nearly so : SECTION PAGE

Mineral silver-white to steel-gray 1 14

Mineral dark gray, black, blue, or green 2 17

Mineral yellow, red, or brown 3 23

Streak silver- white to steel gray 4 26

Streak chalk-white, colorless, or pale colored:

Mineral white, colorless, or pale colored:

Distinct cleavage in one direction only 5 29

Distinct cleavage in two directions 6 34

Distinct cleavage in three or more directions . 7 39

No distinct cleavage 1 8 46

Mineral dark gray to black :

Distinct cleavage in one direction only 9 57

Distinct cleavage in two directions 10 61

Distinct cleavage in three or more directions. 11 64

No distinct cleavage l 12 69

Mineral yellow, red, or brown:

Distinct cleavage in one direction only 13 75

Distinct cleavage in two directions 14 80

Distinct cleavage in three or more directions .15 85

No distinct cleavage 1 16 92

Mineral green, blue, or violet:

Distinct cleavage in one direction only 17 104

Distinct cleavage in two directions 18 109

Distinct cleavage in three or more directions . 19 114

No distinct cleavage l 20 119

Streak yellow, red, or brown:

Mineral black or nearly so 21 128

Mineral yellow, red, or brown 22 135

Streak blue or green 23 145

1 A microscope, or even a pocket lens, will reveal cleavage in many fine

grained minerals. Without such aid, in specimens with fine granular, fibrous,

or dense texture, it may be impossible to determine whether or not the mineral has cleavage. Hence, if not found in this section of the tables, specimens of this character should be sought in the three preceding sections, disregarding altogether the question of cleavage.

Section 1

Streak black or nearly so; mineral silver- white to steel-gray. H.

G. 7.9-8.3 SYLVANITE AuAgTe4; Au 24.5%; Ag 13.4%. 2 Struct. — Branching aggregates, some like ancient script (graphic tellurium} ; bladed, columnar, granular; monoclinic crystals rare. Cleavage distinct one direction (010)'; brittle; fracture uneven.

Color silver-white to steel-gray, sometimes brassy tinge. Streak whitish, steel-gray. Luster metallic. Opaque. (See p. 206.)

In veins with gold, calaverite, sphalerite, pyrite, tetrahedrite.

2 G. 6.4-6.5 Bismuthinite (Bismuthine, Bismuth Glance}, Bi2S3; Bi 81.2%.

Struct. — Granular, foliated, fibrous; slender orthorhombic crystals rare. Cleavage perfect one direction lengthwise (010); slightly sectile.

Color light lead-gray, often yellowish tarnish. Streak dark lead-gray. Luster metallic. Opaque. (See p. 202.)

In veins with bismuth, chalcopyrite, cassiterite, gersdorffite, wolframite.

2 G. 5.5-6.0 JAMESONITE (Feather Ore), Pb2Sb2S5; Pb 50.8%; often some Fe.

3 Struct.— Acicular othorhombic crystals; fibrous, felted, compact; feathery appearance common. Cleavage distinct, one direction crosswise (001); brittle; fracture uneven.

Color steel-gray to dark lead-gray. Streak grayish black. Luster metallic . Opaque. (See p. 198.)

In veins with bournonite, galena, sphalerite, stibnite.

G. 8.3-8.4 KRENNERITE, AuAgTe4; Au 24.5%; Ag 13.4%.

Struct. — Small prismatic orthorhombic crystals striated lengthwise. Cleavage distinct crosswise (001); brittle; fracture uneven.

Color silver-white to brass-yellow. Streak steel-gray. Luster metallic. Opaque. (See p. 206.)

In veins with sylvanite, calaverite, molybdenite, pyrite, fluorite.

2 1 G. 8.3-8.5 HESSITE, Ag/Te; Ag 63.3%; often some Au. 3 Struct. — Fine grained to compact; isometric crystals rare. Cleavage none; somewhat sectile; fracture uneven.

Color steel-gray to lead-gray. Streak gray. Luster metallic. Opaque. (See p. 206.)

In veins with other tellurides, pyrite, chalcopyrite, fluorite.

G. 8.7-9.0 PETZITE, Ag3AuTe2; Ag 42%; Au 25.5%. 3 Struct. — Granular, compact. Cleavage none; slightly sectile to brittle; fracture uneven.

Color steel-gray to iron-black. Streak steel-gray. Luster metallic. Opaque. (See p. 206.)

In veins with hessite, calaverite, altaite, pyrite, siderite, quartz, gold.

Sec. 1] Physical Tables 15

H.

3 G. 8.1-8.2 Allaite, PbTe; Pb 62.3%; some Ag and Au.

Struct. — Compact; rarely isometric crystals. Cleavage three directions at 90° (100); sectile; fracture uneven.

Color tin-white, yellowish; tarnish bronze-yellow. Streak gray. Luster metallic. Opaque. (See p. 206.)

In veins with other tellurides, native tellurium, pyrite, galena, tetrahedrite.

4 G. 4.3-4.5 Stannite (Stannine, Tin Pyrites, Bellmetal Ore}, Cu2FeSnS4;

Sn 27.5%; Cu 29.5%; also Zn replacing iron up to 10%.

Struct. — Compact, granular, disseminated; small tetragonal crystals rare. Cleavage indistinct; brittle; fracture uneven.

Color steel-gray to iron-black; tarnish bluish; may be yellow from admixture of chalcopyrite. Streak black. Luster metallic. Opaque. (See p. 200.)

In veins with quartz, pyrite, scheelite, chalcopyrite, gold, silver, galena, sphalerite.

5 G. 7.0-7.4 LoUingite, FeAs2, passing into Fe3As4 (Leucopyrite) .

5£ Struct. — Granular, compact; orthorhombic crystals rare. Cleavage indistinct, one direction (001); brittle; fracture uneven.

Color silver-white to steel-gray; tarnish gray. Streak grayish black. Luster metallic. Opaque. (See p. 196.)

With arsenopyrite, siderite, cassiterite, hornblende, serpentine.

G. 6.0-6.3 COBALTITE (Cobalt Glance], CoAsS; Co 35.5%; As 45.2%;

some Fe.

Struct. — Isometric crystals (cubes, pyritohedrons, Figs. 5, 18, 20); granular, compact. Cleavage indistinct, three directions at 90° (100); brittle; fracture uneven.

Color silver- white to gray, sometimes reddish. Streak grayish black. Luster metallic. Opaque. (See p. 196.).

With silver, smaltite, niccolite, pyrrhotite, chalcopyrite; often with pink coating of erythrite.

G. 4.8-5.0 LINNAEITE (Cobalt Pyrites) Ni 12-43%; Co 11-45%. Struct. — Isometric crystals, commonly octahedrons (Fig. 1); granular. Cleavage indistinct, three directions at 90° (100); brittle; fracture uneven.

Color pale steel-gray, tarnish copper-red. Streak grayish black. Luster metallic. Opaque. (See p. 202.)

In veins with chalcopyrite, pyrrhotite, siderite, cobalt and nickel minerals.

G. 5.6-6.2 GERSDORFFITE, NiAsS; Ni 35.4%; often much Fe.

Struct. — Granular, lamellar; isometric-pyritohedral crystals. Cleavage indistinct, three directions at 90° (100); brittle; fracture uneven.

Color tin-white to steel-gray. Streak grayish black. Luster metallic. Opaque. (See p. 196.)

With ores of cobalt, nickel, silver, and copper.

16 Determinative Mineralogy [Sec. 1

H.

51 G. 5.9-6.2 ARSENOPYRITE (Arsenical Pyrites, Mispickel), FeAsS; As

6 46%.

Struct. — Granular, compact; orthorhombic crystals, like marcasite. Cleavage indistinct, two directions at 68° and 112° (110); brittle; fracture uneven.

Color silver-white to steel-gray. Streak grayish black. Luster metallic. Opaque. (See p. 196.)

With ores of gold, silver, lead, tin; with pyrite, chalcopyrite, sphalerite, smaltite.

G. 6.4-6.6 SMALTITE, CoAs2; Co 28.2%; some Ni and Fe. 6 Struct. — Granular, compact; isometric-pyritohedral crystals rare. Cleavage indistinct, four directions at 70|° and 109° (111); brittle; fracture uneven.

Color tin-white to steel-gray; often grayish tarnish and pink coating of erythrite. Streak grayish black. Luster metallic. Opaque. (See p. 196.) With niccolite, cobaltite, native bismuth and silver, proustite, barite, fluorite, calcite.

G. 6.4-6.6 CHLOANTHITE, NiAs2; Ni 28.1%; some Co and Fe. 6 Struct. — Granular, compact; isometric-pyritohedral crystals rare. Cleavage indistinct, four directions at 70| and 109|° (111); brittle; fracture uneven.

Color tin-white to steel-g'ray; often grayish tarnish and green coating of' annabergite. Streak grayish black. Luster metallic. Opaque. (See p. 196.)

With niccolite, cobaltite, proustite, native silver and bismuth, fluorite, barite, calcite.

6 G. 4.8-4.9 MARCASITE (White Iron Pyrites, White Iron}, FeS2; Fe 46.6%; S53.4%.

Struct. — Tabular orthorhombic crystals and twin groups, often cockscomb or spear-head forms (cockscomb pyrites, spearhead pyrites}; compact, stalactitic, rounded concretions. Cleavage indistinct, two directions at 75° and 105° (110); brittle; fracture uneven.

Color pale brass-yellow to almost white, tarnish deeper yellow to brown. Streak dark greenish to brownish black. Luster metallic. Opaque. (See p. 200.)

Alters readily on exposure to capillary melanterite and to limonite; much less stable than pyrite. With lead and zinc ores, pyrite, chalcopyrite, cinnabar; concretions in clay, shale, and coal.

6 G. 4.7-4.8 Braunite, 3Mn2O3.MnSiO3; Mn 64.4%.

Struct. — Granular; drusy crusts; minute tetragonal crystals, resembling octahedrons. Cleavage distinct, four directions at 70° and 110° (111); brittle; fracture uneven.

Color brownish black to steel-gray. Streak black, brownish black. Luster submetallic, greasy. Opaque. (See p. 208.)

With manganese minerals, magnetite, hematite, barite.

Sec. 2] Physical Tables 17

Section 2

Streak black or nearly so ; mineral dark gray, black, blue, or green. H.

0 Chalcocite, Melaconite, Argentite, Pyrolusite, Wad.

1 Black, powdery, earthy. (See pp. 17, 18, 19, 21.)

1 G. 4.7-4.8 MOLYBDENITE, MoS2; Mo 60.0%.

±5 Struct. — Scales, foliated masses, grains; tabular hexagonal crystals rare. Cleavage perfect, one direction (0001); thin flakes flexible; sectile; feels greasy.

Color bluish lead-gray. Streak grayish black, greenish on glazed paper or porcelain. Luster metallic. Opaque. (See p. 210.)

In granite, pegmatite, syenite, gneiss, with cassiterite, pyrrhotite, wolframite, tourmaline, topaz; in crystalline limestone with epidote, chal copyrite; in crystalline schists; in basic igneous rocks.

1 G. 1.9-2.3 GRAPHITE (Black Leak, Plumbago), C; often Fe, clay, etc.

2 Struct. — Foliated, scaly, granular, earthy; tabular hexagonal crystals rare. Cleavage perfect, one direction (0001); thin flakes flexible; sectile; feels greasy.

Color steel-gray to iron-black. Streak grayish black, shiny Luster metallic. Opaque. (See p. 210.)

In gneiss and mica schist; in crystalline limestone with garnet, spinel, wollastonite, pyroxene, amphibole; in pegmatite.

1 G. 1.0-1.8 ASPHALT (Asphaltum, Mineral Pitch), C, H, O, etc.

3 Struct. — Amorphous; solid or very viscous liquid. Cleavage none; brittle to flexible; fracture conchoidal.

Color black to brownish black. Streak brownish black. Luster pitchy, resinous, dull. Opaque. Bituminous odor; sticky when plastic. (See p. 212).

Massive deposits (" pitch lakes," etc.) and impregnating sedimentary strata.

1 G. 3.0-4.3 WAD (Bog Manganese), MnO2, H2O; often Fe, Si, Al, Ba, Co. 3 Mn up to 60%. Asbolan (Earthy Cobalt) contains Co to 25%.

Struct. — Earthy, porous (floating) to compact; sometimes globular; amorphous. Cleavage none; brittle; fracture earthy.

Color bluish or brownish black to dull black. Streak brownish black to black. Luster metallic to dull. Opaque. (See pp. 208, 250.)

In residual soil, clay, and swamp deposits, with psilomelane, pyrolusite, siderite, limonite.

1£ G. 4.6 COVELLITE (Covelline, Indigo Copper), CuS; Cu 66.4%.

2 Struct. — Disseminated, compact, in crusts; tabular hexagonal crystals rare. Cleavage perfect, one direction (0001); thin laminae flexible; brittle in mass; fracture uneven.

Color dark indigo-blue. Streak lead-gray to black. Luster submetallic, resinous, dull. Opaque. (See p. 200.)

In copper ores with bornite, chalcocite, chalcopyrite.

18 Determinative Mineralogy [Sec. 2

H.

2 G. 4.5-4.6 STIBNITE (Antimonite, Antimony Glance, Gray Antimony)

SbaSaj Sb71.8%.

Struct. — Long prismatic orthorhombic crystals, often bent or twisted; columnar, bladed, granular. Cleavage perfect, one direction lengthwise (010); crystals striated lengthwise; brittle, slightly sectile; fracture uneven; crystals slightly flexible.

Color lead-gray; tarnish black, sometimes iridescent. Streak dark leadgray. Luster metallic. Opaque. (See p. 198.)

In quartz veins in granite and gneiss with pyrite, sphalerite, galena, barite, cinnabar, realgar.

2 G. 6.4-6.5 Bismuthinite (Bismuthine, Bismuth Glance), Bi2S3; Bi 81.2%.

Struct. — Granular, foliated, fibrous; slender orthorhombic crystals rare. Cleavage perfect, one direction lengthwise (010); slightly sectile.

Color light lead-gray; often yellowish tarnish. Streak dark lead-gray. Luster metallic. Opaque. (See p. 2p2.)

In veins with bismuth, chalcopyrite, cassiterite, gersdorffite, wolframite.

2 G. 4.7-4.8 PYROLUSITE, MnO2; commonly a little H2O; Mn 63.2%. 2 1 Struct. — Columnar, acicular, fibrous, radial, dendritic, powdery; crystals pseudomorphous after manganite (orthorhombic). Cleavage none; brittle; fracture splintery, uneven.

Color black to steel-gray. Streak black, bluish black. Luster metallic, dull. Opaque. (See p. 208.)

In residual clays of limestone and slate with manganite, psilomelane, hematite, limonite, barite; dendritic in joint cracks.

2 G. 7.2-7.4 ARGENTITE (Silver Glance), AgaS; Ag 87.1%. Struct. — Compact; disseminated, incrusting; rough isometric crystals rare, often distorted. Cleavage indistinct; perfectly sectile, cuts like lead; fracture hackly.

Color lead-gray to black. Streak dark lead-gray, shiny. Luster metallic. Opaque. (See p. 200.)

In veins with silver, ruby silvers, stephanite, galena, smaltite, niccolite.

2 G. 6.2-6.3 STEPHANITE (Brittle Silver, Black Silver), Ag5SbS4; Ag 68.5%. 2% Struct. — Disseminated, compact; tabular or thick prismatic orthorhombic crystals, often pseudohexagonal. Cleavage imperfect; brittle; fracture uneven. '

Color dark lead-gray to iron-black. Streak iron-black. Luster metallic. Opaque. (See p. 198.)

In veins with other silver minerals, galena, barite.

2 G. 1.1-1.4 LIGNITE (Brown Coal), C, H, O, etc.; C 65-76%; "fixed" C 30-60%.

Struct. — Compact, amorphous; woody structure common. Cleavage none; fracture conchoidal, splintery; may crumble on exposure.

Color brownish black to black. Streak brown to brownish black. Luster dull; resinous (jet). Opaque. Burns with a smoky yellow flame. (See p. 212.)

Sec. 2] I'Hysical Tables 19

Plant remains commonly recognizable. Jet is a black compact variety that takes a polish. In stratified rocks, sands, clays, with pyrite and marcasite.

2 G. 1.2-1.5 BITUMINOUS COAL (Soft Coat), C, H, O, etc.; C 76-88%; "fixed" 2 C 48-73%.

Struct. — Amorphous; compact, lamellar, rarely fibrous. Cleavage none; brittle; cubical fracture conspicuous, sometimes conchoidal.

Color and streak black to brownish black. Luster pitchy, vitreous, dull. Opaque. Burns with a smoky yellow flame. (See p. 212.)

Sometimes shows plant remains; sometimes iridescent. Coking coal becomes pasty in the fire. Cannel coal is dull black, compact, structureless, with conchoidal fracture. Beds in stratified rocks, with pyrite and marcasite.

2 G. 1.3-1.7 ANTHRACITE COAL (Hard Coal), C 85-95%; volatile 1-5%. 2 Struct. — Amorphous, compact. Cleavage none; very brittle; fracture conchoidal.

Color iron-black to black, often iridescent. Streak black. Luster vitreous, submetallic. Opaque. Burns with pale feeble flame. (See p. 212.) Beds in stratified rocks, with pyrite and marcasite.

2 G. 6.0-6.2 POLYBASITE, Ag 62-72%; Cu 3-10%; some-

3 times As.

Struct. — Tabular six-sided monoclinic crystals with triangular markings on base; compact, disseminated. Cleavage imperfect, one direction (001); brittle; fracture uneven.

Color iron-black; in thin splinters cherry-red. Streak black. Luster metallic. Nearly opaque. (See p. 198.)

In veins with other silver minerals, galena, sphalerite; replacements in limestone.

2 G. 5.5-6.0 JAMESONITE (Feather Ore), Pb2Sb2S5; Pb 50.8%; often some Fe.

3 Struct. — Acicular orthorhombic crystals; fibrous, felted, compact; feathery appearance common. Cleavage distinct, one direction crosswise (001); brittle; fracture uneven.

Color steel-gray to dark lead-gray. Streak grayish black. Luster metallic. Opaque. (See p. 198.)

In veins with bournonite, galena, sphalerite, stibnite.

2-| G. 7.4-7.6 GALENA (Galenite, Lead Glance), PbS; Pb 86.6%; often Ag. Struct. — Cleavable masses, granular, compact; isometric crystals (commonly cubes, Fig. 5). Cleavage perfect, three directions at 90° (100); brittle. Color and streak dark lead-gray. Luster metallic. Opaque. (See p. 200.) In ore deposits with sphalerite, pyrite, chalcopyrite, barite, fluorite, calcite.

G. 5.5-5.8 CHALCOCITE (Copper Glance, Redruthite), Cu2S; Cu 79.8%; 3 sometimes Fe.

Struct. — Granular compact, disseminated; rarely in pseudohexagonal

orthorhombic crystals, deeply striated. Cleavage indistinct; rather brittle;

fracture conchoidal.

20 Determinative Mineralogy [Sec. 2

H.

Color dark lead-gray; tarnish dull black, blue, or green. May be coated with malachite (green) or azurite (blue). Streak dark gray to black, shiny. Luster metallic. Opaque. (See p. 200.)

In veins with pyrite, chalcopyrite, bornite, tetrahedrite, hematite, galena.

G. 5.7-5.9 BOURNONITE (Cogwheel Ore, Wheel Ore, Endellionite) , PbCuSbS3; 3 Pb42.5%; Cul3%.

Struct. — Fine grained, compact; thick tabular orthorhombic crystals or cross " cogwheel " twins. Cleavage indistinct; brittle; fracture uneven.

Color steel-gray to iron-black. Streak dark gray to black. Luster metallic. Opaque. (See p. 198.)

In veins with galena, sphalerite, tetrahedrite, siderite, stibnite, chalcocite.

2% G. 6.2-6.3 STROMEYERITE, AgCuS; Ag 53.1%; Cu 31.1%. 3 Struct. — Compact; rarely twinned pseudohexagonal orthorhombic crystals. Cleavage none; slightly sectile; fracture subconchoidal, uneven.

Color dark lead-gray. Streak dark lead-gray to black. Luster metallic. Opaque. (See p. 200.) v

In veins with copper and silver ores, argentite, proustite, chalcocite, tetrahedrite.

G. 8.3-8.5 HESSITE, Ag/Te; Ag 63.3%; often some Au. 3 Struct. — Fine grained to compact; isometric crystals rare. Cleavage none; somewhat sectile; fracture uneven.

Color steel-gray to lead-gray. Streak gray. Luster metallic. Opaque. (See p. 206.)

In veins with other tellurides, pyrite, chalcopyrite, fluorite.

G. 8.7-9.0 PETZITE, Ag3AuTe2; Ag 42%; Au 25.5%. 3 Struct. — Granular, compact. Cleavage none; slightly sectile to brittle; fracture uneven.

Color steel-gray to iron-black. Streak steel-gray. Luster metallic. Opaque. (See p. 206.)

In veins with hessite, calaverite, altaite, pyrite, siderite, quartz, gold.

3 G. 4.4-4.5 ENARGITE, Cu3AsS4; Cu 48.3%; As 19.1%; some Sb.

Struct. — Compact, columnar, granular; small prismatic orthorhombic

crystals rare. Cleavage distinct, two directions lengthwise (110) at 82° and

98°; brittle; fracture uneven.

Color and streak grayish black. Luster metallic. Opaque. (See p. 196.) In veins with pyrite, chalcopyrite, 'bornite, chalcocite, tennantite.

3 G. 6.1-6.2 PEARCEITE, Ag 55-60%.

Struct. — Tabular six-sided monoclinic crystals with triangular markings

on the base; compact, disseminated. Cleavage none; brittle; fracture con-

choidal.

Color and streak black. Luster metallic. Opaque. (See p. 196.) In silver ores with galena, chalcopyrite, quartz, calcite, siderite, barite.

Sec. 2] Physical Tables 21

H.

3 G. 4.4-5.1 TETRAHEDRITE (Gray Copper}, Cu3SbS3; often some Fe,

4 Zn, Pb, Ag, As. Cu 46.8%; Freibergite has Ag 3-15%. With increasing As grades into Tennantite, Cu3AsS3.

Struct. — Isometric-tetrahedral crystals (Figs. 13, 14, 17); granular, compact. Cleavage none; brittle; fracture uneven.

Color steel-gray to iron-black. Sometimes coated with brass-yellow chalcopyrite. Streak dark gray, black, reddish brown. Luster metallic. Opaque. (See p. 198.)

In veins with silver, lead, and copper ores,

3 G. 5.8-6.2 MELACONITE (Tenorite, Black Copper, Black Oxide of Copper],

4 CuO; Cu 79.8%.

Struct. — Earthy massive and powder (melaconite] . Thin scaly pseudohexagonal monoclinic crystals (tenorite) rare; Cleavage indistinct; crystals brittle; fracture uneven.

Color steel-gray to black. Streak black. Earthy varieties soil the fingers. Luster metallic; dull. Opaque. (See p. 204.)

Black coatings and crusts on native copper and various copper minerals.

3 G. 3.0-4.3 WAD (Bog Manganese), MnO2, H20; often Fe, Si, Al, Ba, Co.

4 Black, compact; H 1-6. (See p. 17.)

G. 4.2-4.4 MANGANITE, MnO-OH; Mn 62.4%; H2O 10.3%. 4 Struct. — Prismatic orthorhombic crystals striated lengthwise; often groups or bundles. Cleavage perfect, one direction lengthwise (010) ; rarely granular, stalactitic; brittle; fracture uneven.

Color steel-gray to iron-black. Streak reddish brown to black. Luster metallic, submetallic. Opaque. (See p. 208.)

Often altered to pyrolusite. With ores of manganese and iron; barite> calcite, siderite.

4 G. 4.3-4.5 Stannite (Stannine, Tin Pyrites, Bellmetal Ore], Cu2FeSnS<;

Sn 27.5%; Cu 29.5%; also Zn replacing iron up to 10%.

Struct. — Compact, granular, disseminated; small tetragonal crystals rare. Cleavage indistinct; brittle: fracture uneven.

Color steel-gray to iron-black; may be yellow from admixture of chalcopyrite; tarnish bluish. Streak black. Luster metallic. Opaque. (See p. 200.)

In veins with quartz, pyrite, scheelite, chalcopyrite, gold, silver, galena, sphalerite.

5 G. 7.2-7.5 WOLFRAMITE (Wolfram], grades into Ferberite, FeWO4, and Huebnerite, MnWO4; WO3 about 76%.

Struct. — Thick tabular, short columnar, and bladed monoclinic Crystals, resembling orthorhombic; cleavable, granular, compact. Cleavage perfect, one direction (010); brittle; fracture uneven.

22 DETERMINATIVE MINERALOGY [Ssc. 2

H.

Color dark gray, black, brownish black, reddish brown. Streak brownish black, black. Luster metallic, submetallic. Opaque. May be slightly magnetic. (See pp. 204, 222, 242.)

In veins in granite with cassiterite, quartz, mica, fluorite, apatite, scheelite, pyrite, galena, sphalerite; also in sands.

5 G. 4.5-5.0 ILMENITE (Menaccanite, Titanic Iron Ore), FeTiO3; Fe 36.8%.

6 Ti 31.6%; sometimes Mg.

Struct. — Thin plates, granular, compact, disseminated; pebbles, sand; thick tabular hexagonal-rhombohedral crystals. Cleavage none; sometimes partings; brittle; fracture conchoidal.

Color and streak iron-black, brownish black. Luster metallic, submetallic. Opaque. May be slightly magnetic. (See pp. 206, 210.)

Disseminated and masses in igneous rocks, gneiss, schist; with hematite, magnetite, titanite, apatite, rutile, quartz. Common in black sands.

5 G. 3.7-4.7 PSILOMELANE (Black Hematite}, MnO2, MnO, H2O, BaO, K2O.

6 Struct. — Compact, botryoidal, reniform, stalactitic; no crystals. Cleavage none; brittle; fracture conchoidal, uneven.'

Color iron-black, bluish black, steel-gray. May have sooty coating of pyrolusite or be in layers with it. Streak black, brownish black. Luster metallic, dull. Opaque. (See p. 208.)

With other manganese minerals, limonite, barite.

5 G. 3.0-4.3 WAD (Bog Manganese), MnO2. H2O; often Fe, Si, Al, Ba, Co.

6 Black, compact. H 1-6. (See p. 17.)

5J G. 9.0-9.7 URANINITE (Pitchblende), U03, UO2, Pb, Th, La, Y, He, Ra, etc.

Struct. — Botryoidal, granular, lamellar, compact; isometric crystals rare. Cleavage none; brittle; fracture conchoidal.

Color greenish or brownish black, pitch-black. Streak brownish black, grayish black, olive green. Luster pitch-like, submetallic, dull. Opaque. (See p. 210.)

With ores of silver, lead, copper, bismuth; also in pegmatites.

G. 4.0-4.1 Ilvaite (Lievrite),

6 Struct. — Prismatic orthorhombic crystals, striated lengthwise; columnar, compact. Cleavage indistinct, two directions at 90° (010) (001); brittle; fracture uneven.

Color black, greenish to brownish black; often softer yellowish altered coating. Streak black with greenish or brownish tinge. Luster submetallic, vitreous. Opaque. (See pp. 206, 220.)

In limestone and dolomite; with pyroxene, actinolite, iron minerals.

G. 4.9-5.2 MAGNETITE (Magnetic Iron Ore), FeFe,O4; Fe 72.4%;

6£ sometimes Mg, Mn, Ti.

Struct. — Granular, compact, lamellar, disseminated; sand; isometric crystals,, commonly octahedrons and dodecahedrons (Figs. 1, 7). Cleavage none; may have octahedral parting (111) four directions at 70|° and 109|°; brittle; fracture conchoidal, uneven.

Sec. 2, 3] Physical Tables 23

H.

Color iron-black. Streak black. Luster metallic. Opaque. Strongly attracted by magnet; may be natural magnet (lodestone). (See pp. 204, 206.)

Ore bodies and disseminated in igneous and metamorphic rocks; black sands; with hornblende, pyroxene, feldspars, chlorite, pyrite, apatite, ilmenite, zircon.

G. 5.1-5.2 FRANKLINITE, Fe 39-47%; Mn 6£ 10-20%; Zn 5.5-18.5%.

Struct. — Compact, granular, rounded disseminated grains; isometric

crystals (octahedrons, Fig. 1). Cleavage none; indistinct octahedral parting

(111) four directions at 70° and 109|°; brittle; fracture conchoidal, uneven.

Color iron-black. Streak black, brownish black, reddish brown. Luster

metallic, dull. Opaque. May be slightly magnetic. (See p. 208.)

In crystalline limestone (New Jersey) with zincite, willemite, rhodonite, tephroite.

6 G. 5.3-7.3 COLUMBITE, with Ta, grading into Tantalite,

(Fe, latter Ta2O6 up to 86%.

Struct. — Orthorhombic crystals, short, square, prismatic; granular, disseminated. Cleavage indistinct, one direction (100); brittle; fracture conchoidal. uneven.

Color iron-black, grayish and brownish black; may be iridescent. Streak dark red, brownish black, black. Luster submetallic, greasy, dull. Opaque. (See pp. 204, 210, 242, 264.)

In pegmatite with beryl, lepidolite, tourmaline, spodumene, cassiterite.

6 G. 4.7-4.8 Braunite, 3Mn2O3.MnSi03; Mn 64.4%.

6£ Struct. — Granular; drusy crusts; minute tetragonal crystals, resembling octahedrons. Cleavage distinct, four directions at 70° and 110° (111) ; brittle; fracture uneven.

Color brownish black to steel-gray. Streak black, brownish black. Luster submetallic, greasy. Opaque. (See p. 208.)

With manganese minerals, magnetite, hematite, barite.

SECTION 3 Streak black or nearly so; mineral yellow, red, or brown.

2 G. 6.0-6.2 POLYBASITE, Ag 62-72%; Cu 3-10%; some-

3 times As.

Struct. — Tabular six-sided monoclinic crystals with triangular markings on base; granular, compact, disseminated. Cleavage imperfect, one direction (001); brittle; fracture uneven.

Color iron-black; in thin splinters cherry-red. Streak black. Luster metallic. Nearly opaque. (See p. 198.)

In veins with other silver minerals, galena, sphalerite; replacements in limestone.

24 Determinative Mineralogy [Sec. 3

H.

G.9.0 CALAVERITE, Au 38-41%; Ag 2-4%.

Struct. — Compact; small monoclinic crystals rare. Cleavage none; brittle; fracture uneven.

Color light bronze-yellow. Streak yellowish gray. Luster metallic. Opaque. (See p. 206.)

In veins with gold, sylvanite, petzite, tetrahedrite, pyrite, fluorite.

2% G. 8.3-8.4 KRENNERITE, AuAgTe4; Au 24.5%; Ag 13.4%.

Struct. — Small prismatic orthorhombic crystals striated lengthwise. Cleavage distinct crosswise (001); brittle; fracture uneven.

Color silver-white to brass-yellow. Streak steel-gray. Luster metallic. Opaque. (See p. 206.)

In veins with sylvanite, calaverite, molybdenite, pyrite, fluorite.

3 G. 4.9-5.4 BORNITE (Erubescite, Purple Copper, Variegated Copper,

Peacock Ore, Horseflesh Ore), Cu5FeS4; Cu 63.3%.

Struct. — Compact, granular; isometric crystals (cubes) rare; Cleavage none: brittle; fracture uneven.

Color copper-red to bronze-brown; tarnish deep blue, purple, and variegated. Streak grayish black. Luster metallic. Opaque. (See p. 200.) In veins and ore deposits with other copper minerals, pyrite, siderite.

3 G. 8.1-8.2 AUaite, PbTe; Pb 62.3%.

Struct. — Compact; rarely isometric crystals. Cleavage three directions at 90° (100); sectile; fracture uneven.

Color tin-white, yellowish; tarnish bronze-yellow. Streak gray. Luster metallic. Opaque. (See p. 206.)

In veins with other tellurides, native tellurium, pyrite, galena, tetrahedrite.

3 G. 5.3-5.7 MILLERITE (Capillary Pyrites, Nickel Pyrites'), NiS; Ni 64.7%. 3 1 Struct. — Needle-like to hair-like crystals (hexagonal-rhombohedral) ;

fibrous crusts, compact. Cleavage rhombohedral, difficult to observe; brittle; slender crystals elastic; fracture splintery, uneven.

Color brass-yellow, bronze-yellow. Streak greenish black. Luster metallic. Opaque. (See p. 202.)

In cavities in hematite ore and limestone; with pyrrhotite, chalcopyrite, chloanthite, barite, fluorite, siderite.

G. 4.1-4.3 CHALCOPYRITE (Copper Pyrites, Yellow Copper Ore),

4 CuFeS2; Cu 34.5%.

Struct. — Compact, granular, disseminated; sometimes tetragonal crystals resembling tetrahedrons. Cleavage indistinct; brittle; fracture uneven.

Color brass-yellow, golden yellow; tarnish often iridescent or deep blue, purple, and black. Streak greenish black. Luster metallic. Opaque. (See p. 200.)

In schists, veins, and contact deposits with quartz, calcite, pyrite, bornite, chalcocite, galena, sphalerite.

Sec. 3] Physical Tables 25

H.

G. 4.6-5.1 PENTLANDITE Ni 18-40%.

4 Struct. — Granular, compact; isometric crystals rare. Cleavage distinct, four directions at 70° and 109|° (111); brittle; fracture uneven.

Color light bronze-yellow. Streak black. Luster metallic. Opaque. (See p. 202.)

,In nickel ores with chalcopyrite and pyrrhotite.

G. 4.5-4.6 PYRRHOTITE (Pyrrhotine, Magnetic Pyrites, Mundic), FeS; 4 1 S 36.4%; may have up to 3.5% additional S in solution.

Struct. — Compact, granular; tabular hexagonal crystals rare. Cleavage indistinct, one direction (0001); brittle; fracture uneven.

Color yellowish to brownish bronze; tarnish dark brown. Streak dark grayish black. Luster metallic. Opaque. Particles generally attracted by magnet. (See p. 200.)

In veins, schists, contacts, with pyrite, chalcopyrite, pentlandite, galena, apatite; accessory in basic igneous rocks; in magmatic segregations.

4 G. 4.3-4.5 Stannite (Tin Pyrites], Cu2FeSnS4; Sn 27.5%.

May be brass-yellow from admixture of chalcopyrite. (See p. 15.)

5 G. 7.2-7.5 WOLFRAMITE (Wolfram), grades into Per- 5% berite, FeWO4, and Huebnerite, MnWO4; WO3 about 76%.

Struct. — Thick tabular, short columnar, and bladed monoclinic crystals, resembling orthorhombic ; cleavable, granular, compact. Cleavage perfect, one direction (010) ; brittle; fracture uneven.

Color dark gray, black, brownish black, reddish brown. Streak brownish black, black. Luster metallic, submetallic. Opaque. May be slightly magnetic. (See pp. 204, 222, 242.)

In veins in granite with cassiterite, quartz, mica, fluorite, apatite, scheelite, pyrite, galena, sphalerite; also in sands.

5 G. 7.3-7.7 NICCOLITE (Copper Nickel), NiAs; Ni 43.9%; some Fe, Co, Sb, S. 5£ Struct. — Compact, disseminated; small hexagonal crystals rare. Cleavage none; brittle,; fracture uneven.

Color light copper-red; tarnish gray to blackish. May have coating of green (annabergite) . Streak brownish black. Luster metallic. Opaque. (See p. 196.)

With cobalt, nickel, and silver minerals, bismuth, arsenic, calcite.

G. 6.0-6.3 COBALTITE (Cobalt Glance), CoAsS; Co 35.5%; As 45.2%;

some Fe.

Struct. — Isometric crystals (cubes, pyritohedrons, Figs. 5, 18, 20); granular, compact. Cleavage indistinct, three directions at 90° (100); brittle; fracture uneven.

Color silver- white to gray, sometimes reddish. Streak grayish black. Luster metallic. Opaque. (See p. 196.)

With silver, smaltite, niccolite, pyrrhotite, chalcopyrite; often with pink coating of erythrite (cobalt bloom.)

26 Determinative Mineralogy [Sbc. 3, 4

H.

6 G. 4.9-5.2 PYRITE (Pyrites, Iron Pyrites, White Iron, Fool's Gold), FeS2;

6£ S 53.3%; Fe 46.7%; sometimes Ni, Co, Cu, Au.

Struct. — Isometric crystals, cubes, pyritohedrons, octahedrons (Figs. 1, 5, 18, 20), often striated; compact, granular, botryoidal, stalactitic. Cleavage none; brittle; fracture uneven.

Color pale to full brass-yellow; tarnish brown, variegated, sometimes iridescent. Streak greenish black, brownish black. Luster metallic. Opaque. (See p. 200.)

Lenticular bodies in schists; concretions, disseminated in clay, shale, coal; in veins with other sulphides; accessory in all kinds of rocks.

6 G. 4.8-4.9 MARCASITE (White Iron Pyrites, White Iron), FeS2; Fe 6£ 46.6%; S 53.4%.

Struct. — Tabular orthorhombic crystals and twin groups, often cockscomb or spear-head forms (cockscomb pyrites, spearhead pyrites)', compact, stalactitic, rounded concretions. Cleavage indistinct, two directions at 75° and 105° (110); brittle; fracture uneven.

Color pale brass-yellow to almost white; tarnish deeper yellow to brown. Streak dark greenish to brownish black. Luster metallic. Opaque. (See p. 200.)

Alters readily on exposure to capillary melanterite and to limonite; much less stable than pyrite. With lead and zinc ores, pyrite, chalcopyrite, cinnabar; concretions in clay, shale, and coal.

6 G. 4.7-4.8 Braunite, 3Mn2O3-MnSi03; Mn 64.4%.

Struct. — Granular, dnisy crusts; minute tetragonal crystals, resembling octahedrons. Cleavage distinct, four directions at 70° and 110° (111); brittle; fracture uneven.

Color brownish black to steel-gray. Streak black, brownish black. Luster submetallic, greasy. Opaque. (See p. 208.)

With manganese minerals, magnetite, hematite/ barite.

SECTION 4 Streak silver-white to steel-gray.

G. 13.6 Mercury (Native Mercury, Quicksilver), Hg; sometimes Ag. Struct. — Small liquid globules; isometric crystals (octahedrons) at —39° C.

Cleavage cubic; sp. g. of crystals 14.4.

Color tin-white. Luster metallic. Opaque. (See p. 202.)

With cinnabar and other mercury minerals and quartz, in shales, schists,

some hot springs.

G. 7.9-8.3 SYLVANTTE, AuAgTe4; Au 24.5% Ag 13.4%.

Struct. — Branching aggregates, some like ancient script (graphic tellurium) ; bladed, columnar, granular; monoclinic crystals rare;. Cleavage distinct, one direction (010) ; brittle; fracture uneven.

Sec. 4] Physical Tables 27

H.

Color silver- white to steel-grdy, sometimes brassy tinge. Streak whitish steel-gray. Luster metallic. Opaque. (See p. 206.)

In veins with gold, calaverite, sphalerite, pyrite, tetrahedrite.

2 G. 9.7-9.8 BISMUTH (Native Bismuth), Bi; of ten also As, S, Te. 2 Struct. — Laminated, granular, branching, disseminated; rarely distinct hexagonal-rhombohedral crystals. Cleavage distinct, one direction crosswise (0001); sectile; somewhat malleable.

Color silver-white, reddish; tarnish often brassy. Streak silver-white, shiny. Luster metallic. Opaque. (See p. 202.)

With ores of silver, cobalt, nickel, lead, zinc, tin, tungsten.

2 G. 6.1-6.3 Tellurium (Native Tellurium), Te; sometimes Se, Au, Fe. Struct. — Fine granular, columnar, compact; minute hexagonal-rhombohedral prisms. Cleavage distinct, three directions lengthwise at 60° and 120° (1010) ; somewhat brittle.

Color and streak tin-white. Luster metallic. Opaque. (See p. 206.) In veins with quartz, pyrite, gold.

G. 9.0 CALAVERITE, Au 38-41%; Ag

Struct. — Compact; small monoclinic crystals rare. Cleavage none; brittle; fracture uneven.

Color light bronze-yellow. Streak yellowish gray. Luster metallic. Opaque. (See p. 206.)

In veins with gold, sylvanite, petzite, tetrahedrite, pyrite, fluorite.

2% G. 8.3-8.4 KRENNERITE, AuAgTe4; Au 24.5%; Ag 13.4%.

Struct. — Small prismatic orthorhombic crystals striated lengthwise. Cleavage distinct, one direction crosswise (001); brittle; fracture uneven.

Color silver-white to brass-yellow. Streak steel-gray. Luster metallic. Opaque. (See p. 206.)

In veins with sylvanite, calaverite, molybdenite, pyrite, fluorite.

2% G. 10-12 SILVER (Native Silver), Ag; some Au, Cu. 3 Struct. — Grains, scales, plates, wire; isometric crystals commonly distorted. Cleavage none; malleable and ductile; fracture hackly.

Color silver-white; tarnish yellow, brown, black. Streak silver-white to light lead-gray, shiny. Luster metallic. Opaque. (See p. 202.)

In veins with silver, copper, and lead minerals, fluorite, calcite, barite, stibnite.

2% G. 8.3-8.5 HESSITE, A&Te; Ag 63.3%; often some Au. 3 Struct. — Fine grained to compact; isometric crystals rare. Cleavage none; somewhat sectile; fracture uneven.

Color steel-gray to lead-gray. Streak gray. Luster metallic. Opaque. (See p. 206.)

In veins with other tellurides, pyrite, chalcopyrite, fluorite.

28 Determinative Mineralogy (Sec. 4

H.

G. 8.7-9.0 PETZITE, AgsAuT; Ag 42%; Au 25.5%. 3 Struct. — Granular, compact. Cleavage none; slightly sectile to brittle; fracture uneven.

Color steel-gray to iron-black. Streak steel-gray. Luster metallic. Opaque. (See p. 206.)

In veins with hessite, calaverite, altaite, pyrite, siderite, quartz, gold.

G. 8.1-8.2 Altaite, PbTe; Pb 62.3%; some Ag and Au.

Struct. — Compact; rarely isometric crystals. Cleavage three directions at 90° (100); sectile; fracture uneven.

Color tin-white, yellowish; tarnish bronze-yellow. Streak gray. Luster metallic. Opaque. (See p. 206.)

In veins with other tellurides, native tellurium, pyrite, galena, tetrahedrite.

3 G. 13.7-14.1 Amalgam (Silver Amalgam), (Ag,Hg); Ag 27.5-95.8%. 3 1 Struct. — Plates, coatings, imbedded grains; rarely isometric crystals; Cleavage none; brittle to malleable; fracture conchoidal, uneven.

Color and streak silver-white. Luster metallic, brilliant. Opaque. (See p. 202.)

In veins with mercury and silver minerals.

3 G. 6.6-6.7 Antimony (Native Antimony), Sb; sometimes Ag, Fe, As. 3£ Struct. — Granular, cleavable, radiated, botryoidal; rarely hexagonalrhombohedral crystals. Cleavage distinct, one direction (0001); brittle; fracture uneven.

Color and streak tin-white to light steel-gray. Luster metallic. Opaque. (See p. 198.)

In veins with silver, arsenic, and antimony minerals.

3 G. 5.6-5.7 ARSENIC (Native Arsenic), As; often some Sb.

4 Struct. — Mammillary, concentric crusts, scaly, fine grained, compact; hexagonal-rhombohedral crystals rare. Cleavage distinct, one direction (0001); brittle; fracture uneven.

Color and streak tin-white, tarnishing soon to dark gray. Luster metallic. Opaque. (See p. 196.)

In veins with antimony minerals, ruby silver ores, realgar, orpiment, sphalerite.

G. 9.4-9.9 Dyscrasite (Antimonial Silver), Ag3Sb to Ag6Sb; Ag 73-84%.

Struct. — Compact, granular, incrusting; rarely columnar and tabular orthorhombic (pseudohexagonal) crystals. Cleavage distinct, three directions at 56°, 68°, and 124° (Oil) (001); sectile; fracture uneven.

Color silver- white to tin-white; tarnish yellow to black. Streak silverwhite, tin-white, shiny. Luster metallic. Opaque. (See p. 198.)

In veins with galena, arsenic, pyrargyrite, native silver, smaltite.

Sec. 4, 5] Physical Tables 29

H.

4 G. 14-19 PLATINUM (Native Platinum), Pt; Fe up to 15%, also Pd, Rh, 412 Ir, Os

Struct. — Grains, scales, lumps; rarely distorted isometric crystals; Cleavage none; malleable, ductile; fracture hackly.

Color tin-white, steel-gray; does not tarnish. Streak light steel-gray, shiny. Luster metallic. Opaque. May be magnetic. (See p. 210.) In placers with gold, chromite, iridium.

6 G. 22.6-22.8 Iridium (Native Iridium, Platiniridium) , Ir; some Pt, Pd, Rh.

7 Struct. — Angular grains; isometric crystals rare. Cleavage none; somewhat malleable; fracture hackly.

Color silver-white with yellowish tinge, gray on fracture. Streak light gray. Luster metallic. Opaque. (Seep. 210.) In placers with platinum, gold, chromite.

6 G. 18.9-21.2 Iridosmium (Iridosmine, Osmiridium), Ir, Os; also Rh, Pt, Ru.

7 Struct. — Scales, flattened grains; rarely hexagonal crystals. Cleavage distinct, one direction (0001); slightly malleable; fracture uneven.

Color tin-white to light steel-gray. Streak grayish. Luster metallic. Opaque. (See p. 210.)

In placers with platinum, gold, chromite

Section 5

Streak chalk- white, colorless, or pale colored; mineral white, colorless, or pale colored; distinct cleavage in one direction only.

0 G. 1.4-1.5 Sassolite (Native Boric Acid), H3BO3; B2O3 56.4%.

1 Struct. — Small pearly scales; rarely thin tabular triclinic crystals. Cleavage perfect, one direction (001); greasy feel; brittle.

Color white, grayish, yellowish. Streak white. Luster pearly. Translucent. Acid taste. (See p. 228.)

In hot lagoons, fumaroles, volcanic craters, lakes, springs.

1 G. 2.8-2.9 PYROPHYLLITE (Pencil Stone),

2 Struct. — Foliated, granular, fibrous, radial, compact; indistinct orthorhombic crystals rare. Cleavage perfect, one direction (001); fracture uneven, splintery; thin flakes flexible, not elastic; feel greasy.

Color white, apple-green, gray, yellow. Streak white. Luster Dearly to dull. Translucent to opaque. (See p. 256.)

In schistose rocks with cyanite, topaz, graphite, lazulite.

1 G. 2.5-2.8 TALC (Steatite, Soapstone, Potstone),

Struct. — Foliated, granular; fibrous (agolite); compact (soft, French

chalk; waxy, rensselaerite) ; indistinct tabular monoclinic crystals rare.

Cleavage perfect, one direction (001); fracture uneven; sectile; thin flakes

flexible, not elastic; greasy feel. H. sometimes 3-4.

30 Determinative Mineralogy [Sec. 5

H.

Color apple-green, gray, white. Streak white. Luster pearly, greasy. Transparent to opaque. (See pp. 236, 246, 256.)

In crystalline schists; with serpentine, dolomite, magnesite, chlorite, actinolite.

li G. 2.6-2.7 VIVIANITE (Blue Iron Earth], P2O5 28.3%. 2 Struct. — Radial fibrous, earthy; prismatic and tabular monoclinic crystals. Cleavage distinct, one direction (010); sectile; thin flakes flexible; fracture splintery, earthy.

Color blue, green, greenish black; colorless when fresh. Streak white, blue, greenish blue. Luster pearly on cleavage; vitreous, dull. Transparent to opaque. (See p. 218.)

In clay, marl, peat; in cavities of fossils; with limonite; in veins with pyrrhotite, pyrite, gold.

G. 2.3-2.4 GYPSUM (Selenite, Alabaster, Satin Spar), CaS04-2H2O. 2 Struct. — Granular, foliated, fibrous; earthy (gypsite); diamond-shaped monoclinic crystals with beveled edges (Figs. 38, 39). Cleavage perfect, one direction (010); two others less conspicuous (111) (100) at 90°, 66°, 114°; brittle; thin flakes flexible; fracture conchoidal, splintery.

Color white, colorless, gray, yellow, red. Streak white. Luster vitreous; pearly on (010); silky. Transparent to opaque. (See pp. 224, 226.)

Beds and masses with limestone, shale, clay, rock salt; near volcanic vents; with anhydrite, celestite, sulphur, calcite, aragonite.

2 G. 2.3-2.4 BRUCITE, sometimes Fe and Mn. 2% Struct. — Foliated, scaly; fibrous (nemalite) ; rarely broad tabular hexagonal-rhombohedral crystals. Cleavage perfect, one direction (0001); sectile; thin flakes and fibers flexible.

Color white, grayish, bluish, greenish. Streak white. Luster pearly, on cleavage; vitreous, waxy. Transparent to translucent. (See pp. 248, 252.)

With serpentine, dolomite, magnesite, chromite.

2 G. 1.7 BORAX (Tinkal), Na2B4O7-10H2O; B2O3 36.6%.

2 1 Struct. — Compact, earthy, incrusting; short columnar monoclinic crystals. Cleavage distinct, one direction (100); brittle; fracture conchoidal.

Color white, colorless, grayish, bluish, greenish. Streak white. Luster vitreous, greasy. Translucent to opaque. Sweetish alkaline taste. (See pp. 226, 228.)

In mud of alkaline lakes and marshes with halite, gypsum, colemanite.

2 G. 2.7-3.0 MUSCOVITE (Common or White Mica, Potash Mica. Isinglass),

3 often a little Na, Ca, Mg, Fe, and F. Struct. — Foliated, flaky; fine scaly to fibrous (sericite, damourite); dense

(pinite)', rarely distinct monoclinic (pseudohexagonal) crystals. Cleavage perfect, one direction (001) ; thin flakes tough, very elastic.

Color white, gray, yellowish, greenish, brownish. Streak white. Luster vitreous, pearly. Transparent to translucent. (See p. 236.)

In pegmatite, granite, gneiss, schists, contacts; with feldspars, quartz, tourmaline, beryl, garnet.

Sec. 5] Physical Tables 31

H.

2 G. 2.8-2.9 PHLOGOPITE (Amber Mica, Bronze Mica, Magnesia Mica),

3 some F and Fe.

Struct. — Plates, scales; prismatic or tabular monoclinic crystals with hexagonal or orthorhombic outline, commonly rough. Cleavage conspicuous, one direction (001); tough; laminae very elastic.

Color yellowish brown, brownish red, gray to green; rarely colorless. Streak white. Luster pearly, submetallic. Translucent to transparent. (See pp. 204, 236.)

Contacts in crystalline limestone; in serpentine; with pyroxene, amphibole, serpentine, graphite, apatite, corundum.

2 G. 2.8-2.9 LEPIDOLITE (Lithia Mica),

3 Li2O 3.8-5.8%.

Struct. — Foliated, scaly, compact; rarely monoclinic crystals, small tabular or prismatic. Cleavage perfect, one direction (001); laminae tough, elastic.

Color pink, lilac, yellowish, grayish white, white. Streak white. Luster pearly. Translucent. (See p. 236.)

In pegmatite with pink and green tourmaline, cassiterite, topaz, amblygonite, spodumene.

2 G. 2.8-2.9 Paragonite (Soda Mica),

3 Fine scaly masses, compact; strong pearly luster. Otherwise like muscovite, above. In schists with cyanite, staurolite, tourmaline, garnet, actinolite. (See p. 236.)

2 G. 2.7 THENARDITE, Na2SO4; Na2O 56.3%.

3 Struct. — Orthorhombic crystals, often cross twins; granular. Cleavage one direction (001) ; brittle; fracture uneven.

Color white to brownish. Streak white. Luster vitreous. Transparent to translucent. Soluble in water. (See p. 224.) About salt lakes and dry lake beds.

2% G. 2.7-2.8 Glauberite,

Struct. — Thick tabular monoclinic crystals; reniform, lamellar. Cleavage distinct, one direction (001); brittle; fracture conchoidal.

Color white, colorless, yellowish, grayish; white powdery coating forms on exposure. Streak white. Luster vitreous, greasy. Transparent to translucent. Taste slightly salty. (See p. 226.)

With halite, thenardite, mirabilite, hanksite, ulexite.

2$ G. 6.2-6.5 Leadhillite,

Struct. — Tabular monoclinic (pseudohexagonal) crystals and twins; compact, lamellar. Cleavage perfect, one direction (001) ; rather sectile; fracture conchoidal, rarely observable.

Color white, colorless, yellow, green, gray. Streak white. Luster pearly, adamantine. Transparent to translucent. (See p. 214.)

Twins and trillings like aragonite, but very heavy. Occurs sparingly with lead ores.

32 Determinative Mineralogy [Sec. 5

H.

gi G. 2.1-2.2 TRONA (Urao),

3 Struct. — In crusting; tabular or acicular monoclinic crystals. Cleavage one direction (100); brittle; fracture uneven.

Color white, colorless, yellowish, grayish. Streak white. Luster vitreous, pearly. Translucent. Alkaline taste. (See p. 224.)

Efflorescence; crusts about soda lakes; in beds with halite, glauberite, mirabilite, hanksite.

G. 2.7-2.8 Polyhalite, K2O 15.6,. 3 Struct. — Fibrous, lamellar, compact; monoclinic (?). Cleavage distinct, one direction; brittle; fracture splintery.

Color flesh to brick-red; yellowish red to white. Streak white, reddish to yellowish white. Luster greasy, pearly. Translucent to opaque. Taste weakly bitter and astringent. (See p. 226.) In beds of salt, gypsum, and clay.

3 G. 2.5-2.8 TALC (Steatite, Soapstone, Potstone),

4 Struct. — Foliated, granular; fibrous (agolite)] compact (soft, French chalk; waxy, rensselaerite) ; indistinct tabular monoclinic crystals rare. Cleavage perfect, one direction (001); fracture uneven; sectile; thin flakes flexible, not elastic; greasy feel. H. commonly 1-2

Color apple-green, gray, white. Streak white. Luster pearly, greasy. Transparent to opaque. (See pp. 236, 246, 256.)

In crystalline schists; with serpentine, dolomite, magnesite, chlorite, actinolite.

3£ G. 2.1-2.2 STILBITE (Desmine, a zeolite), 4 Struct. — Sheaf-like, radial, globular; tabular monoclinic crystals, commonly in twinned groups, orthorhombic in appearance. Cleavage distinct, one direction (010); brittle; fracture uneven.

Color white, grayish, yellowish, red to brown. Streak white. Luster vitreous; pearly on cleavage. Translucent. (See p. 234.)

Amygdules and veins in igneous rocks, chiefly basic; in metalliferous veins; with other zeolites, prehnite, datolite, pectolite, native copper, calcite, quartz, epidote, pyrite, chalcopyrite, chlorite.

G.2.2 HEULANDITE (a zeolite),

4 Struct. — Tabular monoclinic crystals, often look orthorhombic; dia-

mond-shaped, striated; foliated, globular, granular. Cleavage prominent, one direction (010) ; brittle; fracture uneven.

Color white, grayish, red, brown. Streak white. Luster vitreous; pearly on cleavage. Transparent to translucent. (See p. 234.) Occurrence and associations as for stilbite, above.

3£ G. 3.0-3.1 MARGARITE (Brittle Mica), H2CaAl4S2O12; some Fe, Na, K. 4 1 Struct. — Micaceous, scaly, granular; six-sided scales, plates (monoclinic). Cleavage perfect, one direction (001); flakes rather brittle, not elastic.

Color pink, grayish, white, yellowish. Streak white. Luster pearly on cleavage; vitreous. Translucent. (See pp. 236, 256.)

Coating or associated with corundum; also chlorite, spinel, emery, diaspore. APATITE. (See p. 52.)

Sec. 5] Physical Tables 33

4£ G. 2.3-2.4 APOPHYLLITE, a little F.

5 Struct. — Square, tabular, or cube-like tetragonal crystals; lamellar, granular, compact. Cleavage perfect, one direction (001); brittle; fracture uneven.

Color white, greenish, yellowish, reddish. Streak white. Luster vitreous; pearly on cleavage. Transparent to nearly opaque. (See p. 234.)

Amygdules and veins in igneous rocks, chiefly basic; in metalliferous veins; with zeolites, prehnite, datolite, pectolite, native copper, calcite, quartz, epidote, pyrite, chalcopyrite, chlorite.

DIOPSIDE. (See p. 36.)

6 G. 3.2-3.4 ZOISITE, often some Fe.

6 Struct. — Columnar, bladed, fibrous, compact; prismatic orthorhombic crystals striated lengthwise, without terminations. Cleavage conspicuous, one direction lengthwise (010); brittle; fracture uneven.

Color gray, yellowish brown, greenish; also red (thulile). Streak white. Luster vitreous; pearly on cleavage. Transparent to opaque. (See p. 246.)

In crystalline schists with hornblende, vesuvianite, cyanite, epidote, garnet, feldspars, quartz.

6 G. 3.2-3.3 SILLIMANITE (Fibrolite), Al2Si05, or

7 Struct. — Fibrous, columnar, radiating; slender orthorhombic crystals without terminations. Cleavage, one direction lengthwise (010); brittle; fracture splintery, uneven.

Color grayish white, hair-brown, greenish. Streak white. Luster vitreous, silky. Transparent to translucent. (See p. 260.)

In gneiss; in contacts of aluminous rocks; with andalusite, cordierite, garnets, corundum.

6 G. 3.3-3.5 DIASPORE, A1O.OH; Al 45%; sometimes Fe.

7 Struct. — Scaly, bladed, fibrous; columnar and tabular orthorhombic crystals rare. Cleavage distinct, one direction (010) ; brittle; fracture conchoidal.

Color white, grayish, greenish, hair-brown, yellow, colorless. Streak white. Luster vitreous; pearly on cleavage. Transparent to opaque. (See p. 260.)

With corundum, emery, dolomite, margarite, chlorite, magnetite.

6 G. 3.3-3.4 AXINITE, sometimes Mn, Fe, Mg.

7 Struct. — Tabular wedge-shaped triclinic crystals (Fig. 45) ; lamellar, granular. Cleavage distinct, one direction (010); brittle; fracture conchoidal.

Color clove-brown, yellow, greenish, grayish blue, gray. Streak white. Luster vitreous. Transparent to translucent. (See p. 242.) In veins with quartz, feldspars, hornblende, chlorite.

8 G. 3.4-3.6 Topaz,

Struct. — Prismatic orthorhombic crystals, many striated lengthwise; granular, pebbles, compact. Cleavage perfect, one direction crosswise (001); brittle; fracture conchoidal, uneven.

34 Determinative Mineralogy [Secs. 5, 6

H.

Color white, colorless, yellow, pink, bluish, greenish. Streak white. Luster vitreous. Transparent to opaque. (See p. 260.)

Veins in pegmatite, rhyolite, granite; contacts; placers; with tourmaline, cassiterite, apatite, fluorite, beryl, garnet.

Section 6

Streak chalk-white, colorless, or pale colored; mineral white, colorless, or pale colored; distinct cleavage two directions.

G. 3.7 STRONTIANITE (Strontian Spar) , SrCO3; SrO 70.1%; some-

4 times Ca.

Struct.— Chisel- or spear-shaped orthorhombic crystals, pseudohexagonal prisms; columnar, acicular, fibrous, divergent; granular, compact. Cleavage distinct, two directions at 63° and 117° (110); brittle; fracture uneven.

Color white, colorless, grayish, greenish, yellowish. Streak white. Luster vitreous, greasy. Transparent to translucent. (Seep. 246.)

In ore deposits with galena, barite, calcite, celestite, fluorite, pyrite; veins in limestone, chalk, marl.

4 G. 2.3-2.5 COLEMANITE (Pric&ite, Pandermite), 4 1 Struct. — Short prismatic monoclinic crystals; cleavable, granular, compact, incrusting. Cleavage distinct, two directions at 90° (010) (001) ; fracture uneven, conchoidal.

Color white, colorless, grayish, yellowish. Streak white. Luster vitreous, dull. Transparent to opaque. (See p. 228.)

Pandermite is compact, porcelain-like; priceite is loosely compacted, chalky. Beds in sediments with gypsum, celestite, quartz.

4 G. 2.2 Phillipsite (a zeolite), 5H2O; often Na.

4£ Struct. — Monoclinic penetration twins, often like orthorhombic or tetragonal; radial tufts or spheres. Cleavage, two directions at 90° (010) (001); brittle; fracture uneven.

Color white, reddish. Streak white. Luster vitreous. Translucent to opaque. (See p. 232.)

Amygdules and veins in igneous rocks, chiefly basic; in metalliferous veins; with other zeolites, prehnite, datolite, pectolite, native copper, calcite, quartz, epidote, pyrite, chalcopyrite, chlorite.

4£ G. 2.4-2.5 HARMOTOME (a zeolite), 4H2O; some Na and K.

Struct. — Penetration twins, etc. (monoclinic), like phillipsite, above, with cleavage, fracture, etc., the same.

Color white, grayish, yellow, red, brown. Streak white. Luster vitreous. Translucent. (See pp. 232, 244.)

Occurrence and associations as for phillipsite, above.

Sec. 6] Physical Tables 35

H.

4 G. 3.5-3.7 CYANITE (Kyantte, Disthene), Al2SiO6, or

5 Struct. — Long tabular or bladed triclinic crystals without terminations, may be curved or radiating. Cleavage pronounced, two directions lengthwise at 74° and 106° (100) (010); transverse parting (001) common; brittle; fracture splintery.

Color blue, white, gray, green, nearly black; often streaked. Streak white. Luster vitreous. Transparent to translucent. (See pp. 256, 260.)

Hardness lengthwise 4-5, crosswise 6-7. In gneiss and mica schist with staurolite, garnet, corundum

4 G. 4.4-4.6 XENOTIME, YPO4; also Er, Ce, Th, etc.

5 Struct. — Tetragonal crystals (prism, pyramid); compact, disseminated, rolled grains. Cleavage distinct, two directions at 90° (110); brittle; fracture uneven, splintery.

Color yellow, brown, red, pale gray. Streak pale brown, yellowish, reddish. Luster greasy, vitreous. Translucent to opaque. (See p. 256.)

Like zircon but softer. In pegmatite and granitic rocks with zircon, rutile; in sands.

4 G. 3.4-3.5 CALAMINE (Electric Calamine, Hemimorphite), 5 Zn 54.2%.

Struct. — Tabular orthorhombic-hemimorphic crystals, commonly divergent cockscomb groups; mammillary, stalactitic, granular. Cleavage, two directions lengthwise at 76° and 104° (110); brittle; fracture uneven, conchoidal.

Color white, colorless, yellowish, brownish, greenish, bluish. Streak white. Luster vitreous, adamantine, dull. Transparent to translucent. (See p. 252.)

In oxidized zinc ores, usually in limestone or clay, with smithsonite, cerusite, anglesite, galena, sphalerite, calcite, limonite.

G. 2.8-2.9 WOLLASTONITE (Tabular Spar, a pyroxene), CaSi03. 5 Struct. — Granular, fibrous, compact, cleavable; tabular monoclinic crystals. Cleavage distinct, two directions at 84£° and 95|° (100) (001); brittle; fracture uneven. ,

Color white, grayish, yellowish, reddish, brownish. Streak white. Luster vitreous, silky; pearly on cleavage. Translucent to opaque. (See p. 234.) In limestone contacts with pyroxene, tremolite, garnet, vesuvianite, epidote, graphite.

5 G. 2.2-2.3 NATROLITE (Needle Zeolite), 2H2O. 5 2 Struct. — Slender orthorhombic (pseudotetragonal) crystals; fibrous, radial, granular, compact. Cleavage, two directions lengthwise at 89° and 91° (110); brittle; fracture uneven.

Color white, colorless, grayish, yellowish, reddish. Streak white. Luster vitreous, silky. Transparent to translucent. (See p. 230.)

Amygdules and veins in igneous rocks, chiefly basic; in metalliferous veins; with other zeolites, prehnite, datolite, pectolite, native copper, calcite, quartz, epidote, pyrite, chalcopyrite, chlorite.

36 Determinative Mineralogy [Sec. 6

H.

5 G. 2.2-2.4 Scolecite (a zeolite), Struct. — Slender prismatic monoclinic twin crystals; fibrous, radiated, compact. Cleavage distinct, two directions lengthwise at 88° and 91|° (110) ; brittle; fracture splintery, uneven.

Color white, colorless. Streak white. Luster vitreous, silky. Transparent to opaque. (See p. 230.)

Occurrence and associations as for natrolite, on preceding page.

5 G. 2.9-3.1 TREMOLITE (Grammatite, an amphibole),

6 Struct. — Bladed, columnar, fibrous, compact; bladed monoclinic crystals without terminations; prism angle and cleavage (distinct, two directions lengthwise) at 56° and 124° (110); brittle; fracture uneven; small fibers flexible (asbestos) . Nephrite or jade, in part tremolite, is dense, compact, tough.

Color white to dark gray, yellowish, colorless. Streak white. Luster vitreous, silky, pearly. Transparent to opaque. (See p. 238.)

In limestone, dolomite, schist; common at contacts; with pyroxene, garnet, vesuvianite, epidote, wollastonite.

5 G. 3.2-3.6 DIOPSIDE (Malacolite, a pyroxene), some Fe.

6 Struct. — Prismatic monoclinic (pseudotetragonal) crystals, stout, terminated (Figs. 40, 41); lamellar, granular compact. Cleavage two directions lengthwise at 87° and 93° (110) sometimes distinct; often conspicuous transverse parting (001); brittle; fracture uneven.

Color white, colorless, grayish, green to black. Streak white, grayish, greenish. Luster vitreous, dull. Transparent to opaque. (See p. 240.)

In basic igneous rocks; in crystalline limestones with wernerite, vesuvianite garnet.

5 G. 3.1-3.3 ENSTATITE (a pyroxene), MgSi03; FeO up to 12%.

6 Struct. — Lamellar, columnar, fibrous, compact; prismatic orthorhombic crystals rare. Cleavage distinct, two directions at 88° and 92° (110) ; parting one direction (010), bisecting cleavage angle; brittle; fracture uneven.

Color grayish white, yellowish, greenish, to olive-green and brown. Streak white. Luster vitreous, pearly; submetallic, bronzy (bronzite). Translucent to opaque. (See pp. 240, 258.)

In basic igneous rocks (gabbro, peridotite) and serpentine.

5 G. 3.0-3.2 Anthophyllite (an amphibole), sometimes AI

6 (Gedrite).

Struct. — Lamellar, columnar, fibrous; prismatic orthorhombic crystals rare. Cleavage two directions lengthwise at 54|° and 125|° (110); brittle; fracture splintery; fine fibers flexible (asbestos).

Color gray, clove-brown, greenish to emerald. Streak white. Luster vitreous, pearly, silky, sometimes metalloidal. Translucent to opaque. (See pp. 222, 238, 258.)

In schists with talc, hornblende, chlorite, mica.

Sec. 6] Physical Tables 37

H.

6 G. 3.0-3.1 AMBLYGONITE, Li2O10.1%; often Na and sometimes OH.

Struct. — Cleavable, compact, columnar; triclinic crystals rare. Cleavage conspicuous, one direction (001), less distinct in another plane at 83° and 97° to this (100); brittle; fracture uneven.

Color white, pale gray, green, blue, yellow, brown. Streak white. Luster vitreous; pearly on (001). Translucent to opaque. Resembles feldspars, but heavier. (See p. 242.)

Rare in pegmatite with tourmaline, lepidolite, apatite, topaz.

6 G. 2.5-2.6 ORTHOCLASE (Potash Feldspar}, KAlSi3O8; K2O 16.9%; often Na.

Struct. — Cleavable, granular, disseminated grains; prismatic and tabular monoclinic crystals and twins (Figs. 42 to 44). Cleavage distinct, two directions at 90° (010) (001); brittle; fracture conchoidal, uneven.

Color white, red, gray, green, colorless. Streak white. Luster vitreous; often pearly on cleavage. Transparent to opaque. (See p. 238.)

In many igneous and metamorphic rocks; in veins and contacts; with quartz, other feldspars, mica, hornblende, pyroxene; in pegmatites with beryl, topaz, tourmaline. A dularia is transparent or opalescent (moonstone}. Sanidine is glassy, often transparent, in lavas. Sunstone, or aventurine feldspar, contains brilliant scales of hematite. Perthite and microperthite are interlaminated orthoclase and albite. Microcline and anorthoclase are triclinic and have cleavage angles not quite 90°, the former sometimes bright green (amazonstone, amazonite}, the latter with Na2O up to 8%. Hyalophane, with BaO 7-15%, likewise triclinic.

6 G. 2.6-2.8 PLAGIOCLASE (Soda-lime and Lime-soda Feldspars}, ranging from NaAlSi3O8 (ab) to CaAl2Si2O8 (an), often some K.

Comp. Sp. G. Comp. Sp. G.

Albite ab-ab6an! 2.62-2.64 Labradorite abiani-abian3 2.70-2.72 Oligoclase abeani-absani 2.65-2.67 Bytownite abian3-abian6 2.73-2.75 Andesine ab3ani-abiani 2.68-2.69 Anorthite abiane-an 2.75-2.76 Struct. — Lamellar, granular, disseminated; small triclinic crystals (Fig. 46). Cleavage distinct, two directions at 86°-86£° and 94-93° (001) (010); often striations on one cleavage; cleavage often curved; brittle; fracture uneven.

.Color white, colorless, gray, green, bluish, reddish; sometimes play of colors — blue, green, yellow, red. Streak white. Luster vitreous; often pearly on cleavage. Transparent to opaque, sometimes opalescent (moonstone}, or with bright reddish or yellowish reflections from included scales (aventurine feldspar, or sunstone}. (See p. 238.)

In igneous rocks, gneisses, schists, with other feldspars, quartz, mica, chlorite, zeolites; sometimes in veins.

6 G. 3.5-3.7 CYANITE (Kyanite, LHsthene}, Al2SiO5, or

7 Struct. — Long tabular or bladed triclinic crystals without terminations, may be curved or radiating. Cleavage pronounced, two directions length-

38 Determinative Mineralogy [Sec. 6

H.

wise at 74° and 106° (100) (010); transverse parting (001) common; brittle; fracture splintery.

Color blue, white, gray, green, nearly black, often streaked. Streak white. Luster vitreous. Transparent to translucent. (See pp. 256, 260.)

Hardness lengthwise 4-5, crosswise 6-7. In gneiss and mica schist with staurolite, garnet, corundum.

6 G. 3.1-3.2 SPODUMENE (a pyroxene), Li2O 8.4%; some Na.

7 Struct. — Cleavable, columnar, compact; rough prismatic or flattened monoclinic crystals, striated lengthwise. Cleavage conspicuous, two directions lengthwise at 87° and 93° (110); parting sometimes prominent, one direction (100), bisecting larger cleavage angle; brittle; fracture uneven, splintery.

Color white, gray, yellowish; emerald-green (hiddenite) ; pink to purple (kunzite). Streak white. Luster vitreous, pearly. Transparent to opaque. (See p. 240, 242.)

In pegmatites with tourmaline, lepidolite, beryl, amblygonite, cassiterite.

G. 3.1-3.2 ANDALUSITE (Chiastolite, Made}, Al2SiO5, or 7 1 Struct. — Columnar, granular, disseminated; rough orthorhombic prisms, nearly square. Cleavage distinct, two directions at 89° and 91° (110); brittle; fracture uneven.

Color white, pink, reddish brown, olive-green; sometimes black and white cross or checkered pattern on cross-fracture (chiastolite, or made). Streak white. Luster vitreous, dull. Translucent to opaque. (See p. 260.)

In slate, schists, and gneiss; with sillimanite, garnet, biotite, tourmaline, cordierite.

7£ G. 3.1 Lawsonite,

8 Struct. — Prismatic or tabular orthorhombic crystals; lenticular plates. Cleavage perfect, two directions at 90° (010) (001); brittle; fracture uneven.

Color pale blue, bluish gray, colorless; white or grayish spots due to alteration. Streak white. Luster virtuous, greasy. Transparent to opaque. (See p. 244.)

In schists with glaucophane, actinolite, margarite, epidote, garnet.

G. 3.5-3.8 CHRYSOBERYL (Cymophane), G1A12O4.

Struct. — Tabular orthorhombic crystals, heart-shaped or pseudohexagonal twins, disseminated plates. Cleavage two directions at 60° and 120° (Oil): brittle; fracture uneven, conchoidal.

Color yellowish green, deep green, greenish white, greenish brown, yellow. Alexandrite, the deep green variety, is red by gas or lamp light, cat's eye is yellowish green, opalescent. Streak white. Luster vitreous, greasy. Transparent to translucent. (See p. 260.)

In granite, gneiss, mica schist, placers; with beryl, garnet, tourmaline, sillimanite.

Sec. 7] Physical Tables 39

Section 7

Streak chalk-white, colorless, or pale colored; mineral white, colorless, or pale colored; distinct cleavage three or more directions.

H.

1£ G. 2.3-2.4 GYPSUM (Selenite, Alabaster, Satin Spar}, CaS04-2H2O.

2 Struct. — Granular, foliated, fibrous, earthy; diamond-shaped monoclinic

crystals with beveled edges (Figs. 38, 39). Cleavage perfect, one direction

(010); two others less conspicuous (111) (100) at 90°, 66°, 114°; brittle;

thin flakes flexible; fracture conchoidal, splintery.

Color white, colorless, gray, yellow, red. Streak white. Luster vitreous;

pearly on (010); silky. Transparent to opaque. (See pp. 224, 226.)

Beds and masses with limestone, shale, clay, rock salt; near volcanic vents;

with anhydrite, celestite, sulphur, calcite, aragonite.

2 G. 2.1-2.6 HALITE (Common Salt, Rock Salt), NaCl; Na 60.6%; often Ca and Mg.

Struct. — Granular, cleavable, compact; isometric crystals (cubes, Fig. 5); Cleavage distinct, three directions at 90° (100); brittle; fracture conchoidal. Color white, colorless, grayish, reddish, bluish. Streak white. Luster vitreous. Transparent to translucent. Taste salty. (See p. 224.)

Beds in sedimentary strata with gypsum, anhydrite, sylvite, calcite, clay, sand; in dry lakes; in brines. (Compare cryolite, p. 49.)

2 G. 1.9-2.0 SYLVITE, KC1; K 52.4%; sometimes Na.

2% Struct. — Granular, compact; isometric crystals (cubes, Fig. 5). Cleavage distinct, three directions at 90° (100); brittle; fracture conchoidal.

Color white, colorless, grayish, bluish, reddish. Streak white. Luster vitreous. Transparent to translucent. Taste salty, bitter; becomes damp in moist air. (See p. 224.)

In salt deposits; with halite, kainite, carnallite.

2% G. 2.0-2.2 KAINITE, KMgClSO4-3H2O; K 18.9%.

3 Struct. — Compact, fine granular; rarely tabular or prismatic monoclinic crystals. Cleavage distinct, three directions at 39£°, 101°, 140£° (100) (110); brittle; fracture uneven.

Color white, colorless, reddish. Streak white. Luster vitreous. Transparent to translucent. Taste salty, bitter, astringent. (See p. 224.) In beds with halite sylvite, gypsum, anhydrite.

2£ G. 4.3-4.6 BARITE (Barytes, Heavy Spar), BaSO4; sometimes Ca and Sr. 3 1 Struct. — Tabular and prismatic orthorhombic crystals, divergent groups; compact, lamellar, fibrous. Cleavage distinct, three directions at 78°, 90°, and 101|° (001) (110); brittle; fracture uneven.

Color white, colorless, light shades of yellow, brown, red, blue. Streak white. Luster vitreous, pearly. Transparent to opaque. (See p. 226.)

In veins with galena, sphalerite, fluorite, chalcopyrite; in limestones and residual clays with oxides of manganese and iron.

40 Determinative Mineralogy [Sec. 7

H.

3 G. 2.7 CALCITE (Gate Spar), CaC03; often Mg, Fe, Mn, sometimes Pb.

Struct. — Hexagonal-rhombohedral crystals, prismatic, scalenohedral, rhombohedral, tabular, or acicular in habit (Figs. 52 to 57); rarely twins; cleavable, granular, stalactitic, oolitic, earthy. Cleavage perfect, three directions at 75° and 105° (lOll); brittle; fracture conchodial, seldom observed.

Color white, colorless, pale shades of gray, yellow, red, green, blue, violet; brown to black when impure. Streak white. Luster vitreous, dull. Transparent to opaque. (See p. 246.)

Chief constituent of limestone, marble, chalk, calcareous marl; in veins with metallic ores, quartz, pyrite, zeolites. Dog tooth spar and nail head spar are suggestive crystal habits; Fontainebleau limestone, crystals containing much sand; satin spar, fibrous, silky; Iceland spar, transparent, suitable for optical uses; chalk, soft, white, yellowish, earthy; calcareous marl, soft, earthy, with clay; stalactites and stalagmites, cave deposits; calc sinter, calc tufa, travertine, deposits of springs or streams, porous, cavernous; thinolite, layers of yellow to brown cellular and skeleton crystals forming extensive tufa in dry lakes (N. W. Nevada), apparently tetragonal pseudomorphs.

3 G. 6.1-6.4 ANGLESITE (Lead Vitriol), PbSO4; Pb 68.3%.

Struct. — Orthorhombic crystals; granular, compact. Cleavage not conspicuous, three directions at 76°, 90°, and 104° (001) (110); brittle; fracture conchoidal.

Color white, colorless, gray, brown, green. Streak white. Luster adamantine, vitreous. Transparent to translucent. (See p. 214.)

In oxidized parts of ore deposits with lead, zinc, and iron minerals.

3 G. 2.9-3.0 ANHYDRITE (Anhydrous Gypsum), CaSO4.

3 1 Struct. — Granular, compact, fibrous, cleavable; rarely orthorhombic crystals. Cleavage distinct, three directions at 90° (001) (100) (010); brittle; fracture conchoidal.

Color white, grayish, bluish, reddish to brick-red. Streak white to grayish. Luster vitreous; pearly on (001). Translucent to opaque. (See p. 226.) In limestones, shales, salt deposits; with halite, gypsum, calcite.

3 G. 3.9-4.0 CELESTITE, SrSO4; sometimes Ca and Ba.

3 2 Struct. — Tabular or prismatic orthorhombic crystals (Fig. 37); fibrous, cleavable, rarely granular. Cleavage distinct, three directions at 76°, 90°, and 104° (001) (110); brittle; fracture uneven.

Color white, colorless, bluish, reddish. Streak white. Luster vitreous, pearly. Transparent to translucent. (See p. 226.)

In limestones and shales with gypsum, halite, sulphur, galena, aragonite.

G. 2.8-2.9 DOLOMITE, often Fe, Mn; much iron, Ankerite.

4 Struct. — Granular, cleavable, compact; hexagonal-rhombohedral crystals, faces often curved (pearl spar). Cleavage perfect, three directions at 74° and 106° (lOll); brittle; fracture conchoidal, uneven.

Sec. 7] Physical Tables 41

H.

Color white, colorless, gray, rod, green, brown, black. Streak white. Luster vitreous, pearly. Transparent to opaque. (See p. 246.)

Extensive strata as dolomitic limestone and marble; gangue with ores of lead, zinc, etc.; with serpentine, talc, gypsum, and ordinary limestone.

3 1 G. 3.8-3.9 SIDERITE (Spathic Iron, Chalybite, Clay Ironstone, Black 4 Band Ore) , FeCO3 ; Fe 48 .3 % .

Struct. — Granular, cleavable, compact; hexagonal-rhombohedral crystals, curved and saddle-shaped common. Cleavage perfect, three directions at 73° and 107° (lOll); brittle; fracture uneven.

Color gray, yellow, brown, black, sometimes white. Streak white, pale yellow. Luster vitreous, pearly, dull. Translucent to opaque. (See pp. 2 18, 248.)

In veins with silver minerals, pyrite and other sulphides, cryolite; beds and concretions in limestone, shale, and coal.

3£ G. 2.9-3.0 ARAGONITE (Flos Ferri), CaCO3; sometimes Sr and Pb. 4 Struct. — Chisel- or spear-shaped orthorhombic crystals, pseudohexagonal prisms; acicular, columnar, stalactitic, coral-like. Cleavage three directions at 64°, 90°, and 116°; (110) (010); brittle; fracture conchoidal.

Color white, gray, yellow, pale green, violet. Streak white. Luster vitreous, resinous. Transparent to translucent. (See p. 246.)

In gypsum beds, basalt, serpentine, beds of limonite and siderite; with celestite, sulphur, metallic sulphides, zeolites; constitutes some shells (pearly layers of many) and some coral.

G. 3.9.1 SPHALERITE (Blende, Zinc Blende, Jack, Black Jack, Rosin 4 Jack), ZnS; Zn 67%; may be replaced by Fe up to 18%.

Struct. — Cleavable masses, granular, compact, botryoidal; rounded isometric-tetrahedral crystals. Cleavage pronounced, six directions at 60°, 90°, and 120° (110); brittle; fracture conchoidal.

Color yellow, brown, red, green, black; rarely white or pale gray (cleiophane). Streak white, light to dark brown. Luster resinous, adamantine, submetallic. Transparent to opaque. (See pp. 200, 228, 250.)

Ore deposits and veins with galena, pyrite, chalcopyrite, fluorite, barite; also in limestone.

G. 2.2-2.3 LAUMONTITE (a zeolite),

4 Struct. — Radial, divergent, columnar; prismatic monoclinic crystals with

oblique terminations. Cleavage three directions lengthwise at 86°, 94°, and

137° (110) (010); brittle, friable; fracture uneven, earthy.

Color white, yellowish, grayish, reddish. Streak white. Luster vitreous,

pearly. Transparent to opaque. Becomes dull, opaque, and powdery on

exposure. (See p. 230.)

Amygdules and veins in igneous rocks, chiefly basic; in metalliferous

veins; with other zeolites, prehnite, datolite, pectolite, native copper, calcite,

quartz, epidote, pyrite, chalcopyrite, chlorite.

42 Determinative Mineralogy [Sec. 7

G. 3.4-3.6 RHODOCHROSITE (Dialogite), MnCO3; Mn 47.8%; some-

4f times Fe, Ca, Mg.

Struct. — Cleavable, granular, compact, botryoidal, incrusting; hexagonalrhombohedral crystals rare, commonly with curved faces. Cleavage conspicuous, three directions at 73° and 107° (lOll); brittle; fracture uneven.

Color reddish white, rose-red, dark red, brown; brown to black on exposure. Streak white. Luster vitreous, pearly. Transparent to translucent. (See p. 248.)

In veins with other manganese minerals, ores of silver, lead, and copper; pyrite.

G. 3.0-3.1 MAGNESITE, MgCO3; sometimes much Fe (Breunnerite) ; also Mn.

Struct. — Compact like unglazed porcelain, granular, cleavable; rarely hexagonal-rhombohedral crystals. Cleavage conspicuous, three directions at 72|° and 107|° (lOll); tough to brittle; fracture conchoidal.

Color white, yellowish, grayish, brown. Streak white. Luster vitreous, dull. Transparent to opaque. (See p. 248.)

Forming extensive beds; disseminated in talc and chlorite schists; veins in serpentine, dolomite, limestone; with gypsum.

4 G. 3.0-3.2 FLUORITE (Fluor Spar, Blue John), CaF2; F 48.9%; sometimes Cl.

Struct. — Isometric crystals (cubes, penetration twins, Figs. 5, 12); cleavable masses, granular, columnar. Cleavage perfect, four directions at 70|° and 109|° (111); brittle; fracture uneven.

Color violet, blue, green, yellow, colorless, brown. Streak white. Luster vitreous. Transparent to translucent. (See p. 226.)

Common in veins and contacts with galena, sphalerite, calcite, barite, cassiterite, apatite, topaz, lepidolite; in limestones; rare in igneous rocks.

4 G. 2.0-2.2 CHABAZITE (a zeolite), often K, Na, Ba,

5 Sr.

Struct. — Hexagonal-rhombohedral crystals (cube-like rhombohedrons), also modified forms, twins; compact. Cleavage distinct, three directions at 85° and 95° (lOll); brittle; fracture uneven.

Color white, yellow, flesh-red. Streak white. Luster vitreous. Transparent to translucent. (See p. 234.)

Amygdules and veins in igneous rocks, chiefly basic; in metalliferous veins; with other zeolites, prehnite, datolite, pectolite, native copper, calcite, quartz, epidote, pyrite, chalcopyrite, chlorite.

4 G. 3.5-3.7 CYANITE (Kyanite, Disthene), Al2SiO5, or

5 Struct. — Long tabular or bladed triclinic crystals without terminations, may be curved or radiating. Cleavage pronounced, two directions lengthwise at 74° and 106° (100) (010); transverse parting (001) common; brittle; fracture splintery.

Sec. 7] Physical Tables 43

H.

Color blue, white, gray, green, nearly black; often streaked. Streak white. Luster vitreous. Transparent to translucent. (See pp. 256, 260.)

Hardness lengthwise 4-5, crosswise 6-7. In gneiss and mica schist with staurolite, garnet, corundum.

4|- G. 5.9-6.1 SCHEELITE, CaWO4; WO380.6%; some Mo; sometimes Cu 5 (Cuproscheelite) .

Struct. — Small pyramidal tetragonal crystals resembling octahedrons, sometimes tabular; incrusting, granular, compact. Cleavage distinct, four directions at 49f , 80°, 100°, and 130° (111); brittle; fracture conchoidal, uneven.

Color white, yellow, brownish, greenish, reddish. Streak white to yellowish. Luster greasy, adamantine. Transparent to translucent. (See pp. 234, 254, 258.)

In veins and contacts with quartz, cassiterite, topaz, fluorite, apatite, molybdenite.

5 G. 4.3-4.5 SMITHSONITE (Dry Bone; Calamine, in England), ZnCO3; Zn52.1%.

Struct. — Mammillary, stalactitic, incrusting, cellular (dry bone); rarely small hexagonal-rhombohedral crystals. Cleavage distinct, three directions at 72° and 108° (lOll); brittle; fracture uneven, splintery.

Color white, grayish, colorless, greenish, blue, pink, brown. Streak white. Luster vitreous, adamantine, pearly, dull. Transparent to opaque. (See p. 248.)

In oxidized zinc ores, usually in limestone or clay, with smithsonite, cerusite, anglesite, galena, sphalerite, calcite, limonite.

5 G. 3.2-3.6 DIOPSIDE (Malacolite, a pyroxene), some Fe.

6 Struct. — Prismatic monoclinic (pseudotetragonal) crystals, stout, terminated (Figs. 40, 41); lamellar, granular, compact. Cleavage two directions lengthwise at 87° and 93° (110) sometimes distinct; often conspicuous transverse parting (001); brittle; fracture uneven.

Color white, colorless, grayish, green to black. Streak white, grayish, greenish. Luster vitreous, dull. Transparent to opaque. (See p. 240.)

In basic igneous rocks; in crystalline limestones with wernerite, vesuvianite, garnet.

5 G. 3.1-3.3 ENSTATITE (a pyroxene), MgSiO3; FeO up to 12%.

6 Struct. — Lamellar, columnar, fibrous, compact; prismatic orthorhombic crystals rare. Cleavage distinct, two directions at 88° and 92° (110); parting one direction (010), bisecting cleavage angle; brittle; fracture uneven.

Color grayish white, yellowish, greenish, to olive-green and brown. Streak white. Luster vitreous, pearly; submetallic, bronzy (bronzite). Translucent to opaque. (See pp. 240, 258.)

In basic igneous rocks (gabbro, peridotite) and serpentine.

44 Determinative Mineralogy [Sec. 7

H.

5 G. 2.5-2.6 NEPHELITE ( Nepheline, Elaeolite; a feldspathoid), NaAlSiO4;

6 also K (up to 7% K2O).

Struct, — Compact, disseminated grains; small hexagonal crystals rare. Cleavage distinct, three directions at 60° and 120° (lOlO); brittle; fracture conchoidal, uneven.

Color reddish, brownish, greenish, gray, white, colorless. Streak white. Luster greasy, vitreous. Transparent to opaque. (See p. 232.)

In lavas and granular igneous rocks with feldspars, sodalite, cancrinite, biotite, zircon, corundum; not with quartz.

5 G. 3.9-4.2 WILLEMITE, Zn2SiO4; Zn 58%; may contain Mn (Troostite);

6 some Fe.

Struct. — Compact, granular, disseminated grains; prismatic hexagonalrhombohedral crystals rare. Cleavage distinct, three directions at 60° and 120° (1120); brittle; fracture conchoidal, uneven.

Color yellow, green, red, brown, white. Streak white. Luster vitreous. Transparent to opaque. (See pp. 232, 252.)

In crystalline limestone with franklinite, zincite, rhodonite.

5 G. 2.6-2.8 WERNERITE (>ScopoZiie),

6 Struct. — Stout prismatic tetragonal crystals; compact, fibrous, granular. Cleavage three directions lengthwise at 45° and 90° (100) (110), not conspicuous; brittle; fracture conchoidal, uneven.

Color white, gray, greenish, bluish, reddish. Streak white. Luster vitreous, greasy. Translucent to opaque. (See pp. 234, 244.)

In crystalline limestones and schists with pyroxenes, amphiboles, apatite, garnet, biotite.

5 G. 2.4-2.5 CANCRINITE (a feldspathoid),

6 Struct. — Compact, lamellar, columnar, disseminated; prismatic hexagonal crystals rare. Cleavage distinct, three directions at 60° and 120° (10lO); brittle; fracture uneven.

Color white, gray, yellow, green, blue, reddish. Streak white. Luster vitreous, greasy, pearly. Transparent to translucent. (See p. 230.)

In granular igneous rocks with nephelite, sodalite, biotite, feldspars, titanite; not with quartz.

6 G. 3.5-3.7 CYANITE (Kyanite, Disthene), Al2Si05, or

7 Struct. — Long tabular or bladed triclinic crystals without terminations, may be curved or radiating. Cleavage pronounced, two directions lengthwise at 74° and 106° (100) (010); transverse parting (001) common; brittle; fracture splintery.

Color blue, white, gray, green, nearly black, often streaked. Streak white. Luster vitreous. Transparent to translucent. (See pp. 256, 260.)

Hardness lengthwise 4-5, crosswise 6-7. In gneiss and mica schist with Btaurolite, garnet, corundum.

Sec. 7] Physical Tables 45

6'. G. 3.5-3.7 GROSSULARITB (Essonitc, Hcssonile, Cinnamon Stone, a garnet), 7i often some Fe, Mg, Mn.

Struct. — Isometric crystals (dodecahedrons, trapezohedrons, Figs. 3, 7); granular, disseminated, lamellar, sand. Cleavage none; parting, sometimes distinct, six directions at 60°, 90°, and 120° (110); brittle; fracture conchoidal, uneven.

Color white, pink, yellow, brownish, pale green. Streak white. Luster vitreous. Transparent to translucent. (See p. 244.)

In limestone contacts with wollastonite, vesuvianite, diopside, scapolite.

7£ G. 2.9-3.0 PHENACITE, Gl2SiO4.

8 Struct. — Hexagonal-rhombohedral crystals, prismatic, lenticular; Cleavage distinct, three directions at 60° and 120° (1120); brittle; fracture conchoidal.

Color colorless, wine yellow, rose red, brown. Streak white. Luster vitreous. Transparent to translucent. (See p. 264.)

In pegmatite and metamorphic rocks with quartz, topaz, beryl, microcline, chrysoberyl.

9 G. 3.9-4.1 CORUNDUM (Adamantine Spar), A1203.

Struct. — Rough hexagonal-rhombohedral crystals, prismatic, pyramidal, tabular, tapering (barrel-shaped), often striated; lamellar, granular, compact. Cleavage none; often conspicuous parting, three directions at 86° and 94° (1011); sometimes transverse parting (0001); brittle, tough when compact; fracture uneven, conchoidal.

Color white, gray, brown to black; deep red (ruby); blue (sapphire); black from admixture of magnetite, hematite, or spinel (emery). Streak white. Luster vitreous, adamantine. Transparent to opaque. (See p. 260.)

In peridotite, gneiss, schist, syenite, crystalline limestone; with olivine, chlorite, serpentine, magnetite, spinel, vermiculite; cyanite, diaspore, muscovite.

10 G. 3.5 DIAMOND (Carbon), C.

Struct. — Isometric crystals (octahedron, hexoctahedron, Figs. 1, 4), usually with curved surfaces; rounded and irregular grains, pebbles, often with radial structure. Cleavage distinct, four directions at 70 2° and 109|° (111); brittle; fracture conchoidal.

Color white, colorless; pale shades of yellow, red, orange, green, blue, brown; occasionally black. Streak white. Luster adamantine, greasy. Transparent to opaque. Bort, rough rounded masses with radial or confused crystalline structure, without distinct cleavage; grayish to black; sp. g. 3.5. Carbonado, or black diamond, granular to compact, without cleavage; sp. g. 3.1-3.3. (See p. 264.)

In peridotite or serpentine; in sands, gravels, quartzite; with pyrope, magnetite, chromite, zircon, gold.

46 Determinative Mineralogy [Sec. 8

Section 8

Streak chalk-white, colorless, or pale colored; mineral white, colorless, or pale colored; no distinct cleavage.

H.

0 G. 2.6 KAOLINITE (Kaolin, China Clay}, H4Al2Si2O9.

1 Earthy, powdery; white, gray, yellowish, reddish; commonly soapy feel and plastic when wet. (See p. 47.)

0 G. 2.4-2.6 BAUXITE (Beauxite), mixture of A1O-OH and

1 Al 30-40%.

Clay-like, powdery, pisolitic; white, gray, yellowish, reddish. A mark made with heavy pressure on glass not easily rubbed off. (See p. 47.)

0 G. 2.7 CHALK (Marl, earthy, impure), CaCO3; a variety of calcite.

1 Powdery, clay-like, earthy; white, gray, yellowish; harsh feel. (See p. 40.)

0 G. 2.3-2.4 GYPSITE (earthy gypsum), CaSO4-2H2O.

1 Powdery, clay-like, earthy; white, gray yellowish. (See Gypsum, p. 30.)

0 G. 2.1-2.2 TRIPOLITE (Tripoli, Diatomaceous Earth, Infusorial Earth,

1 Diatomite) , SiO2-nH2O; the composition of opal. Powdery, earthy; a chalk-like opal; apparently soft, but particles scratch

glass; harsh feel. White, gray, yellowish. (See p. 48.)

0 G . 1 .7-1 .8 EPSOMITE (Epsom Salt) , MgSO4 7H2O .

1 Fibrous efflorescence, earthy powder; colorless, white, gray. Bitter saline taste. (See p. 49.)

0 G. 1.6-1.7 ULEXITE (Boronatrocalcite, Natronborocalcite), NaCaB5O9-8H2O.

1 Struct. — Fine fibrous masses (" cotton balls "), easily pulverized (monoclinic).

Color white. Streak white. Luster silky. Translucent. (See p. 228.) In dry lakes or about salt lakes with halite, gypsum, borax, glauberite.

1 G. 5.5-5.6 CERARGYRITE (Horn Silver), AgCl; Ag 75.3%; sometimes Hg, Struct. — Wax-like crusts, stalactitic, dendritic; isometric (cubic) crystals rare. Cleavage none; highly sectile; fracture conchoidal.

Color pearly gray, greenish, colorless; turns violet, brown, to black on exposure to light. Streak white, grayish, shiny. Luster waxy, greasy, resinous. Transparent to translucent. (See p. 216.)

In veins with other silver, minerals, calcitebarite, limonite.

Sec. 8] Physical Tables 47

H.

1 G. 2.5-3.2 ASBESTOS: Two varieties: (1) Chrysolite (fibrous serpen-

2 tine), H4Mg3Si2O9; (2) Fibrous amphiboles: anthophyllite, tremolite, actinolite,

crocidolite, NaFe"Fe'"(SiO3)

Struct. — Parallel flexible fibers; felted aggregates (mountain paper, mountain cork, mountain leather, mountain wood) .

Color white, gray, yellowish; also lavender-blue (crocidolite}. Luster silky, dull. Translucent to opaque. (See pp. 36, 62, 110, 122, 148.)

Chrysotile is chiefly short cross-fiber, perpendicular to walls of veins in serpentine, fibers fine silky, very flexible, tough; some slip-fiber parallel to walls. Amphibole asbestos, chiefly long fiber parallel to walls of veins in peridotite or pyroxenite, or chief constituent of latter, is dull, coarser fiber, little strength or toughness. The crocidolite variety is exceptional in most of these respects, being fine silky and tough.

1 G. 1.6 CARNALLITE, KMgCl3-6H2O; KC1 26.8%.

JJ Struct. — Granular, compact; orthorhombic (pseudohexagonal) crystals rare. Cleavage indistinct; brittle; fracture conchoidal.

Color white, grayish, brownish, reddish. Streak white. Luster vitreous, greasy. Transparent to translucent. Bitter taste; absorbs moisture. (See p. 224.)

With halite, kieserite, sylvite, boracite, anhydrite.

1 G. 6.4-6.5 Calomel (Horn Quicksilver), Hg2Cl2; Hg 84.9%.

2 Struct. — Coatings; small tetragonal crystals, tabular, pyramidal. Cleavage indistinct, two directions (100) at 90°; sectile; fracture conchoidal.

Color white, gray, yellowish to brown. Streak white, gray, yellowish. Luster adamantine. Translucent to opaque. (See p. 212.) In veins with cinnabar and mercury.

1 G. 2.4-2.6 KAOLINITE (Kaolin, China Clay, Porcelain Clay),

2 Struct. — Friable, clay-like, compact; minute scaly monoclinic crystals

(pseudohexagonal or pseudorthorhombic) rare; brittle; fracture earthy.

Color white, gray, yellowish, reddish. Streak white. Luster dull, pearly. Opaque to translucent. Generally plastic when moist. (See p. 256.)

With quartz, feldspar; largely from decomposition of latter; chief constituent of most clay. H alloy site, amorphous variety, little or no plasticity; translucent to transparent in water; infusible. Bentoniie, amorphous variety, brittle; soapy feel; very plastic when wet; absorbs three times its weight and seven times its volume of water; finally a glue-like paste. Fuller's earth, absorbent variety, decolorizes oils and other liquids.

1 G. 2.4-2.6 BAUXITE (Beauxite), mixture of colloidal A1O-OH (Diaspore)

3 and (Gibbsite)', often Fe, Si, Ca, Mg; Al 30-0%. Struct. — Amorphous, earthy, pisolitic, oolitic; brittle.

Color white, gray, yellow, red. Streak white. Luster dull. Opaque. A mark made with heavy pressure on glass not easily rubbed off. (See p. 256.)

Nodules and beds in clay or limestone, with iron oxides.

48 Determinative Mineralogy [Sec. 8

H.

1 G. 2.1-2.2 TRIPOLITE (Tripoli, Infusorial Earth, Diatomite, Diatoma- 3 ceous Earth), SiO2-nH2O; the composition of opal.

Struct. — Amorphous, porous, earthy, chalk-like; particles scratch glass; harsh feel; not plastic when wet.

Color white, gray, yellowish. Streak white. Luster dull. Opaque. (See p. 54.)

Associated and in part mingled with clay, sand, peat.

GYPSUM. (See p. 30.)

If G. 2.2-2.3 SODA NITER (Chile Saltpeter), NaNO3; N2O5 63.5%.

Struct. — Granular, crusts, efflorescences; rarely hexagonal -rhombohedral crystals, like calcite. Cleavage distinct, three directions at 73° and 106|° (1011); brittle, somewhat sectile; fracture conchoidal.

Color white, colorless, grayish, yellowish, brownish. Streak white. Luster yitreous. Transparent to translucent. Taste cool, salty; becomes damp in moist air. (See p. 224.)

Extensive deposits in some arid districts (Chile); with gypsum, sand, clay, guano.

1£ G. 1.4-1.5 MIRABILITE (Glauber Salt), Na2SO4 10H2O.

2 Struct. — Mealy efflorescences, fibrous crusts, powder; monoclinic crystals rare. Cleavage perfect, one direction (100); brittle; fracture conchoidal.

Color white, colorless, yellowish. Streak white. Luster vitreous. Transparent to opaque. Taste cool, saline. (See p. 224.) In dry lakes with halite, gypsum, clay, marl.

G. 2.0-2.1 SULPHUR (Brimstone), S; traces of Te, Se, As. 2 1 Struct. — Granular, fibrous, compact, earthy; reniform, stalactitic; incrusting; orthorhombic crystals, pyramidal (Figs. 34, 35), or tabular. Cleavage indistinct; brittle; fracture conchoidal.

Color yellow, greenish or reddish yellow, brown, gray. Streak white, pale yellow. Luster resinous, greasy, adamantine. Transparent to translucent. (See p. 212.)

In beds with gypsum; about vents of volcanoes and fumaroles; in oxidized parts of sulphide ores; with celestite, gypsum, calcite, aragonite.

2 G. 1.9 MELANTERITE (Copperas, Green Vitriol}, FeSO4-7H2O.

Struct. — Capillary, fibrous, compact, stalactitic, concretionary, powdery; monoclinic crystals rare. Cleavage inconspicuous, one direction crosswise (001); brittle; fracture conchoidal, earthy.

Color green, yellowish green, white; dull yellowish white on exposure. Streak white. Luster vitreous, dull. Transparent to translucent. Sweet astringent taste. (See p. 218.)

Oxidation product of iron sulphide minerals — marcasite, pyrite, chalcopyrite, pyrrhotite, etc.

2 G. 2.1-2.2 NITER (Saltpeter), KNO3; K2O 46.5%.

Struct. — Crusts, efflorescences, needle-like aggregates; rarely slender orthorhombic (pseudohexagonal) crystals. Cleavage distinct, two directions at 70° and 110° (Oil); brittle; fracture uneven.

Sec. 8] Physical Tables 49

H.

Color white, colorless, grayish. Streak white. Luster vitreous. Translucent. Taste cool, saline; remains dry in moist air. (See p. 226.) On rocks, walls, earth; in earth of some caves; in soil.

2 G. 1.0-2.0 SEPIOLITE (Meerschaum), H4Mg2Si3Oi0; sometimes Cu and Ni. 2% Struct. — Compact, nodular, earthy, clay-like; rarely fibrous; floats when dry. Cleavage none; brittle; fracture conchoidal, uneven; smooth feel; adheres to tongue.

Color white, grayish, yellowish. Streak white. Luster dull. Opaque. (See p. 232, 254.)

In peridotites and serpentine with magnesite, chlorite; masses in stratified earthy deposits.

2 G. 1.7-1.8 EPSOMITE (Epsom Salt), MgS04-7H2O.

2 Struct. — Granular, fibrous, capillary, incrusting, earthy; rarely prismatic orthorhombic crystals. Cleavage distinct, one direction (010); brittle; fracture conchoidal.

Color white, colorless, gray. Streak white. Luster vitreous, dull. Transparent to translucent. Taste bitter, salty. (See p. 224.)

On walls and floors of caves and mines with limestone, gypsum, serpentine, talc, magnesite.

2 G. 3.6-3.8 Hydrozincite (Zinc Bloom), Zn 60.8%. Struct. Earthy, compact, fibrous, incrusting, stalactitic. Cleavage none; brittle; fracture uneven, splintery.

Color white, gray, yellow. Streak white. Luster dull, pearly. Opaque. (See p. 248.)

With calamine, smithsonite, other secondary zinc minerals, and sphalerite.

2 G. 5.2-5.3 Senarmontite, Sb2O3; Sb 83.3%.

2% Struct. — Isometric crystals (octahedrons, Fig. 1); granular, incrusting; Cleavage indistinct; brittle; fracture uneven.

Color white, colorless, grayish. Streak white. Luster greasy, pearly. Transparent to translucent. (See p. 212.) With stibnite and other antimony minerals.

2 G. 2.6-2.7 Pharmacolite (Arsenic Bloom), HCaAsO4-2H2O. 2% Struct. — Fibrous, acicular, incrusting, powdery; small prismatic monoclinic crystals rare. Cleavage distinct, one direction lengthwise (010); sectile, thin flakes flexible; fracture uneven.

Color white, grayish; may be tinged red by Co or green by Ni. Streak white. Luster vitreous, pearly. Translucent to opaque. (See p. 228.) With arsenopyrite and arsenical ores of cobalt and silver.

2% G. 2.9-3.0 CRYOLITE, Na3AlF6; Na 32.8; Al 12.8%.

Struct. — Cleavable, granular, compact; rarely small monoclinic crystals, like cubes and octahedrons. Cleavage none; parting, often three directions at 88°, 90°, 92° (001) (110); brittle; fracture uneven.

;;0 Determinative Mineralogy [Sec. 8

Color white, colorless, brownish, reddish. Streak white. Luster vitreous, greasy; pearly on (001). Transparent to translucent. (See p. 226.)

Often resembles ice or paraffin. In veins with quartz, siderite, galena, sphalerite, pyrite, chalcopyrite, fluorite.

2 G. 2.0-2.2 DEWEYLITE (Gymnite), approx. EUMgSiOOsEkO; variable.

3 Struct. — Amorphous, like gum or resin. Cleavage none; brittle; often much cracked.

Color yellow, white, greenish, reddish. Streak white. Luster greasy, resinous. Translucent. (See pp. 232, 254.) In serpentine and crystalline limestone.

2% G. 1.0-1.1 AMBER (Succinite, Retinite), C2oH32O2.

3 Struct. — Amorphous, irregular lumps, grains. Cleavage none; brittle; fracture conchoidal; sometimes inclusions of insects, vegetable remains, liquids, minerals.

Color yellow, brownish yellow, brownish red, whitish. Streak white. Luster greasy, resinous. Transparent to translucent. Electrified by friction. (See p. 212.)

Fossil resin in clays, sands, coal beds, sedimentary rocks.

2% G. 2.3-2.4 GIBBSITE (Hydrargillite),

3 £ Struct. — Stalactitic, botryoidal, fibrous or scaly aggregates; tabular monoclinic (pseudohexagonal) crystals rare. Cleavage one direction (001), seldom observable; tough.

Color white, grayish, greenish, reddish. Streak white. Luster vitreous, dull, pearly. Translucent. (See p. 256.)

Chief constituent of some bauxite deposits; with corundum, natrolite, limonite.

3 CALCITE. (Seep. 40.)

3 G. 6.7-7.0 WULFENITE, PbMoO4; Pb 56.4%; sometimes Ca.

Struct. — Thin square tabular tetragonal crystals, sometimes acute pyramidal; granular. Cleavage indistinct; brittle; fracture conchoidal, uneven.

Color yellow, orange, olive-green, brown, yellowish gray, whitish. Streak white. Luster adamantine, resinous. Transparent* to translucent. (See p. 214.)

In oxidized parts of lead veins with galena, pyromorphite, vanadinite.

3 G. 1.8-1.9 ALLOPHANE, approx. Al2Si05-5H2O; variable.

Struct. — Amorphous, incrusting, stalactitic. Cleavage none; brittle; fracture conchoidal, earthy.

Color sky-blue, green, yellow, brown, colorless. Streak white. Luster vitreous, waxy. Translucent. (See p. 252.)

Resembles opal. In fissures and cavities in copper and iron mines; cavities in marls and limestones.

Sec. 8] Physical Tables 51

H.

3 G. 6.4-6.6 CERUSITE (White Lead, Ore), PbCO3; Pb 77.5%. 3 1 Struct. — Pseudohexagonal orthorhombic crystals, clusters, star-shaped groups; granular, fibrous, compact. Cleavage indistinct; brittle; fracture conchoidal.

Color white, gray, colorless, or yellow, brown, etc., from impurities. Streak white. Luster adamantine, greasy, silky. Transparent to translucent, (See p. 214.)

In oxidized parts of lead ores with lead, zinc, iron, and copper minerals.

ANHYDRITE, DOLOMITE (p. 40).

3 G. 2.5-2.6 SERPENTINE, H4Mg3Si2O9; commonly Fe, sometimes Ni.

4 Struct. — Massive, compact; fibrous (chrysolite, asbestos)', lamellar (mirmolite); columnar (picrolite) ; brittle; fibers flexible and tough; fracture conchoidal, splintery.

Color olive-green, blackish green, yellowish green, yellow; rarely white. Streak white. Luster greasy, waxy, silky.' Translucent to opaque. (See pp. 232, 254.)

Common alteration product of olivine rocks (pe-ridotites); in dolomitic limestone; with magnesite, talc, chromite, magnetite, corundum, platinum, diamond. Mixed with dolomite, calcite, or magnesite in a mottled or clouded green marble (verdantique, or ophicalcite) .

3 G. 4.3-4.4 WITHERITE, BaCO3; BaO 77.7%.

4 Struct. — Compact, granular, radial, fibrous, lamellar; pseudohexagonal orthorhombic crystals resembling quartz. Cleavage indistinct; brittle; fracture uneven.

Color white, grayish, yellowish. Streak white. Luster vitreous, greasy. Transparent to translucent. (See p. 226.)

In veins with galena, barite, fluorite, calcite.

31 G. 6.5-7.1 PYROMORPHITE (Green Lead Ore), Pb 76.3%; 4 P2O6 15.7%.

Struct. — Small prismatic hexagonal crystals, often rounded, barrelshaped, sometimes hollow; incrusting, reniform, disseminated. Cleavage none; brittle; fracture conchoidal, uneven.

Color green, yellow, brown, white, gray. Streak pale yellow, greenish yellow, white. Luster resinous, greasy, adamantine. Translucent to opaque. (See p. 214.)

In oxidized parts of lead veins with galena, cerusite, mimetite, barite, limonite.

G. 7.0-7.3 MIMETITE, Pb 69.5%; sometimes Ca and P. 4 Struct. — Prismatic, tabular, and barrel-shaped hexagonal crystals; globular, reniform, incrusting. Cleavage indistinct; brittle; fracture uneven. Color yellow, orange, brown, colorless. Streak white. Luster greasy, adamantine. Translucent. (See p. 214.)

In oxidized parts of lead ores with galena and pyromorphite.

52 Determinative Mineralogy [Sec. 8

H.

3£ G. 2.3-2.4 WAVELLITE, P2O6 34.5%; sometimes F.

4 Struct. — Radial fibrous, globular with crystalline surface, stalactitic; distinct orthorhombic crystals rare. Cleavage three directions at 73°, 90°, and 107° (101) (010); brittle; fracture uneven, conchoidal.

Color green, yellow, white, brown. Streak white. Luster vitreous, pearly. Translucent. (See pp. 252, 256.)

In clays and in veins and joint cracks of rocks; with oxides of iron and manganese, pyrits, actinolite, amblygonite.

3£ G. 2.6-2.8 ALUNITE (Alum Stone), K2O 11.4%; 4 A1203 37%.

Struct. — Compact, granular, fibrous, earthy; hexagonal-rhombohedral crystals, resembling cubes, rarely tabular. Cleavage indistinct, one direction (0001); brittle; fracture conchoidal, splintery, earthy.

Color white, grayish, reddish. Streak white. Luster vitreous, pearly. Transparent to opaque. (See pp. 248, 256.)

Veins and replacements in feldspathic rocks with quartz, kaolin, pyrite, opal.

G. 3.1-3.3 ScoRODiTE,FeAs04'2H2O.

4 Struct. — Pyramidal orthorhombic crystals, sometimes prismatic or tabular; botryoidal, fibrous, earthy, amorphous. Cleavage imperfect, two directions at 60° and 120° (120); brittle; fracture conchoidal, uneven.

Color pale green, bluish green, blackish green, blue, brown. Streak white, grayish, greenish. Luster vitreous, greasy. Translucent. (See p. 218.) With arsenopyrite, enargite, limonite, pyrite.

4 DOLOMITE (p. 40), MAGNESITE (p.~42).

4i G. 3.1-3.2 APATITE (Asparagus Stone), P205 42.3%; often

5 some Cl.

Struct. — Prismatic hexagonal crystals, sometimes tabular; granular, compact. Cleavage distinct to poor, one direction crosswise (0001); brittle; fracture conchoidal, uneven.

Color green, blue, violet, red, brown, white, colorless. Streak white. Luster vitreous, greasy. Transparent to opaque. (See pp. 228, 250.)

In crystalline limestone with graphite, fluorite, pyrrhotite; in igneous rocks (minute crystals); in magnetite ores; with fluorite in tin and tungsten ores; amorphous in stratified deposits with limestone and marl (phosphorite, phosphate rocks; phosphatic nodules).

G. 2.7-2.8 PECTOLITE, sometimes Mn. 5 Struct. — Fibrous, radiating, compact; rarely distinct monoclinic crystals. Cleavage two directions at 85° and 95° (100) (001) ; brittle; fracture splintery, uneven.

Color white, grayish, reddish. Streak white. Luster vitreous, silky. Translucent to opaque. (See p. 234.)

Amygdules and veins in igneous rocks, chiefly basic; in metalliferous veins; with zeolites, prehnite, datolite, native copper, calcite, quartz, epidoto, pyrite, ehalcopyrite, chlorite.

&Ec. 8] Physical Tables 53

H.

5 G. 4.3-4.5 SMITHSONITE (Dry Bone; Calamine, in England), ZnCO3; Zn 52.1%.

Struct. — Mammillary, stalactitic, incrusting; cellular (dry bone}; rarely small hexagonal-rhombohedral crystals. Cleavage distinct, three directions at 72° and 108° (lOll); brittle; fracture uneven, splintery.

Color white, grayish, colorless, greenish, blue, pink, brown. Streak white. Luster vitreous, adamantine, pearly, dull. Transparent to opaque. (See p. 248.)

In oxidized zinc ores, usually in limestone or clay, with smithsonite, cerusite, anglesite, galena, sphalerite, calcite, limonite.

5 G. 2.9-3.0 Datolite,

Struct. — Complex monoclinic crystals; granular, compact; botryoidal (botryolite). Cleavage none; brittle; fracture conchoidal, uneven.

Color greenish, colorless, yellowish, reddish, grayish. Streak white. Luster vitreous, greasy, dull. Transparent to opaque. (See p. 230.)

Amygdules and veins in igneous rocks, chiefly basic; metalliferous veins; with zeolites, prehnite, pectolite, native copper, calcite, quartz, epidote, pyrite, chalcopyrite, chlorite.

5 G. 2.2-2.3 ANALCITE (Analcime, a zeolite), Struct. — Isometric crystals (trapezohedrons, Fig. 3); granular, compact. Cleavage none; brittle; fracture uneven, conchoidal. Color white, colorless, grayish, greenish, yellowish, reddish. Streak white. Luster vitreous. Transparent to opaque. (See p. 232.)

Amygdules and veins in igneous rocks, chiefly basic; in metalliferous veins; with other zeolites, prehnite, pectolite, datolite, native copper, calcite, quartz, epidote, pyrite, chalcopyrite, chlorite. Sometimes primary constituent of igneous rocks.

5 G. 2.3-2.4 THOMSONITE (a zeolite), 5£ Struct. — Radial fibrous, columnar, spherical concretions, compact; rarely distinct prismatic orthorhombic crystals, striated lengthwise. Cleavage two directions lengthwise at 90° (100) (010); brittle; fracture uneven.

Color white, colorless, reddish, green, brown. Streak white. Luster vitreous, silky, pearly. Transparent to opaque. (See p. 230.)

Amygdules and veins in igneous rocks, chiefly basic; in metalliferous veins; with other zeolites, prehnite, datolite, pectolite, native copper, calcite, quartz, epidote, pyrite, chalcopyrite, chlorite.

5 G. 2.1-2.3 SODALITE (a feldspathoid),

6 Struct. — Compact, disseminated grains, nodular; isometric crystals (dodecahedrons) rare. Cleavage indistinct, six directions at 60°, 90°, and 120° (110); brittle; fracture conchoidal, uneven.

Color blue, gray, white, red, green. Streak white. Luster vitreous, greasy. Transparent to translucent. (See p. 230 -.)

In igneous rocks with nephelite, leucite, cancrinite; not with quartz.

54 Determinative Mineralogy [Sec. 8

H.

G. 2.4-2.5 LEUCITE (Amphigene; a feldspathoid), K2O 21.5%. 6 Struct. — Isometric crystals (trapezohedrons, Fig. 3), rounded disseminated

grains. Cleavage indistinct, brittle; fracture conchoidal.

Color white, gray, yellowish, reddish, colorless. Streak white. Luster vitreous, greasy. Translucent to opaque. (See p. 254.)

In lavas with sanidine, augite, nephelite, olivine; not with quartz.

G. 3.0-3.3 JADE, (Jadeite); or (Nephrite). 6£ Struct. — Very tough compact varieties of the amphiboles, tremolite and actinolite (nephrite), or of the pyroxene, jadeite; fracture splintery.

Color greenish, grayish, white, Streak white. Luster vitreous, waxy, dull. Translucent to opaque. (See pp. 36, 110.)

Rolled pebbles in clay; ancient or oriental utensils and art objects. Compare jade-like compact vesuvianite (calif ornite) , p. 101.

G. 2.1-2.2 OPAL, SiO2-nH2O; H2O 2-16%, chiefly 3-9%.

Struct. — Amorphous, botryoidal, reniform, stalactitic, earthy. Cleavage none; brittle; fracture conchoidal, conspicuous when compact.

Color white, yellow, red, brown, green, gray, blue, colorless; sometimes a rich play of colors (precious opal). Streak white. Luster vitreous, pearly, dull.. Transparent to opaque. (See pp. 256, 260, 264.)

In cavities and veins in igneous and sedimentary rocks. Precious opal, play of colors; fire opal, red, transparent or translucent; hyalite, colorless, transparent, like melted glass; common opal, translucent to opaque, greasy luster, many colors, but no play of colors — including milk opal, resin opal, jasp-opal, opal-agate; geyserite, siliceous sinter, porous, hot water deposit; tripolile, earthy, from leached limestone; diatomaceous earth, infusorial earth, chalk-like, clay-like, composed of diatom remains; wood opal, replacing fossil wood.

6 G. 2.8-3.0 Prehnite,

Struct. — Botryoidal, stalactitic, radial, fibrous; rounded groups of tabular orthorhombic crystals; distinct crystals rare. Cleavage indistinct, one direction (001); brittle; fracture uneven.

Color light green, oil-green, gray, white; often fading on exposure. Streak white. Luster vitreous, waxy. Transparent to translucent. (See pp. 234, 244.)

With zeolites, datolite, apophyllite, pectolite, native copper, calcite, quartz, epidote, chlorite — in igneous rocks, chiefly basic.

6 G. 3.1-3.2 CHONDRODITE, some Fe replaces Mg. Struct. — Rounded disseminated grains, compact; small complex monoclinic crystals rare. Cleavage sometimes distinct, one direction (001); brittle; fracture conchoidal, uneven.

Color brownish red, yellow, white. Streak white. Luster vitreous, greasy. Translucent to opaque. (See p. 252.)

In crystalline limestone with spinel, magnetite, pyroxene, vesuvianite, phlogopite, corundum.

Sec. 8] Physical Tables 55

a.

6 G. 6.8-7.1 CASSITERITE (Tinstone), SnO2; Sn78.6%; sometimes Fe

7 and Ta.

Struct. — Granular, disseminated; reniform with radiating fibrous structure (wood tin) ; sand and pebbles (stream tin) ; thick prismatic tetragonal crystals, knee-shaped twins common (Fig. 29). Cleavage indistinct; brittle; fracture uneven.

Color brown to black, rarely yellow, red, gray, white. Streak white, grayish, brownish. Luster adamantine, greasy, dull. Transparent to opaque. (See p. 262.)

In granite, gneiss, with wolframite, scheelite, molybdenite, tourmaline, fluorite, topaz, apatite, lepidolite; in pegmatites; in sands and gravels.

6£ G. 3.5-3.7 GROSSULARITE (Essonite, Hessonite, Cinnamon Stone', a garnet), often some Fe, Mg, Mn.

Struct. — Isometric crystals (dodecahedrons, trapezohedrons, Figs. 3, 7); granular, disseminated, lamellar, sand. Cleavage none; parting, seldom distinct, six directions at 60°, 90°, and 120° (110); brittle; fracture conchoidal, uneven.

Color white, pink, yellow, brownish, pale green. Streak white. Luster vitreous. Transparent to translucent. (See p. 244.)

In limestone contacts with wollastonite, vesuvianite, diopside, scapolite.

7 G. 2.65 QUARTZ (Rock Crystal), SiO2.

Struct. — Prismatic hexagonal crystals striated crosswise, commonly terminated by double rhombohedron (like hexagonal pyramid); granular, disseminated, compact. Cleavage indistinct; brittle; fracture conchoidal.

Color white, colorless, various shades (see varieties, below). Streak white. Luster vitreous, greasy. Transparent to opaque. (See p. 262.)

In igneous rocks, gneiss, schists, sand, sandstone, quartzite; common vein mineral with many metallic ores.

Varieties: Rock crystal, colorless, transparent; amethyst, purple, blue violet. (color destroyed by heat); rose quartz, pink to rose-red (fades on exposure); false topaz, citrine, clear yellow; smoky quartz, cairngorm, smoky yellow to black; milky quartz, milk-white, nearly opaque; cat's eye, opalescent from inclosed parallel fibers of asbestos; tiger eye, with lustrous yellow to brown parallel fibers; aventurine, glistening with inclosed scales (mica, hematite, etc.); ferruginous quartz, yellow, red, or brown from ferric oxides.

7 G. 2.6-2.64 CHALCEDONY (Agate, Flint, Hornstone), SiO2.

Struct.— Compact, botryoidal, mammillary, banded. Cleavage none; brittle to tough; fracture conchoidal.

Color white, grayish, brownish to black (see varieties below). Streak white. Luster waxy, vitreous to nearly dull. Translucent to opaque. (See p. 262.)

Lining or filling cavities (agate, etc.); concretions in chalk (flint) or limestone (chert, hornstone).

Varieties: Carnelian, sard, clear red to brownish red; chrysoprase, applegreen; plasma, leek-green to bright green; heliotrope, bloodstone, bright green

56 Determinative Mineralogy [Sbc. 8

with small spots of red; ayalc, variegated, generally banded; moss agate, with moss-like or tree-like inclusions; onyx, banded colors in flat planes; sardonyx, an onyx including layers of sard, or carnelian; siliceous sinter, cellular deposition from siliceous water (see also opal) ; flint, whitish, dull gray, smoky brown to black (nodules in chalk); chert, hornstone, like flint, but more brittle, with splintery fracture (in limestone); basanite, touchstone, compact, velvet-black; jasper, impure opaque, red, brown, or yellow from ferric oxides.

G. 2.3 Tridymite, SiO2.

Struct. — Minute thin tabular hexagonal crystals; twins common, groups resembling octahedron, fan-shaped, spherical rosettes. Cleavage indistinct; brittle; fracture conchoidal.

Color white or colorless. Luster vitreous, pearly. Transparent. ' (See p 264.)

In cavities in acid and intermediate volcanic rocks; with sanidine, hornblende, augite, hematite, opal.

7 G. 2.9-3.0 Boracite,

Struct. — Isometric-tetrahedral crystals (tetrahedron, cube), small, isolated; groups rare; granular. Cleavage indistinct; brittle; fracture conchoidal, uneven.

Color white, colorless, grayish, yellow, green. Streak white. Luster vitreous. Transparent to opaque. (See pp. 228, 242.)

Commonly disseminated glassy crystals with gypsum, anhydrite, halite, carnallite.

7 G. 3.0-3.2 TOURMALINE, R=Mg, Fe, Ca, Na, K, Li; often a little F.

Struct. — Prismatic hexagonal-rhombohedral crystals, hemimorphic, curved triangular in cross-section, striated lengthwise (Fig. 58); radiating, columnar, compact. Cleavage indistinct; brittle fracture uneven, conchoidal.

Color black (schorl), blue (indicolite), pink to red (rubellite), bro"wn, green; rarely white or colorless (achroite). Streak white. Luster vitreous, resinous. Transparent to opaque. (See pp. 222, 242, 258.) ;

In pegmatite, gneiss, mica schist, slate, gravels; common at contacts; with quartz, feldspars, beryl, topaz, cassiterite, fluorite.

7 G. 3.0 Danburite,

7 1 Struct. — Prismatic orthorhombic crystals, like topaz; disseminated. Cleavage indistinct; brittle; fracture uneven, conchoidal.

Color wine-yellow, yellowish white, yellowish brown. Streak white. Luster vitreous, greasy. Transparent to translucent. (See p. 242.)

With calcite, dolomite, mica, oligoclase, microcline, pyroxene, tourmaline.

G. 4.5-4.8 ZIRCON, ZrSiO4; ZrO 67.2%; commonly a little Fe.

Struct. — Square tetragonal crystals with prism and pyramid; irregular lumps, disseminated grains Cleavage indistinct; brittle; fracture uneven.

Secs. 8, 9] Physical Tables 57

H.

Color gray, brown, yellow, green; red transparent (hyacinth}', colorless or smoky (jargon}. Streak white. Luster adamantine, vitreous. Opaque to transparent. (See p. 262.)

Minute grains in feldspathic igneous rocks; rare in crystalline limestone, gneiss, schist; with magnetite, apatite, biotite, wollastonite, titanite; in placers with gold, corundum, spinel, garnet, monazite.

7£ G. 2.6-2.8 BERYL, a little H, sometimes Na, Li, Cs.

8 Struct. — Prismatic hexagonal crystals, often large, rough, and striated lengthwise (Fig. 49); columnar, granular, compact. Cleavage indistinct; brittle; fracture uneven, conchoidal.

Color bright green (emerald}, blue, greenish blue (aquamarine), yellow (golden beryl}, pink (rose beryl, morganite), colorless. Streak white. Luster vitreous. Transparent to translucent. (See pp. 244, 260.)

In pegmatite; less common in granite, mica schist, slate; in bituminous limestone. With topaz, tourmaline, garnet, chrysoberyl, rutile.

9 G. 3.9-4.1 CORUNDUM (Adamantine Spar}, A1203.

Struct. — Rough hexagonal-rhombohedral crystals, prismatic, pyramidal, tabular, tapering (barrel-shaped), often striated; lamellar, granular, compact. Cleavage none; often conspicuous parting, three directions at 86° and 94° (lOll); sometimes transverse parting (0001); brittle, tough when compact; fracture uneven, conchoidal.

Color white, gray, brown to black; deep red (ruby}; blue (sapphire}; black from admixture of magnetite, hematite, or spinel (emery}. Streak white. Luster vitreous, adamantine. Transparent to opaque. (See p. 260.)

In peridotite, gneiss, schist, syenite, crystalline limestone; with olivine, chlorite, serpentine, magnetite, spinel, vermiculite; cyanite, diaspore, muscovite.

Section 9

Streak chalk- white, colorless, or pale colored; mineral dark gray to black; distinct cleavage one direction only.

1 G. 2.8-2.9 PYROPHYLLITE (Pencil Stone},

2 Struct. — Foliated, granular, fibrous, radial, compact; indistinct orthorhombic crystals rare. Cleavage perfect, one direction (001) ; fracture uneven, splintery; thin flakes flexible, not elastic; feel greasy.

Color white, apple-green, gray, yellow. Streak white. Luster pearly to dull. Translucent to opaque. (See p. 256.)

In schistose rocks with cyanite, topaz, graphite, lazulite.

1 G."2.5-2.8 TALC (Steatite, Soapslone, Potstone},

2% Struct. — Foliated, granular; fibrous (agolite}; compact (soft, French chalk; waxy, rensselaerite} ; indistinct tabular monoclinic crystals rare. Cleavage perfect, one direction (001); thin flakes flexible, not elastic; sectile; fracture uneven; greasy feel. Hardness sometime 3-4.

58 Determinative Mineralogy [Sec. 9

H.

Color apple-green, gray, white. Streak white. Luster pearly, greasy. Transparent to opaque. (See pp. 236, 246, 256.)

In crystalline schists; with serpentine, dolomite, magnesite, chlorite, actinolite.

G. 2.6-2.7 VIVIANITE (Blue Iron Earth}, P2O5 28.3%. 2 Struct. — Radial fibrous, earthy; prismatic and tabular monoclinic crystals. Cleavage distinct, one direction (010); sectile; thin flakes flexible; fracture splintery, earthy.

Color blue, green, greenish black; colorless when fresh. Turns blue on exposure to light or grinding in a mortar. Streak white, greenish blue. Luster pearly on cleavage; vitreous, dull. Transparent to opaque. (See p. 218.) In clay, marl, peat; in cavities of fossils; with limonite; in veins with pyrrhotite, pyrite, gold.

G. 2'.3-2.4 GYPSUM (Selenite, Alabaster, Satin Spar), CaSO4-2H2O. 2 Struct. — Granular, foliated, fibrous; earthy (gypsite); diamond-shaped monoclinic crystals with beveled edges (Figs. 38, 39). Cleavage perfect, one direction (010), two others less conspicuous (111) (100) at 90°, 66°, and 114°; brittle, thin flakes flexible; fracture conchoidal, splintery.

Color white, colorless, gray, yellow, red. Streak white. Luster vitreous; pearly on (010); silky. Transparent to opaque. (See pp. 224, 226.)

Beds and masses with limestone, shale, clay, rock salt; near volcanic vents; with anhydrite, celestlte, sulphur, calcite, aragonite.

2 G. 1.7 BORAX (Tinkal), Na2B4O7-10H2O; B2O3 36.6%.

2% Struct. — Compact, earthy, incrusting; short columnar monoclinic crystals. Cleavage distinct, one direction (100); brittle; fracture conchoidal.

Color white, colorless, grayish, bluish, greenish. Streak white. Luster vitreous, greasy. Translucent to opaque. Sweetish alkaline taste. (See pp. 226, 228.)

In mud of alkaline lakes and marshes with halite, gypsum, colemanite.

2 G. 2.7-3.0 MUSCOVITE (Common or White Mica, Potash Mica, Isinglass)

3 often a little Na, Ca, Mg, Fe, and F. Struct. — Foliated, flaky; fine scaly to fibrous (seticite, damourite)', dense

(pinite); rarely distinct monoclinic (pseudohexagonal) crystals. Cleavage perfect, one direction (001); thin flakes tough, very elastic.

Color white, gray, yellowish, greenish, brownish. Streak white. Luster vitreous, pearly. Transparent to translucent. (See p. 236.)

In pegmatite, granite, gneiss, schists, contacts; with feldspars, quartz, tourmaline, beryl, garnet.

2 G. 2.8-3.1 BIOTITE (Black Mica, Ferromagnesian Mica),

3 a little F; often Ti.

Struct. — Plates, scales; pseudohexagonal monoclinic crystals rare. Cleavage conspicuous, one direction (001); thin flakes tough, very elastic, becoming more brittle with alteration.

Sec. 9] Physical Tables 59

H.

Color black, brownish black, greenish black, dark green. Streak white. Luster pearly, submetallic. Transparent to opaque. (See pp. 204, 220, 236.)

Common in granite, syenite, gneiss, mica schist; less common in basic igneous rocks and contacts.

2 G. 2.8-2.9 PHLOGOPITE (Amber Mica, Bronze Mica, Magnesia Mica),

3 some F and Fe.

Struct. — Plates, scales; prismatic or tabular monoclinic crystals with hexagonal or orthorhombic outline, commonly rough. Cleavage conspicuous, one direction (001); thin flakes tough, very elastic.

Color yellowish brown, brownish red, gray to green; rarely colorless. Streak white. Luster pearly, submetallic. Translucent to transparent. (See pp. 204, 236.)

Contacts in crystalline limestone; in serpentine; with pyroxene, amphibole, serpentine, graphite, apatite, corundum.

2 G. 2.8-2.9 Paragonite (Soda Mica),

3 Fine scaly masses, compact; strong pearly luster. Otherwise like muscovite above. In schists with cyanite, staurolite, tourmaline, garnet, actinolite. (See p. 236.)

3 G. 2.5-2.8 TALC (Steatite, Soapstone, Potstone),

4 Struct. — Foliated, granular; fibrous (agolite); compact (soft, French chalk; waxy, rensselaerite) ; indistinct tabular monoclinic crystals rare. Cleavage perfect, one direction (001); thin flakes flexible, not elastic; sectile; fracture uneven; greasy feel. Hardness commonly 1-2 1.

Color apple-green, gray, white. Streak white. Luster pearly, greasy. Transparent to opaque. (See pp. 236, 246, 256.)

In crystalline schists; with serpentine, dolomite, magnesite, chlorite, actinolite.

3J- G. 3.0-3.1 MARGARITE (Brittle Mica), H2CaAl4Si2Oi2; some Fe, Na, K. 4£ Struct. — Micaceous, scaly, granular; six-sided scales, plates (monoclinic). Cleavage perfect, one direction (001); flakes rather brittle, not elastic.

Color pink, grayish, white, yellowish. Streak white. Luster pearly on cleavage; vitreous. Translucent. (See pp. 236, 256.)

Coating or associated with corundum; also chlorite, spinel, emery, diaspore.

5 G. 3.3-3.5 HYPERSTHENE (a pyroxene), sometimes Al.

6 Struct. — Foliated, cleavable, granular; orthorhombic crystals rare. Cleavage perfect, one direction (010), less distinct in two directions (110), at 46°, 88°, 92°, 134°; brittle; fracture uneven.

Color grayish, greenish, and brownish black to bronze. Streak brownish gray, grayish white. Luster metalloidal, bronzy, pearly. Opaque to translucent. (See pp. 222, 258.)

In basic igneous rocks with plagioclase feldspars, olivine, amphibole, pyroxene, magnetite, titanite; seldom with quartz.

5£ PYROXENE, DIOPSIDE. (Sec p. 62.)

60 Determinative Mineralogy [Sbc. 9

H.

6 G. 3.2-3.4 ZOISITE, oftensomeFe. Struct. — Columnar, bladed, fibrous, compact; prismatic orthorhombic crystals striated lengthwise, without terminations. Cleavage conspicuous, one direction lengthwise (010) ; brittle; fracture uneven.

Color gray, yellowish brown, greenish; also red (thulite). Streak white. Luster vitreous; pearly on cleavage. Transparent to opaque. (See p. 246.) In crystalline schists with hornblende, vesuvianite, cyanite, epidote, garnet, feldspars, quartz.

6 G. 3.2-3.5 EPIDOTE (Pistacite),

7 Struct. — Long monoclinic crystals striated lengthwise, commonly terminated by two sloping faces; columnar, divergent acicular, granular. Cleavage distinct, one direction lengthwise (001); brittle; fracture uneven.

Color yellowish green to brown and black, gray, yellow, red. Streak white to grayish. Luster vitreous. Transparent to opaque. (See pp. 222,

In gneiss, schist, crystalline limestone, greenstone, with garnet, magnetite, chlorite, native copper, zeolites.

6 G. 3.3-3.5 DIASPORE, A1O-OH; Al 45%; sometimes Fe.

7 Struct. — Scaly, bladed, fibrous; columnar and tabular orthorhombic crystals rare. Cleavage distinct, one direction (010); brittle; fracture conchoidal.

Color white, grayish, greenish, hair-brown, yellow, colorless. Streak white. Luster vitreous; pearly on cleavage. Transparent to opaque. (See p. 260.)

With corundum, emery, dolomite, margarite, chlorite, magnetite.

6 G. 3.3-3.4 AXINITE, sometimes Mn, Fe, Mg.

7 Struct. — Tabular wedge-shaped triclinic crystals (Fig. 45); lamellar, granular. Cleavage distinct, one direction (010) ; brittle; fracture conchoidal.

Color clove-brown, yellow, greenish, grayish blue, gray. Streak white. Luster vitreous. Transparent to translucent. (See p. 242.) In veins with quartz, feldspars, hornblende, chlorite.

6 G. 3.5-3.6 Chloritoid (Ottrdtie), H2FeAl2SiO7; some Mg, sometimes Mn.

7 Struct. — Foliated, scaly, rosette groups; rarely tabular triclinic crystals, hexagonal in outline. Cleavage perfect, one direction (001); thin flakes brittle. (Ottrdite, oblong scales).

Color dark gray, greenish gray, greenish black. Streak white, grayish, pale green. Luster pearly, vitreous. Translucent to opaque. (See p. 222, 258, 260.)

In hornfels, slate, schist; with chlorite, hornblende, garnet, corundum.

7 G. 2.6-2.7 CORDIERITE (Mite, Dichroite, Water Sapphire),

Struct. — Short six- or twelve-sided orthorhombic (pseudohexagonal) crystals; granular, compact, disseminated. Cleavage one direction lengthwise (010); parting sometimes conspicuous crosswise (001); brittle; fracture uneven, conchoidal.

Secs. 9, 10] Physical Tables 61

H.

Color light to dark smoky blue, gray, violet, yellow. Resembles blue quartz; often altering to dull green chlorite; transparent varieties show marked differences in color in different directions. Streak white. Luster vitreous, dull. Transparent to translucent. (See p. 244, 260.)

In schists, gneiss, sometimes in granite; with quartz, feldspars, hornblende, tourmaline, andalusite, sillimanite, garnet.

Section 10

Streak chalk- white, colorless, or pale colored; mineral dark gray to black; distinct cleavage two directions.

3£ G. 3.7 STRONTIANITE (Strontian Spar) , SrCO3; SrO70.1%; some-

4 times Ca.

Struct. — Chisel- or spear-shaped orthorhombic crystals, pseudohexagonal prisms; columnar, acicular, fibrous, divergent; granular, compact; Cleavage distinct, two directions at 63° and 117° (110); brittle; fracture uneven.

Color white, colorless, grayish, greenish, yellowish. Streak white. Luster vitreous, greasy. Transparent to translucent. (See p. 246.)

In ore deposits with galena, barite, calcite, celestite, fluorite, pyrite; veins in limestone, chalk, marl.

4 G. 3.5-3.7 CYANITE (Kyanite, Disthene), Al2SiO5, or

5 Struct. — Long tabular or bladed tri clinic crystals without terminations; may be curved or radiating. Cleavage pronounced, two directions lengthwise at 74° and 106° (100) (010); transverse parting (001) common; brittle; fracture splintery.

Color blue, white, gray, green, nearly black; often streaked. Streak white. Luster vitreous. Transparent to translucent. (See p. 256, 260.)

Hardness lengthwise 4-5, crosswise 6-7. In gneiss and mica schist with staurolite, garnet, corundum.

5 G. 3.4-3.6 TITANITE (Spheric), CaSiTi05; commonly a little Fe.

Struct. — Tabular or wedge-shaped monoclinic crystals; lamellar, compact. Cleavage distinct, two directions at 66|° and 113|° (110); parting often distinct four directions at 54° and 126° (221); brittle; fracture conchoidal.

Color brown to black, yellow, gray, green; rarely rose-red. Streak white. Luster vitreous, resinous, adamantine. Transparent to opaque. (See p. 234, 246.)

Accessory in many igneous rocks; in gneiss, chlorite schist, crystalline limestone; with chlorite, iron oxides, pyroxene, amphibole, zircon, apatite, feldspars, quartz, rutile.

5 G. 2.9-3.4 HORNBLENDE (an amphibole), Silicate of Ca, Mg, Fe, Al, etc.

6 Struct. — Granular, columnar, fibrous, radiated; long prismatic monoclinic crystals, often rhombohedron-like terminations; prism angle 124°; some prisms short, six-sided. Cleavage perfect, two directions lengthwise at 56° and 124° (110); brittle; fracture uneven, splintery.

62 Determinative Mineralogy [Sec. 10'

H.

Color green, black, brown, gray. Streak brown, green, yellow, gray, white. Luster submetallic, vitreous, pearly, silky. Translucent to opaque. (See pp. 222, 238.)

Common in igneous and metamorphic rocks with feldspars, pyroxenes, chlorite, quartz, calcite.

5 G. 2.9-3.1 TREMOLITE (Grammatite, an amphibole),

6 Struct. — Bladed, columnar, fibrous, compact; bladed monoclinic crystals without terminations; prism angle 124°. Cleavage conspicuous, two directions lengthwise, 56° and 124° (110); brittle; small fibers flexible; fracture uneven. Nephrite or jade, in part tremolite, is dense, compact, tough.'

Color white to dark gray, yellowish, colorless. Streak white. Luster vitreous, silky, pearly. Transparent to opaque. (See p. 238.)

In limestone, dolomite, schist; common at contracts; with pyroxene, garnet, vesuvianite, epidote.

5 G. 3.0-3.2 Anthophyllite (an amphibole), sometimes Al

6 (Gedrite).

Struct. — Lamellar, columnar, fibrous; prismatic orthorhombic crystals rare. Cleavage two directions lengthwise at 54|° and 125|° (110); brittle; fracture splintery; fine fibers flexible (asbestos}.

Color gray, clove-brown, greenish to emerald. Streak white. Luster vitreous, pearly, silky, sometimes metalloidal. Translucent to opaque. (See pp. 222, 238, 258.)

In schists with talc, hornblende, chlorite, mica.

5 G. 3.2-3.6 PYROXENE, ranging from Diopside,

6 to Hedenbergite, often some Al, Mn, and Na.

AUGITE (a pyroxene), like common pyroxene above, with A12O3 up to 15% or 20%; sometimes Na and K.

Struct. — Granular, columnar, rarely fibrous; lamellar (diallage)', thick monoclinic prisms four or eight-sided (Figs. 40, 41). Cleavage two directions lengthwise at 87° and 93° (110), sometimes distinct; often prominent parting crosswise (001); diallage has fine lamellar parting one direction lengthwise (100); brittle; fracture uneven.

Color bright to dark green, grayish green, black, brown. Streak greenish, brownish, grayish to white. Luster vitreous, submetallic, dull. Transparent to opaque. (See pp. 220, 222, 240.)

Common in basic igneous rocks; in crystalline limestones with garnet, chlorite, amphibole, wollastonite, magnetite, pj'rite.

5 G. 3.2-3.6 DIOPSIDE (Malacolite, a pyroxene), some Fe.

6 Struct. — Prismatic monoclinic (pseudotetragonal) crystals, stout, terminated (Figs. 40, 41); lamellar, granular, compact. Cleavage two directions lengthwise at 87° and 93° (110) sometimes distinct; often conspicuous transverse parting (001); brittle; fracture uneven.

Sec. 10] Physical Tables 63

H.

Color white, colorless, grayish, green to black. Streak white, grayish, greenish. Luster vitreous, dull. Transparent to opaque. (See p. 240.)

In basic igneous rocks; in crystalline limestones with wernerite, vesuvianite, garnet.

5£ G. 4.0-4.1 Tephroile, Mn2SiO4; commonly also Mg and a little Fe. 6 Struct. — Cleavable, granular, compact; orthorhombic crystals rare. Cleavage distinct, two directions at 90°; brittle; fracture conchoidal, uneven. Color ash-gray, flesh-red, brown. Streak pale gray. Luster vitreous, greasy. Translucent to opaque. (See p. 230.)

In crystalline limestone with zincite, willemite, franklinite, rhodonite (Franklin, N. J.); with other manganese minerals.

6 G. 2.5-2.6— ORTHOCLASE (Potash Feldspar), KAlSi3O8; K20 16.9%; 6£ often Na.

Struct. — Cleavable, granular, disseminated grains; prismatic and tabular monoclinic crystals and twins (Figs. 42 to 44). Cleavage distinct, two directions at 90° (010) (001); brittle; fracture conchoidal, uneven.

Color white, red, gray, green, colorless. IStreak white. Luster vitreous; often pearly on cleavage. Transparent to opaque. (See p. 238.)

In many igneous and metamorphic rocks; in veins and contacts; with quartz, other feldspars, mica, hornblende, pyroxene; in pegmatite with beryl, topaz, tourmaline. For varieties see p. 37.

6 G. 2.6-2.8 PLAGIOCLASE (Soda-lime and Lime-soda Feldspars), ranging from NaAlSisOg (ab) to CaAl2Si2O8 (an) ; generally some K.

Comp. Sp. Gr. Comp. Sp. Gr.

Albite, ab-abeam , 2.62-2.64 Labradorite, abia-abn 2.70-2.72 Oligoclase, abeani-absani, 2.65-2.67 Bytownite, abian3-abiane, 2.73-2.75 Andesine, ab3ani-abiani, 2.68-2.69 Anorthite, abian6-an, 2.75-2.76 Struct. — Lamellar, granular, disseminated; small tri clinic crystals (Fig. 46). Cleavage distinct, two directions at 86°-86° and 940-93£0 (001) (010) ; often striations on one cleavage; cleavage often curved; brittle; fracture uneven.

Color white, colorless, gray, green, bluish, reddish; sometimes play of colors — blue, green, yellow, red. Streak white. Luster vitreous; often pearly on cleavage. Transparent to opaque, sometimes opalescent (moonstone), or with bright reddish or yellowish reflections from included scales (aveniurine feldspar, or sunstone). (See p. 238.)

In igneous rocks, gneisses, schists; with otjier feldspars, quartz, mica, chlorite, zeolites; sometimes in veins.

6 G. 3.5-3.6 Aegirite (Aegirine, Acmife, a pyroxene), Struct. — Long prismatic monoclinic crystals with terminations blunt (aegirite) or sharp (acmile)', acicular, fibrous. Cleavage distinct, two directions at 87° and 93° (110); brittle; fracture uneven.

Color greenish black to reddish and brownish black; acmite often green interior, brown exterior. Streak pale yellowish gray. Luster vitreous, resinous. Translucent to opaque. (See pp. 222, 240.)

In igneous rocks rich in soda and iron — aegirite granite, nephelite syenite, phonolite, pegmatite.

64 Determinative Mineralogy [Secs. 10, 11

H.

6 G. 3.0-3.1 Glaucophane (an amphibole), Struct. — Columnar, fibrous, granular; prismatic monoclinic crystals, commonly indistinct. Cleavage distinct, two directions lengthwise at 58° and 122° (110); brittle, small fibers flexible; fracture uneven, conchoidal.

Color lavender blue, azure blue, bluish to grayish black. Streak white. Luster vitreous, pearly, silky. Translucent to opaque. (See p. 238.)

In schists and gneisses with mica, garnet, epidote, zoisite, amphiboles, pyroxenes.

6 G. 3.5-3.7 CYANITE (Kyanite, Disthene), Al2Si05, or

7 Struct. — Long tabular or bladed tri clinic crystals without termination; may be curved or radiating. Cleavage pronounced, two directions lengthwise at 74° and 106° (100) (010); transverse parting (001) common; brittle; fracture splintery.

Color blue, white, gray, green, nearly black; often streaked. Streak white. Luster vitreous. Transparent to translucent. (See pp. 256, 260.)

Hardness lengthwise 4-5, crosswise 6-7. In gneiss and mica schist with staurolite, garnet, corundunj.

6 G. 3.1-3.2 SPODUMENE (a pyroxene), Li2O 8.4%; some Na.

7 Struct. — Cleavable, columnar, compact; rough prismatic or flattened monoclinic crystals, striated lengthwise. Cleavage conspicuous, two directions lengthwise at 87° and 93° (110); parting sometimes prominent one direction (100), bisecting larger cleavage angle; brittle; fracture uneven, splintery.

Color white, gray, yellowish; emerald-green (hiddenite); pink to purple (kunzite). Streak white. Luster vitreous, pearly. Transparent to opaque. (See pp. 240, 242.)

In pegmatites with tourmaline, lepidolite, beryl, amblygonite, cassiterite.

RUTILE. (See p. 72.)

G. 3.1-3.2 ANDALUSITE (Chiastolite, Macle), Al2SiO5, or Struct. — Columnar, granular, disseminated; rough orthorhombic prisms, nearly square. Cleavage distinct, two directions at 89° and 91° (110); brittle; fracture uneven.

Color white, pink, reddish brown, olive-green; sometimes black and white cross or checkered pattern on cross-fracture (chiastolite, or made). Streak white. Luster vitreous, dull. Translucent to opaque. (See p. 260.)

In slate, schists, and gneiss; with sillimanite, garnet, biotite, tourmaline, cordierite.

Section 11

Streak chalk- white, colorless, or pale colored; mineral dark gray to black; distinct cleavage three or more directions.

li G. 2.3-2.4 GYPSUM (Selenite, Alabaster, Satin Spar), CaSO4-2H2O.

2 Struct. — Granular, foliated, fibrous; earthy (gypsite); diamond-shaped monoclinic crystals with beveled edges (Figs. 38, 39). Cleavage perfect, one direction (010), two others less conspicuous (111) (100) at 90°, 66°, and 114°; brittle, thin flakes flexible; fracture conchoidal, splintery.

Sec. 11] Physical Tables 65

H.

Color white, colorless, gray, yellow, red. Streak white. Luster vitreous; pearly on (010); silky. Transparent to opaque. (See pp. 224, 226.)

Beds and masses with limestone, shale, clay, rock salt; near volcanic vents; with anhydrite, celestite, sulphur, calcite, aragonite.

2 G. 2.1-2.6 HALITE (Common Salt, Rock Salt), NaCl; Na 60.6%; often 2-J- Ca and Mg.

Struct. — Granular, cleavable, compact; isometric crystals (cubes, Fig. 5). Cleavage distinct, three directions at 90° (100); brittle; fracture conchoidal. Color white, colorless, grayish, reddish, bluish. Streak white. Luster vitreous. Transparent to translucent. Taste salty. (See p. 224.)

Beds in sedimentary strata with gypsum, anhydrite, sylvite, calcite, clay, sand; in dry lakes; in brines.

2 G. 1.9-2.0 SYLVITE, KC1; K 52.4%; sometimes Na.

2% Struct. — Granular, compact; isometric crystals (cubes, Fig. 5). Cleavage distinct, three directions at 90° (100); brittle; fracture conchoidal.

Color white, colorless, grayish, bluish, reddish. Streak white. Luster vitreous. Transparent to translucent. Taste salty, bitter. Becomes damp in moist air. (See p. 224.)

In salt deposits; with halite, kainite, carnallite.

3 G. 2.7 CALCITE (Calc Spar), CaCO3; often Mg, Fe, Mn, sometimes Pb.

Struct. — Hexagonal-rhombohedral crystals, prismatic, scalenohedral, rhombohedral, tabular, or acicular in habit (Figs. 52 to 57); rarely twins; cleavable, granular, stalactitic, oolitic, earthy. Cleavage perfect, three directions at 75° and 105° (lOll); brittle; fracture conchoidal, seldom observed.

Color white, colorless, pale shades of gray, yellow, red, green, blue, violet; brown to black when impure. Streak white. Luster vitreous, dull. Transparent to opaque. (See p. 246.)

Chief constituent of limestone, marble, chalk, calcareous marl; in veins with metallic ores, quartz, pyrite, zeolites. For varieties, see p. 40.

3 G. 6.1-6.4 ANGLESITE (Lead Vitriol), PbSO4; Pb 68.3%.

Struct. — Orthorhombic crystals; granular, compact. Cleavage three directions at 76°, 90°, and 104° (001) (110), not conspicuous; brittle; fracture conchoidal.

Color white, colorless, gray, brown, green. Streak white. Luster adamantine, vitreous. Transparent to translucent. (See p. 214.)

In oxidized parts of ore deposits with lead, zinc, and iron minerals.

3 G. 2.9-3.0 ANHYDRITE (Anhydrous Gypsum), CaSO4 3£ Struct. — Granular, compact, fibrous, cleavable; rarely orthorhombic crystals. Cleavage distinct, three directions at 90° (001) (100) (010); brittle; fracture conchoidal.

Color white, grayish, bluish, reddish to brick-red. Streak white to grayish. Luster vitreous; pearly on (001). Translucent to opaque. (See p. 226.) In limestones, shales, salt deposits; with halite, gypsum, calcite.

66 DETERMINflVE MINERALOGY [SEC. 11

H.

G. 2.8-2.9 DOLOMITE, sometimes Fe and Mn; much Fe, 4 Ankerite.

Struct. — Granular, cleavable, compact; hexagonal-rhombohedral crystals, faces often curved (pearl spar). Cleavage perfect, three directions at 74° and 106° (lOll); brittle; fracture conchoidal, uneven.

Color white, colorless, gray, red, green, brown, black. Streak white. Luster vitreous, pearly. Transparent to opaque. (See p. 246.)

Extensive strata as dolomitic limestone and marble; gangue with ores of lead, zinc, etc.; with serpentine, talc, gypsum, and ordinary limestones.

3 1 G. 3.8-3.9 SIDERITE (Spathic Iron, Chalybite, Clay Ironstone, Black 4 Band Ore), FeCO3; Fe 48.3%.

Struct. — Granular, cleavable, compact; hexagonal rhombohedral crystals, curved and saddle-shaped common. Cleavage perfect, three directions at 73° and 107° (lOll); brittle; fracture uneven.

Color gray, yellow, brown, black, sometimes white. Streak white, pale yellow. Luster vitreous, pearly, dull. Translucent to opaque. (See pp. 218, 248.)

In veins with silver minerals, pyrite and other sulphides, cryolite; beds and concretions in limestone, shale, and coal.

3£ G. 2.9-3.0 ARAGONITE (Flos Ferri), CaCO3; sometimes Sr and Pb. 4 Struct. — Chisel- or spear-shaped orthorhombic crystals, pseudohexagonal prisms; acicular, columnar, stalactitic, coral-like. Cleavage three directions at 64°, 90°, and 116° (110) (010); brittle; fracture conchoidal.

Color white, gray, yellow, pale green, violet. Streak white. Luster vitreous, resinous. Transparent to translucent. (See p. 246.)

In gypsum beds, basalt, serpentine, beds of limonite and siderite; with celestite, sulphur, metallic sulphides, zeolites; constitutes some shells (pearly layers of many) and coral.

G. 3.9-4.1 SPHALERITE (Blende, Zinc Blende, Jack, Black Jack, Rosin 4 Jack), ZnS; Zn 67%; may be replaced by Fe up to 18%.

Struct. — Cleavable masses, granular, compact, botryoidal; rounded isometric-tetrahedral crystals. Cleavage pronounced, six directions at 60°, 90°, and 120° (110); brittle; fracture conchoidal.

Color yellow, brown, red, green, black; rarely white or pale gray (cleiophane). Streak white, light to dark brown. Luster resinous, adamantine, submetallic. Transparent to opaque. (See pp. 200, 228, 250.)

Ore deposits and veins with galena, pyrite, chalcopyrite, fluorite, barite; also in limestones.

4 G. 3.5-3.7 CYANITE (Kyanite, Disthene), Al2SiO5, or

5 Struct. — Long tabular or bladed triclinic crystals without terminations; may be curved or radiating. Cleavage pronounced, two directions lengthwise at 74° and 106° (100) (010); transverse parting (001) common; brittlefracture splintery.

Sec. 11] Physical Tables 67

H.

Color blue, white, gray, green, nearly black; often streaked. Streak white. Luster vitreous. Transparent to translucent. (See pp. 256, 260.)

Hardness lengthwise 4-5, crosswise 6-7. In gneiss and mica schist with staurolite, garnet, corundum.

5 G. 3.2-3.6 PYROXENE, ranging from Dioptide,

6 to Hedenbergite, often some Al, Mn, and Na.

AUGITE (a pyroxene), like common pyroxene above, with A12O3 up to 15% or 20%; sometimes Na and K.

Struct. — Granular, columnar, rarely fibrous; lamellar (diallage}; thick monoclinic prisms four- or eight-sided (Figs. 40, 41). Cleavage two directions lengthwise at 87° and 93° (110), sometimes distinct; often prominent parting crosswise (001); diallage has fine lamellar parting one direction lengthwise (100); brittle; fracture uneven.

Color bright to dark green, grayish green, black, brown. Streak greenish, brownish, grayish to white. Luster vitreous, submetallic, dull. Transparent to opaque. (See pp. 220, 222, 240.)

Common in basic igneous rocks; in crystalline limestones with garnet, chlorite, amphibole, wollastonite, magnetite, pyrite.

5 G. 3.2-3.6 DIOPSIDE (Malacolite, a pyroxene), some Fe.

6 Struct. — Prismatic monoclinic (pseudotetragonal) crystals, stout, terminated (Figs. 40, 41); lamellar, granular, compact. Cleavage two directions lengthwise at 87° and 93° (110) sometimes distinct; often conspicuous transverse parting (001); brittle; fracture uneven.

Color white, colorless, grayish, green to black. Streak white, grayish, greenish. Luster vitreous, dull. Transparent to opaque. (See p. 240.)

In basic igneous rocks; in crystalline limestones with wernerite, vesuvianite, garnet.

5 G. 2.5-2.6 NEPHELITE (Nepheline, Elaeolite, a feldspathoid), NaAlSiO4;

6 alsoK (upto7%K2O).

Struct. — Compact, disseminated grains; small hexagonal crystals rare; Cleavage distinct, three directions at 60° and 120° (lOll); brittle; fracture conchoidal, uneven.

Color reddish, brownish, greenish, gray, white, colorless. Streak white. Luster greasy, vitreous. Transparent to opaque. (See p. 232.)

In lavas and granular igneous rocks with feldspars, sodalite, cancrinite, biotite, zircon, corundum; not with quartz.

5 G. 3.3-3.5 HYPERSTHENE (a pyroxene), sometimes Al.

6 Struct. — Foliated, cleavable, granular; orthorhombic crystals rare. Cleavage perfect, one direction (010), less distinct in two directions (110), at 46°, 88°, 92°, 134°; brittle; fracture uneven.

Color grayish, greenish, and brownish black to bronze. Streak brownish gray, grayish white. Luster metalloidal, bronzy, pearly. Opaque to translucent. (See pp. 222, 258.)

In basic igneous rocks with plagioclase feldspars, olivine, amphibole. pyroxene, magnetite, titanite; seldom with quartz.

68 Determinative Mineralogy [Sec. 11

H.

5 G. 2.4-2.5 CANCRINITE (a feldspathoid),

6 Struct. — Compact, lamellar, columnar, disseminated; prismatic hexagonal crystals rare. Cleavage distinct, three directions at 60° and 120° (lOlO); brittle; fracture uneven.

Color white, gray, yellow, green, blue, reddish. Streak white. Luster vitreous, greasy, pearly. Transparent to translucent. (See p. 230.)

In granular igneous rocks with nephelite, sodalite, biotite, feldspars, titanite; not with quartz.

G. 3.8-3.9 Octahedrite (Anatase), TiO2; Ti 60%.

6 Struct. — Tetragonal crystals, pyramidal, tabular, rarely prismatic. Cleavage distinct, five directions at 82°, 111°, and 136|° (111) (001); brittle; fracture uneven.

Color brown, dark blue, black. Streak white, pale gray. Luster adamantine, metallic. Translucent to opaque. (See pp. 210, 262.)

Minute crystals in granular igneous rocks; in gneiss, schists, quartzite, limestone; with brookite, rutile, ilmenite, biotite, adularia, titanite, gold.

G. 4.0 Perovskite (Perofskite), CaTiO3; some Fe.

6 Streak. — Isometric (or pseudoisometric) crystals, commonly cubes (Fig. 5), often highly modified and striated; reniform aggregates, rounded grains; Cleavage distinct, three directions at 90° (100); brittle; fracture uneven.

Color pale yellow to orange-yellow, reddish brown, grayish black. Streak white, grayish. Luster adamantine, submetallic. Transparent to opaque. (See pp. 210, 258.)

In schists, crystalline limestone, serpentine, basic igneous rocks; with chlorite, magnetite, garnet, vesuvianite, rutile, ilmenite, corundum.

6 G. 3.5-3.7 CYANITE (Kyanite, Disthene), Al2SiO6, or

7 Struct. — Long tabular or bladed triclinic crystals without termination; may be curved or radiating. Cleavage pronounced, two directions lengthwise at 74° and 106° (100) (010); transverse parting (001) common; brittle; fracture splintery.

Color blue, white, gray, green, nearly black; often streaked. Streak white. Luster vitreous. Transparent to translucent. (See pp. 256, 260.)

Hardness lengthwise 4-5, crosswise 6-7. In gneiss and mica schist with staurolite, garnet, corundum.

G. 3.4-4.3 GARNET, R"=Ca, Mg, Fe, Mn; R'"=A1, 7£ Fe, Cr, sometimes Ti.

Struct. — Isometric crystals (dodecahedrons, trapezohedrons, Figs. 3, 7, 8); granular, lamellar, compact, disseminated, sand. Cleavage none; parting sometimes distinct, six directions at 60°, 90°, and 120° (110); brittle; fracture conchoidal, uneven.

Color red, brown, black, green, purple, etc. (See varieties, p. 101.) Streak white. Luster vitreous. Transparent to opaque. (See p. 244.) For varieties and occurrence, see p. 101.

Secs. 11, 12] Physical Tables 69

H.

9 G. 3.9-4.1 CORUNDUM (Adamantine Spar), A1203.

Struct. — Rough hexagonal-rhombohedral crystals, prismatic, pyramidal, tabular, tapering (barrel-shaped), often striated; lamellar, granular, compact. Cleavage none; often conspicuous parting three directions at 86° and 94° (lOll); sometimes transverse parting (0001); brittle, tough when compact; fracture uneven, conchoidal.

Color white, gray, brown, to black; deep red (ruby)', blue (sapphire)', black from admixture of magnetite, hematite, or spinel (emery). Streak white. Luster vitreous, adamantine. Transparent to opaque. (See p. 260.)

In peridotite, gneiss, schist, syenite, crystalline limestone; with olivine, chlorite, serpentine, magnetite, spinel, vermiculite; cyanite, diaspore, muscovite.

10 G.3.5 DIAMOND (Carbon), C.

Struct. — Isometric crystals (octahedron, hexoctahedron, Figs. 1, 4) usually with curved surfaces; rounded and irregular grains, pebbles, often with radial structure. Cleavage distinct, four directions at 70|° and 109° (111) ; brittle; fracture conchoidal.

Color white, colorless, pale shades of yellow, red, orange, green, blue, brown; occasionally black. Streak white. Luster adamantine, greasy. Transparent to opaque. Bort, rough rounded masses with radial or confused crystalline structure, without distinct cleavage; grayish to black; sp. g. 3.5. Carbonado, or black diamond, granular to compact, without cleavage; sp. g. 3.1-3.3. (See p. 264.)

In peridotite or serpentine; in sands, gravels, quartzite; with pyrope, magnetite, chromite, zircon, gold.

Section 12

Streak chalk-white, colorless, or pale colored; mineral dark gray to black; no distinct cleavage.

1 G. 5.5-5.6 CERARGYRITE (Horn Silver), AgCl; Ag 75.3%; sometimes Hg. 1£ Struct. — Wax-like crusts, stalactitic, dendritic; isometric (cubic) crystals rare. Cleavage none; highly sectile; fracture conchoidal.

Color pearly gray, greenish, colorless; turns violet, brown to black on exposure to light. Streak white, grayish, shiny. Luster waxy, greasy, resinous. Transparent to translucent. (See p. 216.)

In veins with other silver minerals, calcite, barite, limonite.

1 G. 2.2-2.4 GLAUCONITE (Greensand, Green Earth), approx. -H2O;

2 K2O 6.9%; some Al and Mg.

Struct. — Granular, earthy, disseminated; amorphous. Cleavage none; brittle; fracture earthy, uneven.

Color yellowish green, grayish green, blackish green. Streak light green, greenish white. Luster vitreous, dull. Opaque. (See p. 220.)

Abundant in greensand beds (so-called marls); disseminated in sands, clays, sandstones, limestones.

70 Determinative Mineralogy [Sec. 12

H.

1 G. 0.9-1.0 OZOCERITE (Mineral Wax, Native Paraffin), CnH2n+2.

2 Struct. — Amorphous, compact, fibrous, lamellar; piastre; may be sticky. Color black, brownish black, brownish yellow, leek-green. Streak yellow-

ish brown, pale yellow. Luster waxy, greasy, submetallic. Translucent, sometimes greenish opalescence. (See p. 212.)

Like wax; greasy feel. Burns with bright smoky flame and odor of paraffin. In veins in sedimentary rocks.

1 G. 6.4-6.5 Calomel (Horn Quicksilver), HgzCfc; Hg 84.9%.

2 Struct. — Coatings; small tetragonal crystals, tabular, pyramidal. Cleavage indistinct, two directions (100) at 90°; sectile; fracture conchoidal.

Color white, gray, yellowish to brown. Streak white, gray, yellowish. Luster adamantine. Translucent to opaque. (See p. 212.) In veins with cinnabar and mercury.

2 G. 2.6-2.7 Pharmacolite (Arsenic Bloom), HCaAs04-2H20. 2% Struct. — Fibrous, acicular, incrusting, powdery; small prismatic monoclinic crystals rare. Cleavage distinct, one direction lengthwise (010); sectile; thin flakes flexible; fracture uneven.

Color white, grayish; may be tinged red by Co or green by Ni. Streak white. Luster vitreous, pearly. Translucent to opaque. (See p. 228.) With arsenopyrite and arsenical ores of cobalt and silver.

2 G. 5.2-5.3 Senarmontite, Sb2O3; Sb 83.3%.

Struct. — Isometric crystals (octahedrons, Fig. 1); granular, incrusting. Cleavage indistinct; brittle; fracture uneven.

Color white, colorless, grayish. Streak white. Luster greasy, pearly. Transparent to translucent. (See p. 212.) With stibnite and other antimony minerals.

3 G. 6.4-6.6 CERUSITE (White Lead Ore), PbCO3; Pb 77.5%.

3£ Struct. — Pseudohexagonal orthorhombic crystals, clusters, star-shaped groups; granular, fibrous, compact. Cleavage indistinct; brittle; fracture conchoidal.

Color white, gray, colorless; or yellow, brown, etc., from impurities. Streak white. Luster adamantine, greasy, silky. Transparent to translucent. (See p. 214.)

In oxidized parts of lead ores with lead, zinc, iron, and copper minerals.

3 G. 2.5-2.6 SERPENTINE, H4Mg3Si2O9; commonly Fe, sometimes Ni.

4 Struct. — Massive compact, fibrous (chrysotile, asbestos)', lamellar (marmolite)', columnar (picrolite) ; brittle; fibers flexible and tough; fracture conchoidal, splintery.

Color olive-green, blackish green, yellowish green, yellow; rarely white. Streak white. Luster greasy, waxy, silky. Translucent to opaque. (See pp. 232, 254.)

Common alteration product of olivine rocks (peridotites) ; in dolomitic limestone; with magnesite, talc, chromite, magnetite, corundum, platinum, diamond. Mixed with dolomite, calcite, or magnesite in a mottled or clouded green marble (vcrdantique, or ophicalciie) .

Sec. 12] Physical Tables 71

3 G. 4.3-4.4 WITHERITE, BaCO3; BaO 77.7', t.

4 Struct. — Compact, granular, radial fibrous, lamellar; pseudohexagonal orthorhombic crystals resembling quartz. Cleavage indistinct; brittle; fracture uneven.

Color white, grayish, yellowish. Streak white. Luster vitreous, greasy. Transparent to translucent. (See p. 226.) In veins with galena, barite, fluorite, calcite.

G. 6.5-7.1 PYROMORPHITE (Green Lead Ore), Pb 76.3%; 4 P205 15.7%.

Struct. — Small prismatic hexagonal crystals, often rounded, barrelshaped, sometimes hollow; incrusting, reniform, disseminated. Cleavage none; brittle; fracture conchoidal, uneven.

Color green, yellow, brown, white, gray. Streak pale yellow, greenish yellow, white. Luster resinous, greasy, adamantine. Translucent to opaque. (See p. 214.)

In oxidized parts of lead veins with galena, cerusite, mimetite, barite, limonite.

3f G. 3.1-3.3 SCORODITE, FeAsO4-2H2O.

4 Struct. — Pyramidal orthorhombic crystals, sometimes prismatic or tabular; botryoidal, fibrous, earthy, amorphous. Cleavage imperfect, two directions at 60° and 120° (120); brittle; fracture conchoidal, uneven.

Color pale green, bluish green, blackish green, blue, brown. Streak white, grayish, greenish. Luster . vitreous, greasy. Translucent. (See p. 218.)

With arsenopyrite, enargite, limonite, pyrite.

5 G. 2.1-2.3 SODALITE (a feldspathoid),

6 Struct. — Compact, disseminated grains, nodular; isometric crystals (dodecahedrons) rare. Cleavage indistinct, six directions at 60°, 90°, and 120° (110); brittle; fracture conchoidal, uneven.

Color blue, gray, white, red, green. Streak white. Luster vitreous, greasy. Transparent to translucent. (See p. 230.)

In igneous rocks with nephelite, leu cite, cancrinite; not with quartz.

G. 2.4-2.5 LEUCITE (Amphigene, a feldspathoid), K2O 21.5%. 6 Struct. — Isometric crystals (trapezohedrons, Fig. 3) ; rounded disseminated grains. Cleavage indistinct; brittle; fracture conchoidal.

Color white, gray, yellowish, reddish, colorless. Streak white. Luster vitreous, greasy. Translucent to opaque. (See p. 254.)

In lavas with sanidine, augite, nephelite, olivine; not with quartz.

5£ G. 3.0-4.2 ALLANITE (Orthite), also La, Nd,

6 Pr, Y.

Struct. — Compact, granular, bladed, disseminated; rough tabular monoclinic crystals rare. Cleavage indistinct; brittle; fracture conchoidal, uneven.

72 Determinative Mineralogy [Sec. 12

H.

Color brownish black, pitch black. May be coated with yellowish or brownish alteration product. Streak pale gray, greenish, brownish. Luster metallic, submetallic, pitchy, vitreous. Translucent to opaque. (See pp. 206, 220, 232.)

Minor accessory in the acid igneous rocks with magnetite, epidote, quartz, feldspars; also in limestones.

G. 3.9-4.1 Brookite (Arkansite),.TiOz; Ti 60%.

6 Struct. — Orthorhombic crystals, often tabular (pseudohexagonal), also prismatic, faces often striated. Cleavage indistinct; brittle; fracture uneven.

Color hair-brown, yellowish and reddish brown to iron-black. Streak white, grayish, yellowish, brownish. Luster adamantine, metallic. Opaque. (See pp. 210, 262.)

In igneous rocks, gneiss, crystalline limestone; in veins with quartz, feldspars, metallic sulphides; with rutile, octahedrite, titanite, adularia, nephelite; in gold placers.

G. 4.3-5.8 Fergusonite, some Ca, Fe, H20. 6 Struct. — Disseminated, compact; pyramidal tetragonal crystals rare. Cleavage none; brittle; fracture conchoidal, uneven.

Color brownish black, brown. Streak pale brown. Luster submetallic, vitreous; often dull outside. Translucent to opaque. (See pp. 210, 264.)

Brilliant luster of fresh fracture in striking contrast with dull surface. In granite and pegmatite with quartz, feldspars, zircon, allanite, gadolinite; in placer gravels.

5£ G. 2.1-2.2 OPAL, SiO2-nH2O ; H2O 2-16%; chiefly 3-9%. Struct. — Amorphous, botryoidal, reniform, stalactitic, earthy. Cleavage none; brittle; fracture conchoidal, conspicuous when compact.

Color white, yellow, red, brown, green, gray, blue, colorless; sometimes a rich play of colors (precious opal). Streak white. Luster vitreous, pearly, dull. Transparent to opaque. (See pp. 256, 260, 264.)

In cavities and veins in igneous and sedimentary rocks. For varieties see p. 54.

6 G. 2.8-3.0 Prehnite,

Struct. — Botryoidal, stalactitic, radial fibrous; rounded groups of tabular orthorhombic crystals; distinct crystals rare. Cleavage indistinct, one direction (001); brittle; fracture uneven.

Color light green, oil-green, gray, white; often fading on exposure. Streak white. Luster vitreous, waxy. Transparent to translucent. (See pp. 234, 244.)

With zeolites, datolite, apophyllite, pectolite, native copper, calcite, quartz, epidote, chlorite — in igneous rocks, chiefly basic.

6 G. 4.1-1.3 RUTILE (Nigrine), TiO2; Ti 61%; often Fe.

7 Struct. — Prismatic tetragonal crystals striated lengthwise; knee-shaped and rosette twins; acicular, compact, disseminated. Cleavage indistinct; sometimes distinct 2 directions at 45° (100) (110); brittle; fracture uneven.

Sec. 12] Physical Tables 73

H.

Color red, reddish brown, black (deep red when transparent). Streak white, gray, pale brown. Luster metallic, adamantine. Transparent to opaque. (See pp. 210, 262.)

In veins with quartz, feldspars, hematite, ilmenite; hair-like inclusions in quartz; in igneous contacts and metamorphic rocks.

6 G. 6.8-7.1 CASSITERITE (Tinstone), SnO2; Sn 78.6%; sometimes Fe

7 and Ta.

Struct. — Granular, disseminated, reniform with radiating fibrous structure (wood tin), sand and pebbles (stream tin); thick prismatic tetragonal crystals, knee-shaped twins common (Fig. 29). Cleavage indistinct; brittle; fracture uneven.

Color brown to black, rarely yellow, red, gray, white. Streak white, grayish, brownish. Luster adamantine, greasy, dull. Transparent to opaque. (See p. 262.)

In granite, gneiss, with wolframite, scheelite, molybdenite, tourmaline, fluorite, topaz, apatite, lepidolite; in pegmatites; in sands and gravels.

6 G. 4.0-4.5 Gadolinite, some Ce, La, Nd, Pr, Er, Sc, etc.

7 Struct. — Compact, disseminated, nodular; rough prismatic monoclinic crystals rare. Cleavage none; brittle; fracture conchoidal, splintery.

Color black, greenish black, brown; thin splinters grass-green to olivegreen. Streak greenish gray. Luster vitreous, greasy. Translucent to opaque. (See pp. 232, 252.)

In granite and pegmatite with quartz, mica, allanite, fergusonite, fluorite, molybdenite.

G. 3.4-4.3 GARNET, R" Ca, Mg, Fe, Mn, Ti; R'"=A1, Fe, Cr, Ti.

Struct. — Isometric crystals (dodecahedrons, trapezohedrons, Figs. 3, 7, 8); granular, lamellar, compact, disseminated, sand. Cleavage none; parting, sometimes distinct, six directions at 60°, 90°, 120° (110); brittle; fracture conchoidal, uneven.

Color red, brown, black, etc. (see varieties p. 101). Streak white. Luster vitreous. Transparent to opaque. (See p. 244.) For occurrence and varieties, see p. 101.

G. 2.65 QUARTZ (Rock Crystal), Si02.

Struct. — Prismatic hexagonal crystals striated crosswise, commonly terminated by double rhombohedron (like hexagonal pyramid); granular, disseminated, compact. Cleavage indistinct; brittle; fracture conchoidal.

Color white, colorless, and various shades to black (see varieties, p. 55). Streak white. Luster vitreous, greasy. Transparent to opaque. (See p. 262.)

In igneous rocks, gneiss, schists, sand, sandstone, quartzite; common vein mineral with many metallic ores.

74 Determinative Mineralogy [Sec. 12

H.

7 G. 2.6-2.64 CHALCEDONY (Agate, Flint, Hornstone), SiO2.

Struct. — Compact, botryoidal, mammillary, banded. Cleavage none; brittle to tough; fracture conchoidal.

Color white, grayish, brownish to black (see varieties, p. 55). Streak white. Luster waxy, vitreous, to nearly dull. Translucent to opaque. (See p. 262.)

Lining or filling cavities (agate, etc.); concretions in chalk (flint) or limestone (chert, hornstone).

7 G. 3.0-3.2 TOURMALINE, R Mg, Fe, Ca, Na, K, Li.

Struct. — Prismatic hexagonal-rhombohedral crystals, hemimorphic, curved triangular in cross-section, striated lengthwise (Fig. 58); radiating, columnar, compact. Cleavage indistinct; brittle; fracture uneven, conchoidal.

Color black (schorl) , blue (indicolite) , pink to red (rubellite), brown, green; rarely white or colorless (achroite) . Streak white. Luster vitreous, resinous. Transparent to opaque. (See pp. 222, 242, 258.)

In pegmatite, gneiss, mica schist, slate, gravels; common at contacts; with quartz, feldspars, beryl, topaz, cassiterite, fluorite.

7 G. 3.6-3.8 STAUROLITE (Staurotide), sometimes Mg, Mn.

Struct. — Prismatic orthorhombic crystals; cross twins at 60° and 90° common (Figs. 31 to 33) ; often rough. Cleavage not conspicuous, one direction lengthwise (010); brittle; fracture conchoidal, uneven.

Color yellowish brown, reddish to brownish black, weathering gray. Streak white to grayish. Luster vitreous, dull. Translucent to opaque. (See p. 260.)

In slate, schists, gneiss, with garnet, cyanite, sillimanite, tourmaline.

G. 4.5-4.8 ZIRCON, ZrSiO4; ZrO 67.2%; commonly a little Fe.

Struct. — Square tetragonal crystals with prism and pyramid; irregular lumps, disseminated grains; Cleavage indistinct; brittle; fracture uneven.

Color gray, brown, yellow, green; red transparent (hyacinth)] colorless or smoky (jargon). Streak white. Luster adamantine, vitreous. Opaque to transparent. (See p. 262.)

Minute grains in feldspathic igneous rocks; rare in crystalline limestone, gneiss, schist; with magnetite, apatite, biotite. wollastonite, titanite; in placers with gold, corundum, spinel, garnet, monazite.

G. 3.6-4.6 SPINEL, MgAl2O4; also Fe, Mn, Cr, Zn— see varieties below. Struct. — Isometric crystals (octahedrons, Fig. 1); granular, compact, disseminated. Cleavage indistinct; brittle; fracture conchoidal.

Color red, yellow, green, blue, brown, black (see varieties, p. 127). Streak white. Luster vitreous, dull. Transparent to opaque. (See p. 262.) For varieties and occurrence, see p. 127.

Secs. 12, 13] Physical Tables 75

H.

9 G. 3.9-4.1 CORUNDUM (Adamantine Spar), A1203.

Struct. — Rough hexagonal-rhombohedral crystals, prismatic, pyramidal, tabular, tapering (barrel-shaped), often striated; lamellar, granular, compact. Cleavage none; often conspicuous parting three directions at 86° and 94° (lOll); sometimes transverse parting (0001); brittle, tough when compact; fracture uneven, conchoidal.

Color white, gray, brown, to black; deep red (ruby)] blue (sapphire); black from admixture of magnetite, hematite, or spinel (emery). Streak white. Luster vitreous, adamantine. Transparent to opaque. (See p. 260.)

In peridotite, gneiss, schist, syenite, crystalline limestone; with olivine, chlorite, serpentine, magnetite, spinel, vermiculite; cyanite, diaspore, muscovite.

Section 13

Streak chalk- white, colorless, or pale colored; mineral yellow, red, or brown; distinct cleavage one direction only.

0 G. 1.4-1.5 Sassolite (Native Boric Acid), H3BO3; B2O3 56.4%.

1 Struct. — Small pearly scales; rarely thin tabular triclinic crystals. Cleavage perfect, one direction (001); greasy feel; brittle.

Color white, grayish, yellowish. Streak white. Luster pearly. Translucent. Acid taste. (See p. 228.)

In hot lagoons, fumaroles, volcanic craters, lakes, springs.

1 G. 2.3-2.8 VERMICULITE (Jeffersite, Culsageeite, etc., "Cat Gold ") Hydrated micas and chlorites; silicates of Mg, Fe, Al.

Struct. — Scaly, flaky; monoclinic pseudomorphous crystals. Cleavage perfect, one direction (001); thin flakes flexible — some very slightly so; not elastic.

Color golden yellow, yellowish brown, brownish red, yellowish green, dark green. Streak white. Luster pearly to nearly dull, metallic. Translucent to opaque. (See p. 232.)

With peridotite, serpentine, talc, chlorite, corundum, micas.

1 2.8-2.9 PYROPHYLLITE (Pencil Stone),

2 Struct. — Foliated, granular, fibrous, radial, compact; indistinct orthorhombic crystals rare. Cleavage perfect, one direction (001); fracture uneven, splintery; thin flakes flexible, not elastic; feel greasy.

Color white, apple-green, gray, yellow. Streak white. Luster pearly, dull. Translucent to opaque. (See p. 256.)

In schistose rocks with cyanite, topaz, graphite, lazulite.

1 G. 2.6-3.1 Kdmmererite (Chrome Chlorite), H, Mg, Fe, Al silicate, with 2% 5-8% Cr203.

Struct. — Foliated, scaly, compact; pseudohexagonal monoclinic plates

and pyramidal crystals. Cleavage perfect, one direction (001); thin flakes

flexible, not elastic.

76 Determinative Mineralogy [Sec. 13

H.

Color pink, rose-red, grayish red, violet. Streak white. Luster pearly. Translucent to opaque. (See pp. 236, 254.)

In peridotite and serpentine with chromite, other chlorites, talc.

1£ G. 2.3-2.4 GYPSUM (Selenite, Alabaster, Satin /Spar), CaSO4-2H2O. 2 Struct. — Granular, foliated, fibrous; earthy (gypsite); diamond-shaped monoclinic crystals with beveled edges (Figs. 38, 39). Cleavage perfect, one direction (010), two others less conspicuous (111) (100) at 90°, 66°, and 114°; brittle; thin flakes flexible; fracture conchoidal, splintery.

Color white, colorless, gray, yellow, red. Streak white. Luster vitreous; pearly on (010); silky. Transparent to opaque. (See pp. 224, 226.)

Beds and masses with limestone, clay, shale, rock salt; near volcanic vents; with anhydrite, celestite, sulphur, calcite, aragonite.

1£ G. 2.1 COPIAPITE (Misy), 17H2O; often Al and Mg.

2% Struct. — Granular, scales, crusts, powder; six-sided tabular monoclinic crystals rare. Cleavage one direction (010) ; brittle; fracture uneven, scaly, earthy.

Color yellow to greenish and brownish yellow. Streak yellowish. Luster pearly, dull. Translucent to opaque. Disagreeable metallic taste. (See p. 218.)

With iron and copper sulphates from oxidation of sulphides.

2 G. 2.9-3.0 ROSCOELITE (Vanadium Mica), approx.

V2O3 20-29%; some Mg, Fe.

Struct. — Minute micaceous scales. Color dark green to brown. Luster pearly. Translucent. (See p. 236.

In veins with quartz, gold, and tellurium; disseminated in sandstone with carnotite.

2 G. 2.7-3.0 MUSCOVITE (Common or White Mica, Potash Mica, Isinglass),

3 often a little Na, Ca, Mg, Fe, and F. Struct. — Foliated, flaky; fine scaly to fibrous (sericite, damourite)', dense

(pinite)', rarely distinct monoclinic (pseudohexagonal) crystals. Cleavage perfect, one direction (001) ; thin flakes tough, very elastic.

Color white, gray, yellowish, greenish, brownish. Streak white. Luster vitreous, pearly. Transparent to translucent. (See p. 236.)

In pegmatite, granite, gneiss, schists, contacts; with feldspars, quartz, tourmaline, beryl, garnet.

2 G/2.8-2.9 Paragonite (Soda Mica),

3 Fine scaly masses, compact; strong pearly luster. Otherwise like muscovite above. In schists with cyanite, staurolite, tourmaline, garnet, actinolite. (See p. 236.)

2 G. 2.8-3.1 BIOTITE (Black Mica, Ferromagnesian Mica

3 a little F, often Ti.

Struct. — Plates, scales; pseudohexagonal monoclinic crystals rare. Cleavage conspicuous, one direction (001); thin flakes tough, very elastic, becoming more brittle with alteration.

Sec. 13] Physical Tables 77

Color black, brownish black, greenish black, dark green. Streak white. Luster pearly, submetallic. Transparent to opaque. (See pp. 204, 220, 236.)

Common in granite, syenite, gneiss, mica schist; less common in basic igneous rocks and contacts.

2 G. 2.8-2.9 PHLOGOPITE (Amber Mica, Bronze Mica, Magnesia Mica),

3 some F and Fe.

Struct. — Plates, scales; prismatic or tabular monoclinic crystals with hexagonal or orthorhombic outlines, commonly rough. Cleavage conspicuous, one direction (001); thin flakes tough, very elastic.

Color yellowish brown, brownish red, gray to green; rarely colorless. Streak white. Luster pearly, submetallic. Translucent to transparent. (See pp. 204, 236.)

Contacts in crystalline limestone; in serpentine; with pyroxene, amphibole, serpentine, graphite, apatite, corundum.

2 G. 2.8-2.9 LEPIDOLITE (Lithia Mica), Li2O

3 3.8-5.8%.

Struct. — Foliated, scaly, compact; rarely monoclinic crystals, small tabular or prismatic. Cleavage perfect, one direction (001); thin flakes tough, elastic.

Color pink, lilac, yellowish, grayish white, white. Streak white. Luster pearly. Translucent. (See p. 236.)

In pegmatite with pink and green tourmaline, cassiterite, topaz, amblygonite, spodumene.

2 G. 2.7 THENARDITE, Na2SO4; Na20 56.3%.

3 Struct. — Orthorhombic crystals, often cross twins; granular. Cleavage one direction (001); brittle; fracture uneven.

Color white to brownish. Streak white. Luster vitreous. Transparent to translucent. Soluble in water. (See p. 224). About salt lakes and dry lake beds.

G. 2.7-2.8 Glauberite,

Struct. — Thick tabular monoclinic crystals; reniform, lamellar. Cleavage distinct, one direction (001); brittle; fracture conchoidal.

Color white, colorless, yellowish, grayish. White powdery coating forms on exposure. Streak white. Luster vitreous, greasy. Transparent to translucent. Taste slightly salty. (See p. 226.)

With halite, thenardite, mirabilite, hanksite, ulexite.

2% G. 6.2-6.5 Leadhillite,

Struct. — Tabular monoclinic (pseudohexagonal) crystals and twins; compact, lamellar. Cleavage perfect, one direction (001); rather sectile; fracture conchoidal, rarely observable.

Color white, colorless, yellow, green, gray. Streak white. Luster pearly, adamantine. Transparent to translucent. (See p. 214.)

Twins and trillings like aragonite, but very heavy. Occurs sparingly with lead ores.

78 Determinative Mineralogy [Sec. 13

H.

2$ G. 2.1-2.2 TRONA ( Urao), 2H2O.

3 Struct. — Incrusting; tabular or acicular monoclinic crystals. Cleavage one direction (100); brittle; fracture uneven.

Color white, colorless, yellowish, grayish. Streak white. Luster vitreous, pearly. Translucent. Taste alkaline. (See p. 224.)

Efflorescence; crusts on soda lakes; in beds with halite, glauberite, mirabilite, hanksite.

2£ G. 2.7-2.8 Polyhalite, K2O 15.6%.

3 Struct. — Fibrous, lamellar, compact; monoclinic (?). Cleavage distinct, one direction; brittle; fracture splintery.

Color flesh- to brick-red; yellowish red to white. Streak white, reddish to yellowish white. Luster greasy, pearly. Translucent to opaque. Taste weakly bitter and astringent. (See p. 226.)

In beds of salt, gypsum, and clay.

G. 2.3-2.4 GIBBSITE (Hydrargillite),

3 1 Struct. — Stalactitic, botryoidal, fibrous or scaly aggregates; tabular monoclinic (pseudohexagonal) crystals rare. Cleavage one direction (001), seldom observable; tough.

Color white, grayish, greenish, reddish. Streak white. Luster vitreous, pearly, dull. Translucent. (See p. 256.)

Chief constituent of some bauxite deposits; with corundum, natrolite, limonite.

3£ G. 2.1-2.2 STILBITE (Desmine, a zeolite),

4 Struct. — Sheaf-like, radial, globular; tabular monoclinic crystals, commonly in twinned groups, orthorhombic in appearance. Cleavage distinct, one direction (010) ; brittle; fracture uneven.

Color white, grayish, yellowish, red to brown. Streak white. Luster vitreous; pearly on cleavage. Translucent. (See p. 234.)

Amygdules and veins in igneous rocks, chiefly basic; in metalliferous veins; with other zeolites, prehnite, datolite, pectolite, native copper, calcite, quartz, epidote, pyrite, chalcopyrite, chlorite.

G. 2.2 HEULANDITE (a zeolite),

4 Struct. — Tabular monoclinic crystals, often look orthorhombic; diamondshaped, striated; foliated, globular, granular. Cleavage prominent, one direction (010); brittle; fracture uneven.

Color white, grayish, red, brown. Streak white. Luster vitreous; pearly Transparent to translucent. (See p. 234.)

Occurrence and associations as for stilbite, above.

G. 3.0-3.1 MARGARITE (Brittle Mica), H2CaAl4Si2O12; some Fe, Na, K. 4£ Struct. — Micaceous, scaly, granular; six-sided scales, plates (monoclinic). Cleavage perfect, one direction (001); flakes rather brittle; not elastic.

Color pink, grayish, white, yellowish. Streak white. Luster pearly on cleavage; vitreous. Translucent. (See pp. 236, 256.)

Coating or associated with corundum; also chlorite, spinel, emery, diaspore. 4i APATITE. (See p. 98.)

Sec. 13] Physical Tables 79

H.

G. 2.3-2.4 APOPHYLLITE, a little F. 5 Struct. — Square tabular or cube-like tetragonal crystals; lamellar, granular, compact. Cleavage perfect, one direction (001); brittle; fracture uneven.

Color white, greenish, yellowish, reddish. Streak white. Luster vitreous; pearly on cleavage. Transparent to nearly opaque. (See p. 234.)

Amygdules and veins in igneous rocks, chiefly basic; in metalliferous veins; with zeolites, prehnite, datolite, pectolite, native copper, calcite, quartz, epidote, pyrite, chalcopyrite, chlorite.

5 G. 3.3-3.5 HYPERSTHENE (a pyroxene), sometimes Al.

6 Struct. — Foliated, cleavable, granular; orthorhombic crystals rare. Cleavage perfect, one direction (010), less distinct, two directions (110) at 46°, 88°, 92°, and 134°; brittle; fracture uneven.

Color grayish, greenish, and brownish black to bronze. Streak brownish , gray, grayish white. Luster metalloidal bronzy, pearly. Opaque to translucent. (See pp. 222, 258.)

In basic igneous rocks with plagioclase feldspars, olivine, amphibole, pyroxene, magnetite, titanite; seldom with quartz.

PYROXENE. (See p. 83.)

6 G. 3.2-3.4 ZOISITE, often some Fe. 61 Struct. — Columnar, bladed, fibrous, compact; prismatic orthorhombic crystals striated lengthwise, without terminations. Cleavage conspicuous, one direction lengthwise (010) ; brittle; fracture uneven.

Color gray, yellowish brown, greenish; also red (thulite). Streak white. Luster vitreous; pearly on cleavage. Transparent to opaque. (See p. 246.) In crystalline schists with hornblende, vesuvianite, cyanite, epidote, garnet, feldspars, quartz.

6 G. 3.2-3.5 EPIDOTE (Pistacite),

7 Struct. — Long monoclinic crystals striated lengthwise, commonly terminated by two sloping faces ; columnar, divergent acicular, granular. Cleavage distinct, one direction lengthwise (001); brittle; fracture uneven.

Color yellowish green to brown and black, gray, yellow, red. Streak white to grayish. Luster vitreous. Transparent to opaque. (See pp. 222, 246.)

In gneiss, schists, crystalline limestone, greenstone; with garnet, magnetite, chlorite, native copper, zeolites.

6 G. 3.2-3.3 SILLIMANITE (Fibrolite), Al2Si05, or

7 Struct. — Fibrous, columnar, radiating; slender orthorhombic crystals without terminations. Cleavage one direction lengthwise (010); brittle; fracture splintery, uneven.

Color grayish white, hair-brown, greenish. Streak white. Luster vitreous, silky. Transparent to translucent. (See p. 260.)

In gneiss; in contacts of aluminous rocks, with andalusite, cordierite, garnets, corundum.

6 G. 3.3-3.5 DIASPORE, A1O- OH; Al 45%; sometimes Fe.

7 Struct. — Scaly, bladed, fibrous; columnar and tabular orthorhombic crystals rare. Cleavage distinct, one direction (010); brittle; fracture conchoidal.

80 Determinative Mineralogy [Secs. 13, 14

H.

Color white, grayish, greenish, hair-brown, yellow, colorless. Streak white. Luster vitreous, pearly. Transparent to opaque. (See p. 260.) With corundum, emery, dolomite, margarite, chlorite, magnetite.

6 G. 3.3-3.4 AXINITE, sometimes Mn, Fe, Mg.

7 Struct. — Tabular wedge-shaped triclinic crystals (Fig. 45); lamellar, granular. Cleavage distinct, one direction (010) ; brittle; fracture conchoidal.

Color clove-brown, yellow, greenish, grayish blue, gray. Streak white. Luster vitreous. Transparent to translucent. (See p. 242.) In veins with quartz, feldspars, hornblende, chlorite.

7 G. 2.6-2.7 CORDIERITE (lolite, Dichroite, Water Sapphire),

Struct. — Short six- or twelve-sided orthorhombic (pseudohexagonal) crystals; granular, compact, disseminated. Cleavage one direction lengthwise (010); parting sometimes conspicuous crosswise (001); brittle; fracture uneven, conchbidal.

Color light to dark smoky blue, gray, violet, yellow. Resembles blue quartz; often altering to dull green chlorite; transparent varieties show marked differences in color in different directions. Streak white. Luster vitreous, dull. Transparent to translucent. (See pp. 244, 260.)

In schists, gneiss, sometimes in granite; with quartz, feldspars, hornblende, tourmaline, andalusite, sillimanite, garnet.

8 G. 3.4-3.6 Topaz,

Struct. — Prismatic orthorhombic crystals striated lengthwise; granular, pebbles, compact. Cleavage perfect, one direction crosswise (001); brittle; fracture conchoidal, uneven.

Color white, colorless, yellow, pink, bluish, greenish. Streak white. Luster vitreous. Transparent to opaque. (See p. 260.)

Veins in pegmatite, rhyolite, granite; contacts; placers; with tourmaline, cassiterite, apatite, fluorite, beryl, garnet.

Section 14

Streak chalk- white, colorless, or pale colored; mineral yellow, red, or brown; distinct cleavage two directions.

G. 3.7 STRONTIANITE (Slrontian Spar), SrCO3; SrO 70.1%; some-

4 times Ca.

Struct. — Chisel- or spear-shaped orthorhombic crystals, pseudohexagonal prisms; columnar, acicular, fibrous, divergent; granular, compact. Cleavage distinct, two directions at 63° and 117° (110); brittle; fracture uneven.

Color white, colorless, grayish, greenish, yellowish. Streak white. Luster vitreous, greasy. Transparent to translucent. (See p. 246.)

In ore deposits with galena, barite, calcite, celestite, fluorite, pyrite; veins in limestone, chalk, marl.

Sec. 14] Physical Tables 81

H.

4 G.2.2 Phillipsite (a zeolite), often Na.

4j Struct. — Monoclinic penetration twins, often like orthorhombic or tetragonal; radial tufts or spheres. Cleavage two directions at 90° (010) (001); brittle; fracture uneven.

Color white, reddish. Streak white. Luster vitreous. Translucent to opaque. (See p. 232.)

Amygdules and veins in igneous rocks, chiefly basic; in metalliferous veins; with other zeolites, prehnite, datolite, pectolite, native copper, calcite, quartz, epidote, pyrite, chalcopyrite, chlorite.

G. 2.4-2.5 HARMOTOME (a zeolite), some Na and K.

Struct. — Penetration twins, etc. (monoclinic), like phillipsite above, with cleavage, fracture, etc., the same.

Color white, grayish, yellow, red brown. Streak white. Luster vitreous. Translucent. (See pp. 232, 244.)

Occurrence and associations as for phillipsite, above.

4 G. 4.4-4.6 XENOTIME, YPO4; also Er, Ce, Th, etc.

5 Struct. — Tetragonal crystals (prism, pyramid); compact, disseminated, rolled grains. Cleavage distinct, two directions at 90° (110); brittle; fracture uneven, splintery.

Color yellow, brown, red, pale gray. Streak pale brown, yellowish, reddish. Luster greasy, vitreous. Translucent to opaque. (See p. 256.)

Like zircon but softer. In pegmatite and granitic rocks with zircon, rutile; in sands.

4£ G. 3.4-3.5 CALAMINE (Electric Calamine, Hemimorphite), 5 Zn 54.2%.

Struct. — Tabular orthorhombic-hemimorphic crystals, commonly divergent cockscomb groups; mammillary, stalactitic, granular. Cleavage two directions lengthwise at 76° and 104° (110); brittle; fracture uneven, conchoidal.

Color white, colorless, yellowish, brownish, greenish, bluish. Streak white. Luster vitreous, adamantine, dull. Transparent to translucent. (See p. 252.)

In oxidized zinc ores, usually in limestone or clay, with smithsonite, cerusite, anglesite, galena, sphalerite, calcite, limonite.

4£ G. 2.8-2.9 WOLLASTONITE (a pyroxene), (Tabular Spar), CaSiO3. 5 Struct. — Granular, fibrous, compact, cleavable; tabular monoclinic crystals. Cleavage distinct, two directions at 84£° and 95£° (100) (001); brittle; fracture uneven.

Color white, grayish, yellowish, reddish, brownish. Streak white. Luster vitreous, silky; pearly on cleavage. Translucent to opaque. (See p. 234.) In limestone contacts with pyroxene, tremolite, garnet, vesuvianite, epidote, graphite.

82 Determinative Mineralogy [Sec. 14

H.

5 G. 2.2-2.3 NATROLITE (Needle Zeolite,}

Struct. — Slender orthorhombic (pseudotetragonal) crystals; fibrous, radial, granular, compact. Cleavage two directions lengthwise at 88° and 91° (110); brittle; fracture uneven.

Color white, colorless, grayish, reddish, yellowish. Streak white. Luster vitreous, silky. Transparent to translucent. (See p. 230.)

Amygdules and veins in igneous rocks, chiefly basic; metalliferous veins; with other zeolites, prehnite, datolite, pectolite, native copper, calcite, quartz, epidote, pyrite, chalcopyrite, chlorite.

5 G. 3.4-3.6 TITANITE (Sphene), CaSiTiO5; commonly a little Fe.

Struct. — Tabular or wedge-shaped monoclinic crystals; lamellar, compact. Cleavage distinct, two directions at 66£° and 113|° (110); parting often distinct four directions at 54° and 126° (221); brittle; fracture conchoidal.

Color brown to black, yellow, gray, green: rarely rose-red. Streak white. Luster vitreous, resinous, adamantine. Transparent to opaque. (See pp. 234, 246.)

Accessory in many igneous rocks; in gneiss, chlorite schist, crystalline limestone; with chlorite, iron oxides, pyroxene, amphibole, zircon, apatite, feldspars, quartz, rutile.

5 G. 2.9-3 .4 HORNBLENDE (an amphibole), with

6 A12O3 up to 15 or 20%, also ferric iron, alkalies (Na, K), and often H and F.

Struct. — Granular, columnar, fibrous, radiated; long prismatic monoclinic crystals, often rhombohedron-like terminations; prism angle 124°; some prisms short, six sided. Cleavage perfect, two directions lengthwise at 56° and 124° (110); brittle; fracture uneven, splintery.

Color green, black, brown, gray. Streak brown, green, yellow, gray, white. Luster submetallic, vitreous, pearly, silky. Translucent to opaque. (See pp. 222, 238.)

Common in igneous and metamorphic rocks with feldspars, pyroxenes, chlorite, quartz, calcite.

5 G. 2.9-3.1 TREMOLITE (Grammatite, an amphibole),

6 Struct. — Bladed, columnar, fibrous, compact; bladed monoclinic crystals without terminations; prism angle 124°. Cleavage conspicuous, two directions lengthwise at 56° and 124° (110); brittle; small fibers flexible; fracture uneven. Nephrite or jade, in part tremolite, is dense, compact, tough.

Color white to dark gray, yellowish, colorless. Streak white. Luster vitreous, silky, pearly. Transparent to opaque. (See p. 238.)

In limestone, dolomite, schist; common at contacts; with pyroxene, garnet, vesuvianite, epidote, wollastonite.

5 G. 3.0-3.2 Anthophyllite (an amphibole), sometimes Al

6 (Gedrite).

Struct. — Lamellar, columnar, fibrous; prismatic orthorhombic crystals rare. Cleavage two directions lengthwise at 54° and 125|° (110); brittle; fracture splintery; small fibers flexible (asbestos}.

Sec. 14] Physical Tables 83

H.

Color gray, clove-brown, greenish to emerald. Streak white. Luster vitreous, pearly, silky, sometimes metalloidal. Translucent to opaque. (See pp. 222, 238, 258.)

In schists with talc, hornblende, chlorite, mica.

5 G. 3.2-3.6 PYROXENE, ranging from Diopside,

6 to Hedenbergite, often some Al, Mn, and Na.

AUGITE (a pyroxene), like common pyroxene above, with A12O3 up to 15 or 20%; sometimes alkali metals, Na and K.

Struct. — Granular, columnar, rarely fibrous; lamellar (diallage)', thick monoclinic prisms four- or eight-sided (Figs. 40, 41). Cleavage two directions lengthwise at 87° and 93° (110), sometimes distinct; parting crosswise (001), often prominent; diallage has fine lamellar parting one direction lengthwise (100); brittle; fracture uneven.

Color bright to dark green, grayish green, black, brown. Streak greenish, brownish, grayish to white. Luster vitreous, submetallic, dull. Transparent to opaque. (See pp. 220, 222, 240.)

Common in basic igneous rocks; in crystalline limestones with garnet, chlorite, amphibole, wollastonite, magnetite, pyrite.

5 G. 3.1-3.3 ENSTATITE (a pyroxene), FeO up to 12%.

6 Struct. — Lamellar, columnar, fibrous, compact; prismatic orthorhombic crystals rare. Cleavage distinct, two directions at 88° and 92° (110); parting one direction (010), bisecting cleavage angle; brittle; fracture uneven.

Color grayish white, yellowish, greenish, to olive-green and brown. Streak white. Luster vitreous, pearly; submetallic, bronzy (bronzite). Translucent to opaque. (See pp. 240, 258.)

In basic igneous rocks (gabbro, peridotite) and serpentine.

5£ G. 4.0-4.1 Tephroile, Mn2SiO4; commonly also Mg and a little Fe. 6 Struct. — Cleavable, granular, compact; orthorhombic crystals rare. Cleavage distinct, two directions at 90°; brittle; fracture conchoidal, uneven. Color ash-gray, flesh-red, brown. Streak pale gray. Luster vitreous, greasy. Translucent to opaque. (See p. 230.)

In crystalline limestone with zincite, willemite, franklinite, rhodonite (Franklin, N, J.); with other manganese minerals.

G. 3.4-3.7 RHODONITE, MnSiO3; often Ca, Fe; sometimes Zn (Fow- 6£ lerite).

Struct. — Granular, cleavable, compact; triclinic crystals, tabular, commonly rough, with rounded edges. Cleavage distinct, two directions at 92° and 87|° (110); brittle, tough when compact; fracture conchoidal, uneven. Color brownish red, flesh-red, pink; sometimes yellowish or greenish; may tarnish brown or black on exposure. Streak white. Luster vitreous. Transparent to opaque. (See p. 240.)

In veins; in crystalline limestone with willemite, franklinite, zincite.

84 Determinative Mineralogy [Sec. 14

H.

6 G. 3.0-3.1 AMBLYGONITE, Li2O 10.1%; sometimes Na, OH.

Struct. — Cleavable, compact, columnar; triclinic crystals rare. Cleavage conspicuous, one direction (001), less distinct in another direction at 83° and 97° to this (100); brittle; fracture uneven.

Color white, pale gray, green, blue, yellow, brown. Streak white. Luster vitreous; pearly on (001). Translucent to opaque. (See p. 242.)

Resembles feldspars, but heavier. Rare in pegmatite with tourmaline, lepidolite, apatite, topaz.

6 G. 2.5-2.6 ORTHOCLASE (Potash Feldspar}, KAlSi3O8; K2O 16.9%; 6 1 often Na

Struct. — Cleavable, granular, disseminated grains; prismatic and tabular monoclinic crystals and twins (Figs. 42 to 44). Cleavage distinct, two directions at 90° (010) (001); brittle; fracture conchoidal, uneven.

Color white, red, gray, green, colorless. Streak white. Luster vitreous; often pearly on cleavage. Transparent to opaque. (See p. 238.)

In many igneous and metamorphic rocks; in veins and contacts; with quartz, other feldspars, mica, hornblende, pyroxene; in pegmatite with beryl, topaz, tourmaline. For description of varieties, see p. 37.

6 G. 2.6-2.8 PLAGIOCLASE (Soda-lime or Lime-soda Feldspar), ranging 6£ from NaAlSi3O8 (ab) to CaAl2Si2O8 (an); generally also

some K.

Struct. — Lamellar, granular, disseminated; small triclinic crystals (Fig. 46). Cleavage distinct, two directions at 86°-86£° and 94°-93£° (001) (010); often striations on one cleavage; cleavage often curved; brittle; fracture uneven.

Color white, colorless, gray, green, bluish, reddish; sometimes play of colors — blue, green, yellow, red. Streak white. Luster vitreous; often pearly on cleavage. Transparent to opaque, sometimes opalescent (moonstone), or with bright reddish or yellowish reflections from included scales (aventurine feldspar, or sunstone). (See p. 238.) For varieties, see p. 37.

In igneous rocks, gneisses, schists, with other feldspars, quartz, mica, chlorite, zeolites; sometimes in veins.

6 G. 3.5-3.6 Aegirite (Aegirine, Acmite] a pyroxene), Struct. — Long prismatic monoclinic crystals with terminations blunt (aegirite) or sharp (acmile)', acicular, fibrous. Cleavage distinct, two directions at 87° and 93° (110); brittle; fracture uneven.

Color greenish black to reddish and brownish black; acmite often green interior, brown exterior. Streak pale yellowish gray. Luster vitreous, resinous. Translucent to opaque. (See pp. 222, 240.)

In igneous rocks rich in soda and iron — aegirite granite, nephelite syenite, phonolite, pegmatite.

6 G. 3.1-3.2 SPODUMENE (a pyroxene), Li2O 8.4%; some Na.

7 Struct. — Cleavable, columnar, compact; rough prismatic or flattened monoclinic crystals, striated lengthwise. Cleavage conspicuous, two directions lengthwise at 87° and 93° (110) ; parting one direction sometimes prominent, bisecting larger cleavage angle (100) ; brittle; fracture uneven; splintery.

Secs. 14, 15] Physical Tables 85

H.

Color white, gray, yellowish; emerald-green (hiddenite) ; pink to purple (kunzite). Streak white. Luster vitreous, pearly. Transparent to opaque. (See pp. 240, 242.)

In pegmatites with tourmaline, lepidolite, beryl, amblygonite, cassiterite.

RUTILE. (See p. 100.)

6$ G. 3.2-3.6 OLIVINE (Chrysolite, Peridot), ranging from 7 Forsterite, Mg2SiO4, to Fayalite, Fe2SiO4; sometimes a little

Ni, Sn, Ti.

Struct. — Granular, disseminated; prismatic or tabular orthorhombic crystals (Fig. 36) rare. Cleavage indistinct, two directions at 90° (100) (010); brittle; fracture conchoidal, uneven.

Color yellowish green, yellowish brown, reddish. Streak white, yellowish white. Luster vitreous. Transparent to translucent. (See p. 252.)

In basic igneous rocks (gabbro, basalt, peridotite) with augite, chromite, corundum, spinel, pyrope; rarely in crystalline dolomite.

G. 3.1-3.2 ANDALUSITE (Chiastoliie, Made), Al2Si05, or 7 1 Struct. — Columnar, granular, disseminated; rough orthorhombic prisms, nearly square. Cleavage distinct, two directions at 89° and 91° (110) ; brittle; fracture uneven.

Color white, pink, reddish brown, olive-green; sometimes black and white cross or checkered pattern on cross-fracture (chiastolite, or made)] Streak white. Luster vitreous, dull. Translucent to opaque. (See p. 260.)

In slate, schists, and gneiss, with sillimanite, garnet, biotite, tourmaline, cordierite.

G. 3.5-3.8 CHRYSOBERYL (Cymophane) , G1A1204.

Struct. — Tabular orthorhombic crystals, heart-shaped or pseudohexagonal twins, disseminated plates. Cleavage two directions at 60° and 120° (Oil); brittle; fracture uneven, conchoidal.

Color yellowish green, deep green, greenish white, greenish brown, yellow. Streak white. Luster vitreous, greasy. Transparent to translucent. Alexandrite, the deep green variety, is red by gas or lamp light; cat's eye is yellowish green, opalescent. (See p. 260.)

In granite, gneiss, mica schist, placers; with beryl, garnet, tourmaline, sillimanite.

Section 15

Streak chalk-white, colorless, or pale colored; mineral yellow, red, or brown; distinct cleavage three or more directions.

li G. 2.3-2.4 GYPSUM (Selenite, Alabaster, Satin Spar), CaSO4-2H2O.

2 Struct. — Granular, foliated, fibrous; earthy (gypsite)', diamond-shaped monoclinic crystals with beveled edges (Figs. 38, 39). Cleavage perfect, one direction (010), two others less conspicuous (111) (100) at 90°, 66°, and 114°; brittle, thin flakes flexible; fracture conchoidal, splintery.

86 Determinative Mineralogy [Sec. 15

H.

Color white, colorless, gray, yellow, red. Streak white. Luster vitreous; pearly on (010); silky. Transparent to opaque. (See pp. 224, 226.)

Beds and masses with limestone, clay, shale, rock salt; near volcanic vents; with anhydrite, celestite, sulphur, calcite, aragonite.

3 G. 2.1-2.6 HALITE (Common Salt, Rock Salt}, NaCl; Na 60.6%; often 3f Ca and Mg.

Struct. — Granular, cleavable, compact; isometric crystals (cubes, Fig. 5). Cleavage distinct, three directions at 90° (100); brittle; fracture conchoidal. Color white, colorless, grayish, reddish, bluish. Streak white. Luster vitreous. Transparent to translucent. Taste salty. (See p. 224.)

Beds in sedimentary strata with gypsum, anhydrite, sylvite, calcite, clay, sand; in dry lakes; in brines. (Compare Cryolite, p. 95.)

3 G. 1.9-2.0 SYLVITE, KC1; K 52.4%; sometimes Na.

3 1 Struct. — Granular, compact; isometric crystals (cubes, Fig. 5) . Cleavage distinct, three directions at 90° (100); brittle; fracture conchoidal.

Color white, colorless, grayish, bluish, reddish. Streak white. Luster vitreous. Transparent to translucent. Taste salty, bitter. Becomes damp in moist air. (See p. 224.)

In salt deposits; with halite, kainite, carnallite.

2$ G. 2.0-2.2 KAINITE, KMgClS04-3H2O; K 18.9%.

3 Struct. — Compact, fine granular; rarely tabular or prismatic monoclinic crystals. Cleavage distinct, three directions at 39£°, 101 £°, and 140° (100) (110), brittle; fracture uneven.

Color white, colorless, reddish. Streak white. Luster vitreous. Transparent to translucent. Taste salty, bitter, astringent. (See p. 224.) In beds with halite, sylvite, gypsum, anhydrite.

2$ G. 4.3-4.6 BARITE (Baryles, Heavy Spar), BaSO4; sometimes Ca and Sr. Struct. — Tabular and prismatic orthorhombic crystals, divergent groups; compact, lamellar, fibrous. Cleavage distinct, three directions at 78|°, 90°, and 10U° (001) (110); brittle; fracture uneven.

Color white, colorless, light shades of yellow, brown, red, blue. Streak white. Luster vitreous, pearly. Transparent to opaque. (See p. 226.)

In veins with galena, sphalerite, fluorite, chalcopyrite; in limestones and residual clays with manganese and iron oxides.

3 G. 2.7 CALCITE (Calc Spar), CaCO3; often Mg, Fe, Mn, sometimes Pb.

Struct. — Hexagonal-rhombohedral crystals, prismatic, scalenohedral, rhombohedral, tabular, or acicular in habit (Figs. 52 to 57); rarely twins; cleavable, granular, stalactitic, oolitic, earthy. Cleavage perfect, three directions at 75° and 105° (lOll): brittle; fracture conchoidal. seldom observed.

Color white, colorless, pale shades of gray, yellow, red, green, blue, violet; brown to black when impure. Streak white. Luster vitreous, dull. Transparent to opaque. (See p. 246.)

Chief constituent of limestone, marble, chalk, calcareous marl; in veins with metallic ores, quartz, pyrite, zeolites, (For varieties see p. 40.)

Sec. 15] Physical Tables 87

H.

3 G. 6.1-G.4 ANGLESITE (Lead Vitriol') PbSO4; Pb 68.3%.

Struct. — Orthorhombic crystals; granular, compact. Cleavage three directions at 76°, 90°, and 104° (001) (110), not conspicuous; brittle; fracture conchoidal.

Color white, colorless, gray, brown, green. Streak white. Luster adamantine, vitreous. Transparent to translucent. (See p. 214.)

In oxidized parts of ore deposits with lead, zinc, and iron minerals.

3 G. 2.9-3.0 ANHYDRITE (Anhydrous Gypsum), CaSO4. 3 1 Struct. — Granular, compact, fibrous, cleavable; rarely orthorhombic crystals. Cleavage distinct, three directions at 90° (001) (100) (010); brittle; fracture conchoidal.

Color white, grayish, bluish, reddish, to brick-red. Streak white to grayish. Luster vitreous; pearly on (001). Translucent to opaque. (See p. 226.)

In limestones, shales, salt deposits; with nalite, gypsum, calcite.

3 G. 3.9-4.0 CELESTITE, SrSO4; sometimes Ca and Ba.

Struct. — Tabular or prismatic orthorhombic crystals (Fig. 37); fibrous, cleavable, rarely granular. Cleavage distinct, three directions at 76°. 90°, and 104° (001) (110); brittle; fracture uneven.

Color white, colorless, bluish, reddish. Streak white. Luster vitreous, pearly. Transparent to translucent. (See p. 226.)

In limestones and shales with gypsum, halite, sulphur, galena, aragonite.

3£ G. 2.8-2.9 DOLOMITE sometimes Fe and Mn (much Fe,

4 Ankerite).

Struct. — Granular, cleavable, compact; hexagonal-rhombohedral crystals, faces often curved (pearl spar). Cleavage perfect, three directions at 74° and 106° (lOll); brittle; fracture conchoidal, uneven.

Color white, colorless, gray, red, green, brown, black. Streak white. Luster vitreous, pearly. Transparent to opaque. (See p. 246.)

Extensive strata as dolomitic limestone and marble; gangue with ores of lead, zinc, etc.; with serpentine, talc, gypsum, and ordinary limestones.

G. 3.8-3.9 SIDERITE (Spathic Iron, Chalybite, Clay Ironstone, Black 4 Band Ore), FeCO3; Fe 48.3%; sometimes Mg, Mn, Ca.

Struct. — Granular, cleavable, compact; hexagonal-rhombohedral crystals, curved and saddle-shaped common. Cleavage perfect, three directions at 73° and 107° (lOll); brittle; fracture uneven.

Color gray, yellow, brown, black, sometimes white. Streak white, pale yellow. Luster vitreous, pearly, dull. Translucent to opaque. (See pp. 218, 248.)

In veins with silver minerals, pyrite, and other sulphides, cryolite; beds and concretions in limestone, shale, coal.

3£ G. 2.9-3.0 ARAGONITE (Flos Ferri), CaCO3; sometimes Sr and Pb.

4 Struct. — Chisel- or spear-shaped orthorhombic crystals, pseudohexagonal prisms; acicular, columnar, stalactitic, coral-like. Cleavage three directions at 64°, 90°, and 116° (110) (010); brittle; fracture conchoidal.

88 Determinative Mineralogy [Sec. 15

H.

Color white, gray, yellow, pale green, violet. Streak white. Luster vitreous, resinous. Transparent to translucent. (See p. 246.)

In gypsum beds, basalt, serpentine, beds of limonite and siderite; with celestite, sulphur, metallic sulphides, zeolites; constitutes some shells (pearly layers of many) and coral.

G. 3.9-4.1 SPHALERITE (Blende, Zinc Blende, Jack, Black Jack, Rosin

4 Jack}, ZnS; Zn 67%; may be replaced by Fe up to 18%.

Struct. — Cleavable masses, granular, compact, botryoidal; rounded

isometric-tetrahedral crystals. Cleavage pronounced, six directions at 60°,

90°, and 120° (110); brittle; fracture conchoidal.

Color yellow, brown, red, green, black; rarely white or pale gray (cleiophane). Streak white, light to dark brown. Luster resinous, adamantine, submetallic. Transparent to opaque. (See pp. 200, 228, 250.)

Ore deposits and veins with galena, pyrite, chalcopyrite, fluorite, barite; also in limestones.

G. 2.2-2.3 LAUMONTITE (a zeolite),

4 Struct. — Radial, divergent, columnar; prismatic monoclinic crystals with

oblique terminations. Cleavage three directions lengthwise at 86°, 94°. and

137° (110) (010); brittle, friable; fracture uneven, earthy.

Color white, yellowish, grayish, reddish. Streak white. Luster vitreous,

pearly. Transparent to opaque. Becomes dull, opaque, and powdery on

exposure. (See p. 230.)

Amygdules and veins in igneous rocks, chiefly basic; in metalliferous

veins; with other zeolites, prehnite, datolite, pectolite, native copper, calcite,

quartz, epidote. pyrite, chalcopyrite, chlorite.

3£ G. 3.4-3.6 RHODOCHROSITE (Dialogite), MnC03; Mn 47.8%; some- 4£ times Fe, Ca, Mg.

Struct. — Cleavable, granular, compact, botryoidal, incrusting; hexagonalrhombohedral crystals rare, commonly with curved faces. Cleavage conspicuous, three directions at 73° and 107° (1011); brittle; fracture uneven.

Color reddish white, rose-red, dark red, brown; brown to black on exposure. Streak white. Luster vitreous, pearly. Transparent to translucent. (See p. 248.)

In veins with other manganese minerals, ores of silver, lead, and copper; pyrite.

3£ G. 3.0-3.1 MAGNESITE, MgCO3; sometimes much Fe (Breunnerite; also Mn.

Struct. — Compact like unglazed porcelain, granular, cleavable; rarely hexagonal-rhombohedral crystals. Cleavage conspicuous, three directions at 72|° and 107|° (lOll); tough to brittle; fracture conchoidal.

Color white, yellowish, grayish, brown. Streak white. Luster vitreous, dull. Transparent to opaque. (See p. 248.)

Forming extensive beds; disseminated in talc and chlorite schists; veins in serpentine, dolomite, limestone; with gypsum.

Sec. 15] Physical Tables 89

H.

4 G. 3.0-3.2 FLUORITE (Fluor Spar, Blue John), CaF2; F 48.9%; sometimes Cl.

Struct. — Isometric crystals (cubes, Fig. 5), penetration twins; cleavable masses, granular, columnar. Cleavage perfect, four directions at 70£° and 109|° (111); brittle; fracture uneven.

Color violet, blue, green, yellow, colorless, brown. Streak white. Luster vitreous. Transparent to translucent. (See p. 226.)

Common in veins and contacts with galena, sphalerite, calcite, barite, cassiterite, apatite, topaz, lepidolite; in limestones; rare in igneous rocks.

4 G. 2.0-2.2 CHABAZITE (a zeolite), often K, Na,

5 Ba, Sr.

Struct. — Hexagonal-rhombohedral crystals (cube-like rhombohedrons), also modified forms, twins; compact. Cleavage distinct, three directions at 85° and 95° (lOll); brittle; fracture uneven.

Color white, yellow, flesh-red. Streak white. Luster vitreous. Transparent to translucent. (See p. 234.)

Amygdules and veins in igneous rocks, chiefly basic; in metalliferous veins; with other zeolites, prehnite, datolite, pectolite, native copper, calcite, quartz, epidote, pyrite, chalcopyrite, chlorite.

4£ G. 5.9-6.2 SCHEELITE, CaWO4; WO380.6%; some Mo; sometimes Cu 5 (Cuproscheelite) .

Struct. — Small pyramidal tetragonal crystals resembling octahedrons, sometimes tabular; incrusting, granular, compact. Cleavage distinct, four directions at 80°, 110°, and 130|° (111); brittle; fracture conchoidal, uneven. Color white, yellow, brownish, greenish, reddish. Streak white to yellowish. Luster greasy, adamantine. Transparent to translucent. (See pp. 234, 254, 258.)

In veins and contacts with quartz, cassiterite, topaz, fluorite, apatite, molybdenite.

5 G. 4.3-4.5 SMITHSONITE (Dry Bone; Calamine, in England), ZnCO3; Zn52.1%.

Struct. — Mammillary, stalactitic, incrusting, cellular (dry bone)', rarely small hexagonal-rhombohedral crystals with cleavage distinct, three directions at 72° and 108° (lOll); brittle; fracture uneven, splintery.

Color white, grayish, colorless, greenish, blue, pink, brown. Streak white. Luster vitreous, adamantine, pearly, dull. Transparent to opaque, (See p. 248.)

In oxidized zinc ores, usually in limestone or clay, with calamine, cerusite, anglesite, galena, sphalerite, calcite, limonite.

5 G. 3.2-3.6 PYROXENE, ranging from Diopside,

6 to Hedenbergite, often some Al, Mn, and Na.

AUGITE (a pyroxene), like common pyroxene above, with

A12O3 up to 15 or 20%; sometimes alkali metals, Na and K.

Struct. — Granular, columnar, rarely fibrous; lamellar (diallage); thick

90 Determinative Mineralogy [Sec. 1J

H.

monoclinic prisms four- or eight-sided (Figs. 40, 41). Cleavage two directions lengthwise at 87° and 93° (110), sometimes distinct; parting crosswise (001), often prominent; diallage has fine lamellar parting one direction lengthwise (100); brittle; fracture uneven.

Color bright to dark green, grayish green, black, brown. Streak greenish, brownish, grayish to white. Luster vitreous, submetallic, dull. Transparent to opaque. (See pp. 220, 222, 240.)

Common in basic igneous rocks; in crystalline limestones with garnet, chlorite, amphibole, wollastonite, magnetite, pyrite.

5 G. 3.1-3.3 ENSTATITE (a pyroxene), FeO up to 12%. .

6 Struct. — Lamellar, columnar, fibrous, compact; prismatic orthorhombic crystals rare. Cleavage distinct, two directions at 88° and 92° (110); parting one direction (010), bisecting cleavage angle; brittle; fracture uneven.

Color grayish white, yellowish, greenish, to olive-green and brown. Streak white. Luster vitreous, pearly; submetallic, bronzy (bronzite). Translucent to opaque. (See pp. 240, 258.)

In basic igneous rocks (gabbro, peridotite) and serpentine.

5 G. 2.5-2.6 NEPHELITE ( Nepheline, Elaeolite; a feldspathoid), NaAlSiO4;

6 also K2O up to 7%.

Struct. — Compact, disseminated, grains; small hexagonal crystals rare. Cleavage distinct, three directions at 60° and 120° (lOlO); brittle; fracture conchoidal, uneven.

Color reddish, brownish, greenish, gray, white, colorless. Streak white. Luster greasy, vitreous. Transparent to opaque. (See p. 232.)

In lavas and granular igneous rocks with feldspars, sodalite, cancrinite, biotite, zircon, corundum; not with quartz.

5 G. 2.6-2.8 Wernerite

6 Struct. — Stout prismatic tetragonal crystals; compact, fibrous, granular. Cleavage three directions lengthwise at 45° and 90° (100) (110), not conspicuous; brittle; fracture conchoidal, uneven.

Color white, gray, greenish, plush, reddish/ Streak white. Luster vitreous, greasy. Translucent to opaque. (See pp. 234, 244.)

In crystalline limestones and schists with pyroxenes, amphiboles, apatite, garnet, biotite.

5 G. 3.9-4.2 WILLEMITE, Zn2SiO4; Zn 58%; may contain Mn (Troostite)

6 some Fe.

Struct. — Compact granular, disseminated; prismatic hexagonal-rhombohedral crystals rare. Cleavage distinct, three directions at 60° and 120° (1120); brittle; fracture conchoidal, uneven.

Color yellow, green, red, brown, white. Streak white. Luster vitreous. Transparent to opaque. (See pp. 232, 252.)

In crystalline limestone with franklinite, zincite, rhodonite.

Sec. 15] Physical Tables 91

H.

5 G. 3.3-3.5 HYPERSTHENE (a pyroxene), sometimes Al.

6 Struct. — Foliated, cleavable, granular; orthorhombic crystals rare. Cleavage perfect, one direction (010), less distinct, two directions (110) at 46°, 88°, 92°, and 134°; brittle; fracture uneven.

Color grayish, greenish, and brownish black to bronze. Streak brownish gray, grayish white. Luster metalloidal bronzy, pearly. Opaque to translucent. (See pp. 222, 258.)

In basic igneous rocks with plagioclase feldspars, olivine, amphibole, pyroxene, magnetite, titanite; seldom with quartz.

5 G. 2.4-2.5 CANCRINITE (a feldspathoid),

6 Struct. — Compact, lamellar, columnar, disseminated; prismatic hexagonal crystals rare. Cleavage distinct, three directions at 60° and 120° (lOll); brittle; fracture uneven.

Color white, gray, yellow, green, blue, reddish. Streak white. Luster vitreous, greasy, pearly. Transparent to translucent. (See p. 230.)

In granular igneous rocks with nephelite, sodalite, biotite, feldspars, titanite; not with quartz.

5£ G. 3.8-3.9 Octahedrite (Anatase), Ti02; Ti 60%.

6 Struct. — Tetragonal crystals, pyramidal, tabular, rarely prismatic. Cleavage distinct, five directions at 82°, 111°, and 136£° (111) (001); brittle; fracture uneven.

Color brown, dark blue, black. Streak white, pale gray. Luster adamantine, metallic. Translucent to opaque. (See pp. 210, 262.)

Minute crystals in granular igneous rocks; in gneiss, schists, quartzite, limestone; with brookite, rutile, ilmenite, biotite, adularia, titanite, gold.

5£ G. 4.0 Perovskite (Perofskite), CaTiO3; some Fe.

6 Struct. — Isometric (or pseudoisometric) crystals, commonly cubes (Fig. 5), often highly modified and striated; reniform aggregates, rounded grains. Cleavage distinct, three directions at 90° (100); brittle; fracture uneven.

Color pale yellow to orange-yellow, reddish brown, grayish black. Streak white, grayish. Luster adamantine, submetallic. Transparent to opaque. (See pp. 210, 258.)

In schists, crystalline limestone, serpentine, basic igneous rocks; with chlorite, magnetite, garnet, vesuvianite, rutile, ilmenite, corundum.

6£ G. 3.4-4.3 GARNET, R" Ca, Mg, Fe, Mn, Ti; R'"=A1, Fe, Cr,Ti.

Struct. — Isometric crystals (dodecahedrons, trapezohedrons, Figs. 3, 7, 8) ; granular, lamellar, compact, disseminated, sand. Cleavage none; parting, sometimes distinct, six directions at 60°, 90°, 120° (110); brittle; fracture conchoidal, uneven.

Color red, brown, black, etc. (see varieties, p. 101). Streak white. Luster vitreous. Transparent to opaque. (See p. 244.) For varieties and occurrence, see p. 101.

92 DETERMINATIVE MINERALOGY [Sues. 15, 16

H.

G. 2.9-3.0 PHENACITE, Gl2SiO4.

8 Struct. — Hexagonal-rhombohedral crystals, prismatic, lenticular. Cleavage indistinct, three directions at 60° and 120° (1120); brittle; fracture conchoidal.

Color colorless, wine-yellow, rose-red, brown. Streak white. Luster vitreous. Transparent to translucent. (See p. 264.)

In pegmatite and metamorphic rocks with quartz, topaz, beryl, microcline, chrysoberyl.

9 G. 3.9-4.1 CORUNDUM (Adamantine Spar), A12O3.

Struct. — Rough hexagonal-rhombohedral crystals, prismatic, pyramidal, tabular, tapering (barrel-shaped), often striated; lamellar, granular, compact. Cleavage none; often conspicuous parting three directions at 86° and 94° (1011); sometimes transverse parting (0001); brittle, tough when compact; fracture uneven, conchoidal.

Color white, gray, brown to black; deep red (ruby); blue (sapphire); black from admixture of magnetite, hematite, or spinel (emery). Streak white. Luster vitreous, adamantine. Transparent to opaque. (See p. 260.)

In peridot ite, gneiss, schist, syenite, crystalline limestone; with olivine, chlorite, serpentine, magnetite, spinel, vermiculite; cyanite, diaspore, muscovite.

10 G. 3.5 DIAMOND (Carbon), C.

Struct. — Isometric crystals (octahedron, hexoctahedron, Figs. 1, 4) usually with curved surfaces; rounded and irregular grains, pebbles, often with radial structure. Cleavage distinct, four directions at 70|° and 109|° (111); brittle; fracture conchoidal.

Color white, colorless, pale shades of yellow, red, orange, green, blue, brown; occasionally black. Streak white. Luster adamantine, greasy. Transparent to opaque. (See p. 264.) For description of varieties, see p. 45.

In peridotite or serpentine; in sands, gravels quartzite; with pyrope, magnetite, chromite, zircon, gold,

Section 16

Streak chalk- white, colorless, or pale colored; mineral yellow, red, or brown; no distinct cleavage.

0 Kaolinite, Bauxite, Chalk, Tripolite, Gypsite.

1 Powdery, earthy, or clay-like minerals, which may be colored yellow, red, or brown by ferric oxides, although white when pure. (See pp. 30, 40, 46, 47.)

0 G. 4.5 Molybdite (Molybdic Ocher), MoO3 59.4%.

1£ Struct. — Earthy powder, crusts; rarely fibrous, radiating, or hair-like

orthorhombic crystals. Cleavage distinct, one direction crosswise (001);

brittle.

Sec. 16] Physical Tables 93

H.

Color and streak straw-yellow, yellowish white. Luster dull, silky. Translucent to opaque. (See p. 228.)

With molybdenite, of which it is an alteration product.

1 G. 5.5-5.6 CERARGYRITE (Horn Silver}, AgCl; Ag 75.3%; sometimes Hg. Struct. — Wax-like crusts, stalactitic, dendritic; isometric (cubic) crystals rare. Cleavage none; highly sectile; fracture conchoidal.

Color pearly gray, greenish, colorless; turns violet, brown to black on exposure to light. Streak white, grayish, shiny. Luster waxy, greasy, resinous. Transparent to translucent. (See p. 216.)

In veins with other silver minerals, calcite, barite, limonite.

1 G. 5.3-5.8 EMBOLITE, Ag 60-70%.

1£ Struct. — Compact, stalactitic, concretionary; isometric crystals rare. Cleavage none; sectile; fracture uneven.

Color yellow, grayish green, yellowish green, becoming darker on exposure. Streak white. Luster resinous, adamantine. Transparent to translucent. (See p. 216.)

In oxidized parts of silver veins with calcite, barite, limonite.

1 G. 1.6 CARNALLITE, KMgCl3-6H20; KC1 26.8%.

2 Struct. — Granular, compact; orthorhombic (pseudohexagonal) crystals rare. Cleavage indistinct; brittle; fracture conchoidal.

Color white, grayish, brownish, reddish. Streak white. Luster vitreous, greasy. Transparent to translucent. Bitter taste; absorbs moisture and liquefies in moist air. (See p. 224.)

With halite, kieserite, sylvite, boracite, anhydrite.

1 G. 0.9-1.0 OZOCERITE (Mineral Wax, Native Paraffin), CnH2n+2.

2 Struct. — Amorphous, compact, fibrous, lamellar; plastic; may be sticky. Color black, brownish black, brownish yellow, leek-green. Streak yellow-

ish brown, pale yellow. Luster waxy, greasy, submetallic. Translucent, sometimes greenish opalescence. Like wax; greasy feel. (See p. 212.)

Burns with bright smoky flame and odor of paraffin. In veins in sedimentary rocks.

1 G. 6.4-6.5 Calomel (Horn Quicksilver] , Hg2Cl2; Hg 84.9%.

2 Struct. — Coatings; small tetragonal crystals, tabular, pyramidal. Cleavage indistinct, two directions at 90° (100); fracture conchoidal; sectile.

Color white, gray, yellowish, brown. Streak white, gray, yellowish. Luster adamantine. Translucent to opaque. (See p. 212.) In veins with cinnabar and mercury.

1 G. 2.4-2.6 KAOLINITE (Kaolin, China Clay, Porcelain Clay"), 2% Struct. — Friable, clay-like, compact; minute scaly monoclinic crystals (pseudohexagonal or pseudorthorhombic) rare; brittle; fracture earthy.

Color white, gray, yellowish, reddish. Streak white. Luster dull, pearly. Opaque to translucent. Generally plastic when moist. (See p. 256.)

With quartz, feldspars; largely from decomposition of latter; chief constituent of most clay. For varieties see p. 47. (Compare Bauxite, p. 47.)

94 Determinative Mineralogy [Sec. 16

H.

1 G. 2.1-2.2 TRIPOLITE (Tripoli, Infusorial Earth, Diatomite, Diatomace- 3 ous Earth], SiO2-nH2O; the composition of opal.

Struct. — Amorphous, porous, earthy, chalk-like; particles scratch glass; harsh feel; not plastic when wet.

Color white, gray yellowish. Streak white. Luster dull. Opaque. (See p. 54.)

Associated with and in part mingled with clay, sand, peat.

G. 2.2-2.3 SODA NITER (Chile Saltpeter), NaNO3; N2O6 63.5%.

2 Struct. — Granular, crusts, efflorescences; rarely hexagonal-rhombohedral crystals, like calcite. Cleavage distinct, three directions at 73|° and 106° (lOll); brittle, somewhat sectile; fracture conchoidal.

Color white, colorless, grayish, yellowish, brownish. Streak white. Luster vitreous. Transparent to translucent. Taste cool, salty; becomes damp in moist air. (See p. 224.)

Extensive deposits in some arid districts (Chile); with gypsum, sand, clay, guano.

1£ G. 2.0-2.1 SULPHUR (Brimstone), S; traces of Te, Se, As. Struct. — Granular, fibrous, compact, earthy; reniform, stalactitic, incrusting; orthorhombic crystals, pyramidal (Figs. 34, 35 ), or tabular. Cleavage indistinct; very brittle; fracture conchoidal.

Color yellow, greenish or reddish yellow, brown, gray. Streak white, pale yellow. Luster resinous, greasy, adamantine. Transparent to translucent. (See p. 212.)

In beds with gypsum; about vents of volcanoes and fumaroles; in oxidized parts of sulphide ores; with celestite, gypsum, calcite, aragonite.

2 G. 1.9 MELANTERITE, (Copperas, Green Vitriol), FeSO4-7H2O.

Struct. — Capillary, fibrous, compact, stalactitic, concretionary, powdery; monoclinic crystals rare. Cleavage inconspicuous, one direction crosswise (001); brittle; fracture conchoidal, earthy.

Color green, yellowish green, white; dull yellowish white on exposure. Streak white. Luster vitreous, dull. Transparent to translucent. Sweet astringent taste. (See p. 218.)

Oxidation product of iron sulphide minerals — marcasite, pyrite, chalcopyrite, pyrrhotite, etc.

2 G. 1.0-2.0 SEPIOLITE (Meerschaum), H4Mg2Si3Oi0; sometimes Cu and Ni. Struct. — Compact, nodular, earthy, clay-like, rarely fibrous; floats when dry. Cleavage none; brittle; fracture conchoidal, uneven; smooth feel; adheres to tongue.

Color white, grayish, yellowish. Streak white. Luster dull. Opaque. (See pp. 232, 254.)

In peridotites and serpentine with magnesite, chlorite; masses in stratified earthy deposits.

2 G. 3.6-3.8 Hydrozincite (Zinc Bloom), Zn 60.8%. Struct. — Earthy, compact, fibrous, incrusting, stalactitic. Cleavage none; brittle; fracture uneven, splintery.

Sec. 16] Physical Tables 95

H.

Color white, gray, yellow. Streak white. Luster dull, pearly. Opaque. (See p. 248.)

With calamine, smithsonite, other secondary zinc minerals, sphalerite.

2 G. 2.6-2.7 Pharmacolite (Arsenic Bloom], HCaAsO4-2H2O. 2 Struct. — Fibrous, acicular, incrusting, powdery; small prismatic monoclinic crystals rare. Cleavage distinct, one direction lengthwise (010); sectile; thin flakes flexible; fracture uneven.

Color white, grayish; may be tinged red by Co or green by Ni. Streak white. Luster vitreous, pearly. Translucent to opaque. (See p. 228.) With arsenopyrite and arsenical ores of cobalt and silver.

21 G. 2.9-3.0 CRYOLITE, Na3AlF6; Na 32.8%; Al 12.8%.

Struct.: — Cleavable, granular, compact; rarely small monoclinic crystals, like cubes and octahedrons. Cleavage none; often parting three directions at 88°, 90°, and 92° (001) (110); brittle; fracture uneven.

Color white, colorless, brownish, reddish. Streak white. Luster vitreous, greasy; pearly on (001). Transparent to translucent. (See p. 226.)

Often resembles ice or paraffin. In veins with quartz, siderite, galena, sphalerite, pyrite, chalcopyrite, fluorite.

2 G. 2.0-2.2 DEWEYLITE (Gymnite) approx. variable.

3 Struct. — Amorphous, like gum or resin; brittle; often much cracked. Color yellow, white, greenish, reddish. Streak white. Luster greasy,

resinous. Translucent. (See pp. 232, 254.) In serpentine and crystalline limestone.

G. 5.8-6.0 Bromyrite (Bromargyrite) , AgBr; Ag 57.4%.

Struct. — Compact, incrusting, concretionary; isometric crystals rare. Cleavage none; sectile; fracture uneven.

Color bright yellow to amber-yellow, greenish; often grass-green or olivegreen externally; little altered on exposure. Streak pale yellow, greenish yellow. Luster resinous, adamantine. Transparent to translucent. (See p. 216.)

With cerargyrite, embolite, cerusite, calcite, in oxidized portions of silver ores.

2% G. 1.0-1.1 AMBER (Succinite, Retinite), 3 Struct. — Amorphous, irregular lumps, grains; fracture conchoidal; brittle; sometimes inclusions of insects, vegetable remains, liquids, minerals.

Color yellow, brownish yellow, brownish red, whitish. Streak white. Luster greasy, resinous. Transparent to translucent. Electrified by friction. (See p. 212.)

Fossil resin in clays, sands, coal beds, sedimentary rocks.

96 Determinative Mineralogy [Sec. 16

H.

3 G. 6.6-7.2 VANADINITE, Pb 73%; V2O5 19.4%; sometimes

P, As.

Struct. — Small hexagonal crystals (prisms, Fig. 49), sometimes hollow; fibrous, incrusting, compact, globular. Cleavage none; brittle; fracture uneven, conchoidal.

Color ruby-red, brown, yellow. Streak white, pale yellow. Luster greasy, resinous. Translucent to opaque. (See p. 214.)

In oxidized parts of lead ores; in gold and silver veins; with pyromorphite, wulfenite, galena.

3 G. 6.7-7.0 WULFENITE, PbMoO4; Pb 56.4%; sometimes Ca.

Struct. — Thin square tabular tetragonal crystals; sometimes acute pyramidal; granular. Cleavage indistinct; brittle; fracture conchoidal, uneven. -

Color yellow, orange, olive-green, brown, yellowish gray, whitish. Streak white. Luster adamantine, resinous. Transparent to translucent. (See p. 214.)

In oxidized parts of lead veins with galena, pyromorphite, vanadinite.

3 G. 1.8-1.9 ALLOPHANE, approx. Al2SiO5-5H20; variable.

Struct. — Amorphous, incrusting, stalactitic; fracture conchoidal, earthy; brittle.

Color sky-blue, green, yellow, brown, colorless. Streak white. Luster vitreous, waxy. Translucent. Resembles opal. (See p. 252.)

In fissures and cavities in copper and iron mines; cavities hi marls and limestones.

3 G. 6.4-6.6 CERUSITE (White Lead Ore}, PbC03; Pb 77.5%. 3 £ Struct. — Pseudohexagonal orthorhombic crystals, clusters, star-shaped groups; granular, fibrous, compact. Cleavage indistinct, brittle; fracture conchoidal.

Color white, gray, colorless; or yellow, brown, etc., from impurities. Streak white. Luster adamantine, greasy, silky. Transparent to translucent. (See p. 214.)

In oxidized parts of lead ores with lead, zinc, iron, and copper minerals.

3 G. 2.5-2.6 SERPENTINE, H4Mg3Si2O9; commonly Fe, sometimes Ni.

4 Struct. — Massive compact, fibrous (chrysotile, asbestos); lamellar (marmolite); columnar (picrolite); brittle; fibers flexible and tough; fracture conchoidal, splintery.

Color olive-green, blackish green, yellowish green, yellow; rarely white. Streak white. Luster greasy, waxy, silky. Translucent to opaque. (See pp. 232, 254.)

Common alteration product of olivine rocks (peridotites) ; in dolomitic limestone; with magnetite, talc, chromite, magnesite, corundum, platinum, diamond. Mixed with dolomite, calcite, or magnesite in a mottled or clouded green marble (verdantique, or ophicalcite) .

Sec. 16] Physical Tables 97

H.

3 G. 4.3-4.4 WITHERITE, BaCO3; BaO 77.7%.

4 Struct.— Compact, granular, radial fibrous, lamellar; pseudohexagonal orthorhombic crystals resembling quartz. Cleavage indistinct, brittle; fracture uneven.

Color white, grayish, yellowish. Streak white. Luster vitreous, greasy. Transparent to translucent. (See p. 226.) In veins with galena, barite, fluorite, calcite,

G. 6.5-7.1 PYROMORPHITE (Green Lead Ore), Pb 76.3%; 4 P2O5 15.7%.

Struct. — Small prismatic hexagonal crystals, often rounded, barrelshaped, sometimes hollow; incrusting, reniform, disseminated. Cleavage none; brittle; fracture conchoidal, uneven.

Color green, yellow, brown, white, gray. Streak pale yellow, greenish yellow, white. Luster resinous, greasy, adamantine. Translucent to opaque. (See p. 214.)

In oxidized parts of lead veins with galena, cerusite, mimetite, barite, limonite.

3£ G. 2.6-2.8 ALUNITE (Alum Stone), K2O 11.4%; 4 A12O3 37%.

Struct. — Compact, granular, fibrous, earthy; hexagonal-rhombohedral crystals, resembling cubes, rarely tabular. Cleavage indistinct, one direction (0001); brittle; fracture conchoidal, splintery, earthy.

Color white, grayish, reddish. Streak white. Luster vitreous, pearly. Transparent to opaque. (See pp. 248, 256.)

Veins and replacements in feldspathic rocks with quartz, kaolin, pyrite, opal.

3£ G. 2.3-2.4 WAVELLITE, P205 34.5%; sometimes F. 4 Struct. — Radial fibrous, globular with crystalline surface, stalactitic; distinct orthorhombic crystals rare. Cleavage three directions at 73°, 90°, and 107° (101) (010); brittle; fracture uneven, conchoidal.

Color green, yellow, white, brown. Streak white. Luster vitreous, pearly. Translucent. (See pp. 252, 256.)

In clays and in veins and joint cracks of rocks; with oxides of iron and manganese, pyrite, actinolite, amblygonite.

3£ G. 7.0-7.3 MIMETITE, Pb 69.5%; sometimes Ca and P. 4 Struct. — Prismatic, tabular, and barrel-shaped hexagonal crystals; globular, reniform, incrusting. Cleavage indistinct; brittle; fracture uneven.

Color yellow, orange, brown, colorless. Streak white. Luster greasy adamantine. Translucent. (See p. 214.)

In oxidized parts of lead ores with galena and pyromorphite.

3£ G. 3.1-3.3 SCORODITE, FeAsO4-2H2O.

4 Struct. — Pyramidal orthorhombic crystals, sometimes prismatic or tabular; botryoidal, fibrous, earthy, amorphous. Cleavage imperfect, two directions at 60° and 120° (120); brittle; fracture conchoidal, uneven.

98 Determinative Mineralogy [Sec. 16

H.

Color pale green, bluish green, blackish green, blue, brown. Streak white, grayish, greenish. Luster vitreous, greasy. Translucent. (See p. 218.)

With arsenopyrite, enargite, limonite, pyrite.

4£ G. 3.1-3.2 APATITE (Asparagus Stone), P2O5 42.3%; 5 often some Cl.

Struct. — Prismatic hexagonal crystals, sometimes tabular; granular, compact. Cleavage distinct to poor, one direction crosswise (0001); brittle; fracture conchoidal, uneven.

Color green, blue, violet, red, brown, white, colorless. Streak white. Luster vitreous, greasy. Transparent to opaque. (See pp. 228, 250.)

In crystalline limestones with graphite, fluorite, pyrrhotite; in igneous rocks (minute crystals); in magnetite ores; with fluorite in tin and tungsten ores; amorphous in stratified deposits with limestone and marl (phosphorite, phosphate rock, phosphatic nodules).

4£ G. 2.7-2.8 PECTOLITE, sometimes Mn. 5 Struct. — Fibrous, radiating, compact; rarely distinct monoclinic crystals. Cleavage two directions at 85° and 95° (100) (001); brittle; fracture splintery, uneven.

Color white, grayish, reddish. Streak white. Luster vitreous, silky. Translucent to opaque. (See p. 234.)

Amygdules and veins in igneous rocks, chiefly basic; in metalliferous veins; with zeolites, prehnite, datolite, native copper, calcite, quartz, epidote, pyrite, chalcopyrite, chlorite.

5 G. 4.3-4.5 SMITHSONITE (Dry Bone; Calamine, in England), ZnCO3; Zn52.1%.

Struct. — Mammillary, stalactitic, incrusting, cellular (dry bone); rarely small hexagonal-rhombohedral crystals with cleavage distinct, three directions at 72° and 108° (1011); brittle; fracture uneven, splintery.

Color white, grayish, colorless, greenish, blue, pink, brown. Streak white. Luster vitreous, adamantine, pearly, dull. Transparent to opaque. (See p. 248.)

In oxidized zinc ores, usually in limestone or clay, with calamine, cerusite, anglesite, galena, sphalerite, calcite, limonite.

5 G. 2.2-2.3 ANALCITE (Anakime, a zeolite), Struct. — Isometric crystals (trapezohedrons, Fig. 3); granular, compact. Cleavage none; brittle; fracture uneven, conchoidal.

Color white, colorless, grayish, greenish, yellowish, reddish. Streak white. Luster vitreous. Transparent to opaque. (See p. 232.)

Amygdules and veins in igneous rocks, chiefly basic (sometimes primary constituent of rock); metalliferous veins; with other zeolites, prehnite, datolite, pectolite, native copper, calcite, quartz, epidote, pyrite, chalcopyrite, chlorite.

Sec. 16] Physical Tables 99

H.

5 G. 2.9-3.0 Datolite,

5 1 Struct. — Complex monoclinic crystals; granular, compact, botryoidal (botryolite). Cleavage none; brittle; fracture conchoidal, uneven.

Color greenish, colorless, yellowish, reddish, grayish. Streak white. Luster vitreous, greasy, dull. Transparent to opaque. (See p. 230.)

Amygdules and veins in igneous rocks, chiefly basic; metalliferous veins; with zeolites, prehnite, pectolite, native copper, calcite, quartz, epidote pyrite, chalcopyrite, chlorite.

5 G. 2.3-2.4 THOMSONITE (a zeolite), Struct. — Radial fibrous, columnar, spherical concretions, compact; rarely distinct prismatic ortho rhombic crystals, striated lengthwise. Cleavage two directions lengthwise at 90° (100) (010); brittle; fracture uneven.

Color white, colorless, reddish, green, brown. Streak white. Luster vitreous, silky, pearly. Transparent to opaque. (See p. 230.)

Amygdules and veins in igneous rocks, chiefly basic; in metalliferous veins; with other zeolites, prehnite, datolite, pectolite, native copper, calcite, quartz, epidote, pyrite, chalcopyrite, chlorite.

5 G. 4.9-5.3 MONAZITE, also Th, Y; Th02 up to 10%+. 5-2 Struct. — Sands, disseminated grains; small monoclinic crystals rare. Cleavage indistinct; sometimes parting one direction (001); brittle; fracture conchoidal, uneven.

Color yellow, yellowish green, yellowish brown, reddish brown. Streak white. Luster resinous, vitreous-. Translucent to opaque. (See p. 256.) In pegmatite, gneiss; in sands of streams or seashore; with magnetite ilmenite, garnet, corundum, gold, platinum.

5 G. 2.1-2.3 SOD ALITE (a feldspathoid), 3.

6 Struct. — Compact, disseminated grains, nodular; isometric crystals (dodecahedrons) rare. Cleavage indistinct, six directions at 60°, 90°, and 120° (110); brittle; fracture conchoidal, uneven.

Color blue, gray, white, red, green. Streak white. Luster vitreous, greasy. Transparent to translucent. (See p. 230.)

In igneous rocks with nephelite, leucite, cancrinite; not with quartz.

5-J- G. 2.4-2.5 LEUCITE (Amphigene, a feldspathoid), K2O 21.5% 6 Struct. — Isometric crystals (trapezohedrons, Fig. 3); rounded disseminated grains. Cleavage indistinct; brittle; fracture conchoidal.

Color white, gray, yellowish, reddish, colorless. Streak white. Luster vitreous, greasy. Translucent to opaque. (See p. 254.)

In lavas with sanidine, augite, nephelite, olivine; not with quartz.

G. 3.9-4.1 Brookite (Arkansite), TiO2; Ti 60%.

6 Struct. — Orthorhombic crystals, often tabular (pseudohexagonal), also prismatic, faces often striated. Cleavage indistinct; brittle; fracture uneven.

100 Determinative Mineralogy [Sec. 16

H.

Color hair-brown, yellowish and reddish brown to iron-black. Streak white, grayish, yellowish, brownish. Luster adamantine, metallic. Opaque (See pp. 210, 262.)

In igneous rocks, gneiss, crystalline limestone; in veins with quartz feldspars, metallic sulphides; with rutile, octahedrite, titanite, adularia, nephelite; in gold placers.

5-| G. 4.3-5 .8 Fergusonite, some Ca, Fe, H2O. 6 Struct. — Disseminated, compact; pyramidal tetragonal crystals rare. Cleavage none; brittle; fracture conchoidal, uneven.

Color brownish black, brown. Streak pale brown. Luster submetallic, vitreous; often dull outside. Translucent to opaque. (See pp. 210, 264.)

Brilliant luster of fresh fracture in striking contrast with dull surface. In granite and pegmatite with quartz, feldspars, zircon, allanite, gadolinite; in placer gravels.

5£ G. 2.1-2.2 OPAL, SiO2-nH20; H20 2-16%, chiefly 3-9%. Si Struct. — Amorphous, botryoidal. reniform, stalactitic, earthy. Cleavage none; battle; fracture conchoidal, conspicuous when compact.

Color white, yellow, red, brown, green, gray, blue, colorless; sometimes a rich play of colors. Streak white. Luster vitreous, pearly, dull. Transparent to opaque. (See pp. 256, 260, 264.)

In cavities and veins in igneous and sedimentary rocks. For description of varieties, see p. 54.

6 G. 3.1-3.2 CHONDRODITE, some Fe replaces Mg. Struct. — Rounded disseminated grains, compact; small complex monoclinic crystals rare. Cleavage sometimes distinct, one direction (001); brittle; fracture conchoidal, uneven.

Color brownish red, yellow, white. Streak white. Luster vitreous, greasy. Translucent to opaque. (See p. 252.)

In crystalline limestone with spinel, magnetite, pyroxene, vesuvianite, phlogopite, corundum.

6 G. 4.1-4.3 RUTILE (Nigrine),TiOz; Ti 60%; often Fe.

7 Struct. — Prismatic tetragonal crystals, striated lengthwise; knee-shaped and rosette twins; acicular, compact, disseminated. Cleavage indistinct; brittle; fracture uneven.

Color red, reddish brown, black (deep red when transparent). Streak white, gray, pale brown. Luster metallic, adamantine. Transparent to opaque. (See pp. 210, 262.)

In veins with quartz, feldspars, hematite, ilmenite; hair-like inclusions in quartz; in igneous contacts and metamorphic rocks.

6 G. 6.8-7.1 CASSITERITE (Tinstone), SnO2; Sn 78.6%; sometimes Fe

7 and Ta.

Struct. — Granular, disseminated, reniform with radiating fibrous structure (wood tin)] sand and pebbles (stream tin)', thick prismatic tetragonal crystals, knee-shaped twins common (Fig. 29). Cleavage indistinct; brittle; fracture uneven.

Sec. 16] Physical Tables 101

H.

Color brown to black; rarely yellow, red, gray, white. Streak white, grayish, brownish. Luster adamantine, greasy, dull. Transparent to opaque. (See p. 262.)

In granite, gneiss, with wolframite, scheelite, molybdenite, tourmaline, fluorite, topaz, apatite, lepidolite; in pegmatites; in sands and gravels.

6 G. 4.0-4.5 Gadolinite, some Ce, La, Nd, Pr, Er, Sc, etc.

7 Struct. — Compact, disseminated, nodular; rough prismatic monoclinic crystals rare. Cleavage none; brittle; fracture conchoidal, splintery.

Color black, greenish black, brown; thin splinters grass-green tg olivegreen. Streak greenish gray. Luster vitreous, greasy. Translucent to opaque. (See pp. 232, 252.)

In granite and pegmatite with quartz, mica, allanite, fergusonite, fluorite, molybdenite.

G.3.3.-3.5 VESUVIANITE (Idocrase), often Mg,

Fe, Mn.

Struct. — Short prismatic tetragonal crystals (Figs. 27, 28); columnar, granular; compact, like jade (calif ornite) . Cleavage indistinct; brittle; fracture uneven.

Color brown or green, rarely yellow or blue. Streak white. Luster vitreous, greasy, resinous. Translucent to opaque. (See p. 244.)

In limestone contacts with garnet, pyroxene, tourmaline, chondrodite, wollastonite, epidote.

6£ G. 3.2-3.6 OLIVINE (Chrysolite, Peridot], ranging from 7 Forsterite, Mg2SiO4, to Fayalite, Fe2SiO4; sometimes a little

Ni, Sh, Ti.

Struct. — Granular, disseminated; prismatic or tabular orthorhombic crystals (Fig. 36) rare. Cleavage indistinct, two directions at 90° (100) (010); brittle; fracture conchoidal, uneven.

Color yellowish green, yellowish brown, reddish. Streak white, yellowish white. Luster vitreous. Transparent to translucent. (See p. 252.)

In basic igneous rocks (gabbro, basalt, peridotite) with augite, chromite, corundum, spinel, pyrope; rarely in crystalline dolomite.

6£ G. 3.4-4.3 GARNET, R" Ca, Mg, Fe, Mn; R'"=A1, 7 £ Fe, Cr, sometimes Ti.

Struct. — Isometric crystals (dodecahedrons, trapezohedrons, Figs. 3, 7, 8); granular, lamellar, compact, disseminated, sand. Cleavage none; parting sometimes distinct, six directions at 60°, 90°, 120° (110); brittle; fracture conchoidal, uneven.

Color red, brown, black, etc. (see varieties below). Streak white. Luster vitreous. Transparent to opaque. (See p. 244.)

Pyrope, deep red to reddish black, rarely purple; sp. g. 3.7. Rounded grains in peridotite and serpentine.

Almandite (almandine), deep red to brownish black; sp. g. 3.9-4.2. In schists and gneiss with mica, staurolite, andalusite, cyanite.

Spessaritite, brownish red to hyacinth-red; sp. g. 4.0-4.3

102 Determinative Mineralogy [Sec. 16

H.

In granite and pegmatite with topaz, tourmaline, quartz, orthoclase.

Grossularite (grossular, cinnamon stone, essonite, hessonite), white, yellow, green, pink; sp. g. 3.5-3.6. In limestone contacts with wollastonite, vesuvianite, diopside, scapolite.

Andradite, wine-red, greenish, yellow, brown, black (melanite); sp. g. 3.8-3.9. In phonolite, nephelinite, leucitophyre, and contacts, with magnetite, epidote, feldspar, nephelite, leucite.

Uvarovite, or emerald-green, small crystals; sp. g. 3.4-3.5. In peridotite, serpentine, with chromite, talc, chlorite.

fichorlomite, black, sometimes tarnished to peacock' tints; sp. g. 3.8-3.9; streak grayish black. Masses in nephelite syenite with brookite and crystals of other black garnets.

Much common garnet is a mixture of grossularite, almandite, and andradite.

7 G. 2.65 QUARTZ (Rock Crystal), Si02.

Struct. — Prismatic hexagonal crystals striated crosswise, commonly terminated by double rhombohedron (like hexagonal pyramid); granular, disseminated, compact. Cleavage indistinct; brittle; fracture conchoidal.

Color white, colorless, and various shades to black (see varieties, p. 55). Streak white. Luster vitreous, greasy. Transparent to opaque. (See p. 262.)

In igneous rocks, gneiss, schist, sand, sandstone, quartzite; common vein mineral with many metallic ores.

7 G. 2.6-2.64 CHALCEDONY (Agate, Flint, Hornstone, Jasper), SiO2.

Struct. — Compact, botryoidal, mammillary, banded. Cleavage none; brittle to tough; fracture conchoidal.

Color white, gray, yellow, red, brown, black (see varieties p. 55) . Streak white. Luster waxy, vitreous, to nearly dull. Translucent to opaque. (See p. 262.)

Lining or filling cavities (agate, etc.); concretions in chalk (flint) or in limestone (chert, hornstone).

7 G. 2.9-3.0 Boracite,

Struct. — Isometric-tetrahedral crystals (tetrahedron, cube), small, isolated; groups rare; granular. Cleavage indistinct; brittle; fracture conchoidal, uneven.

Color white, colorless, grayish, yellow, green. Streak white. Luster vitreous. Transparent to opaque. (See pp, 228, 242.)

Commonly disseminated glassy crystals with gypsum, anhydrite, halite, carnallite.

7 G. 3.0-3.2 TOURMALINE, R Mg,Fe,Ca,Na,K,Li.

7 £ Struct. — Prismatic hexagonal-rhombohedral crystals, hemimorphic, curved triangular in cross-section, striated lengthwise (Fig. 58) ; radiating, columnar, compact. Cleavage indistinct; brittle; fracture uneven, conchoidal.

Sec. 16] Physical Tables 103

H.

Color black (schorl], blue (indicolite) , pink to red (rubellite), brown, green; rarely white or colorless (achroite). Streak white. Luster vitreous, resinous. Transparent to opaque. (See pp. 222, 242, 258.)

In pegmatite, gneiss, mica schist, slate, gravels; common at contacts; with quartz, feldspars, beryl, topaz, cassiterite, fluorite.

7 G. 3.6-3.8 STAUROLITE (Staurotide) , some- 7 1 times Mg, Mn.

Struct. — Prismatic orthorhombic crystals; cross twins at 60° and 90° common (Figs. 31 to 33) ; often rough. Cleavage not conspicuous, one direction lengthwise (010); brittle; fracture conchoidal, uneven.

Color yellowish brown, reddish to brownish black, weathering gray. Streak white to grayish. Luster vitreous, dull. Translucent to opaque. (See p. 260.)

In slate, schists, gneiss, with garnet, cyanite, sillimanite, tourmaline.

7 G. 3.0 Danburite,

7 1 Struct. — Prismatic orthorhombic crystals, like topaz; disseminated. Cleavage indistinct; brittle; fracture uneven, conchoidal.

Color wine-yellow, yellowish white, yellowish brown. Streak white. Luster vitreous, greasy. Transparent to translucent. (See p. 242.)

With calcite, dolomite, mica, oligoclase, microcline, pyroxene, tourmaline.

G. 4.5-4.8 ZIRCON, ZrSiO4; ZrO 67.2%; commonly a little Fe.

Struct. — Square tetragonal crystals with prism and pyramid; irregular lumps, disseminated grains. Cleavage indistinct; brittle; fracture uneven.

Color gray, brown, yellow, green; red transparent (hyacinth); colorless or smoky (jargon). Streak white. Luster adamantine, vitreous. Opaque to transparent. (See p. 262.)

Minute grains in feldspathic igneous rocks; rare in crystalline limestone, gneiss, schist; with magnetite, apatite, biotite, wollastonite, titanite; in placers with gold, corundum, spinel, garnet, monazite.

G. 2.6-2.8 BERYL, a little H, sometimes Na, Li, Cs. Rare pink varieties (rose beryl, morganite). See p. 127.

G. 3.6-4.6 SPINEL, MgAl2O4; also Fe, Mn, Cr, Zn— see varieties. Struct. — Isometric crystals (octahedrons, Fig. 1); granular, compact, disseminated. Cleavage indistinct; brittle; fracture conchoidal.

Color red, yellow, green, blue, brown, black (see varieties, p. 127.) Streak white. Luster vitreous, dull. Transparent to opaque. (See p. 262.) For varieties, occurrence, and associations, see p. 127.

9 G. 3.9-4.1 CORUNDUM (Adamantine Spar), A12O3. Brown, pink, and ruby varieties. See p. 45.

104 Determinative Mineralogy [Sec. 17

Section 17

Streak chalk- white, colorless, or pale colored; mineral green, blue, or violet; distinct cleavage one direction only.

H.

1 G. 2.3-2.8 VERMICULITE (Jefferisite, Culsageeite, etc., "Cat Gold."

Hydrated micas and chlorites; silicates of Mg; Fe, Al.

Struct. — Scaly, flaky; monoclinic pseudomorphous crystals. Cleavage perfect, one direction (001); thin flakes flexible — some very slightly so; not elastic.

Color yellow, yellowish brown, brownish red, yellowish green, dark green. Streak white. Luster pearly to nearly dull, metallic. Translucent to opaque. (See p. 232.)

With peridotite, serpentine, talc, chlorite, corundum, micas.

1 G. 2.8-2.9 PYROPHYLLITE (Pencil St one),

2 Struct. — Foliated, granular, fibrous, radial, compact; indistinct orthorhombic crystals rare. Cleavage perfect, one direction (001) ; fracture uneven, splintery; thin flakes flexible, not elastic; feel greasy.

Color white, apple-green, gray, yellow. Streak white. Luster pearly to dull. Translucent to opaque. (See p. 256.)

In schistose rocks with cyanite, topaz, graphite, lazulite.

1 G. 2.5-2.8 TALC (Steatite, Soapstone, Potstone), 2% Struct. — Foliated, granular; fibrous (agolite); compact (soft, French chalk; waxy, rensselaerite) ; indistinct tabular monoclinic crystals rare. Cleavage perfect, one direction (001); sectile; fracture uneven; thin flakes flexible, not elastic; greasy feel.

Color apple-green, gray, white. Streak white. Luster pearly, greasy. Transparent to opaque. (See pp. 236, 246, 256.)

In crystalline schists with serpentine, dolomite, magnesite, chlorite, actinolite.

1 G. 2.6-3.0 CHLORITE (ClinocMare, Pennine, Prochlorite), H, Fe, Mg, Al 2 1 silicates.

Struct. — Foliated, scaly, granular, compact, earthy; tabular six-sided monoclinic crystals rare. Cleavage perfect, one direction (001); fracture scaly, earthy; thin flakes flexible, tough, not elastic; slight soapy feel.

Color light to dark green. Streak white, greenish white, grayish. Luster pearly, vitreous, dull. Translucent to opaque. (See pp. 236, 254.)

In schists, greenstones, green slates, serpentines, peridotites; with magnetite, chromite, garnet, talc, pyroxene, serpentine, corundum.

lj G. 2.6-2.7 VIVIANITE (Blue Iron Earth), P2O5 28.3%.

2 Struct. — Radial fibrous, earthy; prismatic and tabular monoclinic crystals. Cleavage distinct, one direction (010); sectile; thin flakes flexible; fracture splintery, earthy.

Sec. 17] Physical Tables 105

H.

Color blue, green, greenish black; colorless when fresh, turns blue on exposure to light or grinding in a mortar. Streak white, blue, greenish blue. Luster pearly on cleavage; vitreous, dull. Transparent to opaque. (See p. 104.)

In clay, marl, peat; in cavities of fossils; with limonite; in veins with pyrrhotite, pyrite, gold.

G. 2.1 COPIAPITE (Misy), 17H2O; often Al and Mg.

2 Struct. — Granular, scales, crusts, powder; six-sided tabular monoclinic crystals rare. Cleavage one direction (010); brittle; fracture uneven, scaly, earthy.

Color yellow to greenish and brownish yellow. Streak yellowish. Luster pearly, dull. Translucent to opaque. Disagreeable metallic taste. (See p. 218.)

With iron and copper sulphates from oxidation of sulphides.

2 G. 2.9-3.0 ROSCOELITE (Vanadium Mica}, approx.

V2O3 20-29%; some Mg, Fe. Struct. — Minute micaceous scales.

Color dark green to brown. Luster pearly. Translucent. (See p. 236.) In veins with quartz, gold, and tellurides; disseminated in sandstone with carnotite.

2 G. 2.3-2.4 BRUCITE, sometimes Fe and Mn. Struct. — Foliated, scaly, fibrous (nemalite) ; rarely broad tabular hexagonalrhombohedral crystals. Cleavage perfect, one direction (0001); sectile; thin flakes and fibers flexible.

Color white, grayish, bluish, greenish. Streak white. Luster pearly, on cleavage; vitreous, waxy. Transparent to translucent. (See pp. 248, 252.)

With serpentine, dolomite, magnesite, chromite.

2 G. 1.7 BORAX (Tinkal), Na2B4O7-10H2O; B2O3 36.6%.

2% Struct. — Compact, earthy, incrusting; short columnar monoclinic crystals. Cleavage distinct, one direction (100); brittle; fracture conchoidal.

Color white, colorless, grayish, bluish, greenish. Streak white. Luster vitreous, greasy. Translucent to opaque. Sweetish alkaline taste. (See pp. 226, 228.)

In mud of alkaline lakes and marshes with halite, gypsum, colemanite.

2 G. 2.7-3.0 MUSCOVITE (Common or White Mica, Potash Mica, Isinglass),

3 often a little Na, Ca, Mg, Fe, and F. Struct. — Foliated, flaky; fine scaly to fibrous (sericite, damourite); dense

(pinite)', rarely distinct monoclinic (pseudohexagonal) crystals. Cleavage perfect, one direction (001); thin flakes tough, very elastic.

Color white, gray, yellowish, greenish, brownish. Streak white. Luster vitreous, pearly. Transparent to translucent. (See p. 236.)

In pegmatite, granite, gneiss, schists, contacts; with feldspars, quartz, tourmaline, beryl, garnet.

106 Determinative Mineralogy [Sec. 17

H.

2 G. 2.8-3.1 BIOTITE (Black Mica, Ferromagnesian Mica),

3 a little F, often Ti.

Struct. — Plates, scales; pseudohexagonal monoclinic crystals rare. Cleavage conspicuous, one direction (001); thin flakes tough, very elastic, becoming more brittle with alteration.

Color black, brownish black, greenish black, dark green. Streak white. Luster pearly, submetallic. Transparent to opaque. (See pp. 204, 220, 236.)

Common in granite, syenite, gneiss, mica schist; less common in basic igneous rocks and contacts.

2 G. 2.8-2.9 PHLOGOPITE (Amber Mica, Bronze Mica, Magnesia Mica),

3 some F and Fe.

Struct. — Plates, scales; prismatic or tabular monoclinic crystals with hexagonal or orthorhombic outlines, commonly rough. Cleavage conspicuous, one direction (001); thin flakes tough, very elastic.

Color yellowish brown, brownish red, gray to green; rarely colorless. Streak white. Luster pearly, submetallic. Translucent to transparent. (See pp. 204, 236.)

Contacts in crystalline limestone; in serpentine; with pyroxene, amphibole, serpentine, graphite, apatite, corundum.

2 G. 2.8-2.9 LEPIDOLITE (Lithia Mica), Li2O

3 3.8-5.8%.

Struct. — Foliated, scaly, compact; rarely monoclinic crystals, small tabular or prismatic. Cleavage perfect, one direction (001) ; thin flakes tough, very elastic.

Color pink, lilac, yellowish, grayish white, white. Streak white. Luster pearly. Translucent. (See p. 236.)

In pegmatite with pink and green tourmaline, cassiterite, topaz, amblygonite, spodumene.

2 G . 2 .8-2 .9 Paragonite (Soda Mica) , H2NaAl 3 (SiO4) 3 .

3 Struct. — Fine scaly masses, compact; strong pearly luster. Otherwise like muscovite, above. In schists with cyanite, staurolite, tourmaline, garnet, actinolite. (See p. 236.)

2$ G. 6.2-6.5 Leadhillite,

Struct. — Tabular monoclinic (pseudohexagonal) crystals and twins; . compact, lamellar. Cleavage perfect, one direction (001); rather sectile; fracture conchoidal, rarely observable.

Color white, colorless, yellow, green, gray. Streak white. Luster pearly, adamantine. Transparent to translucent. (See p. 214.)

Twins and trillings like aragonite, but very heavy. Occurs sparingly with lead ores.

G. 2.3-2.4 GIBBSITE (Hydrargillite),

3 / Struct. — Stalactitic, botryoidal, fibrous or scaly aggregates; tabular

monoclinic (pseudohexagonal) crystals rare. Cleavage one direction (001),

seldom observable; tough.

Sec. 17] Physical Tables 107

H.

Color white, grayish, greenish, reddish. Streak white. Luster vitreous, pearly, dull. Translucent. (See p. 256.)

Chief constituent of some bauxite deposits; with corundum, natrolite, limonite.

3 G. 2.5-2.8 TALC (Steatite, Soapstone, Potstone),

4 Struct.— Foliated, granular; fibrous (agolite); compact (soft, French chalk; waxy, rensselaerite) ; indistinct tabular monoclinic crystals rare. Cleavage perfect, one direction (001); thin flakes flexible, not elastic; sectile: fracture uneven; greasy feel. Hardness commonly 1-2 £-.

Color apple-green, gray, white. Streak white. Luster pearly, greasy. Transparent to opaque. (See pp. 236, 246, 256.)

In crystalline schists; with serpentine, dolomite, magnesite, chlorite, actinolite.

G. 2.3-2.4 APOPHYLLITE a little F.

5 Struct. — Square tabular or cube-like tetragonal crystals; lamellar, granular, compact. Cleavage perfect, one direction (001); brittle; fracture uneven.

Color white, greenish, yellowish, reddish. Streak white. Luster vitreous; pearly on cleavage. Transparent to nearly opaque. (See p. 234.)

Amygdules and veins in igneous rocks, chiefly basic; in metalliferous veins; with zeolites, prehnite, datolite, pectolite, native copper, calcite, quartz, epidote, pyrite chalcopyrite, chlorite.

5 APATITE (p. 123), PYROXENE, DIOPSIDE (p. 111)."

5 G. 3.3-3.5 HYPERSTHENE (.a pyroxene), sometimes Al.

6 Struct. — Foliated, cleavable, granular; orthorhombic crystals rare. Cleavage perfect, one direction (010), less distinct two directions (110) at 46°, 88°, 92°, and 134°; brittle; fracture uneven.

Color grayish, greenish, and brownish black to bronze. Streak brownish gray, grayish white. Luster metalloidal bronzy, pearly. Opaque to translucent. (See pp. 222, 258.)

In basic igneous rocks with plagioclase feldspars, olivine, amphibole, pyroxene, magnetite, titanite; seldom with quartz.

6 G. 3.2-3.4 ZOISITE, often some Fe. Struct. — Columnar, bladed, fibrous, compact; prismatic orthorhombic crystals striated lengthwise, without terminations. Cleavage conspicuous, one direction lengthwise (010); brittle; fracture uneven,

Color gray, yellowish brown, greenish; also red (thulite). Streak white. Luster vitreous; pearly on cleavage. Transparent to opaque. (See p. 246.) In crystalline schists with hornblende, vesuvianite, cyanite, epidote, garnet, feldspars, quartz.

6 G. 3.2-3.5 EPIDOTE (Pistacite),

7 Struct. — Long monoclinic crystals striated lengthwise, commonly terminated by two sloping faces; columnar, divergent acicular, granular. Cleavage distinct, one direction lengthwise (001); brittle; fracture uneven.

108 DETERMINATIVE MINERALOGY [Sue. 17

H.

Color yellowish green to brown and black, gray, yellow, red. Streak white to grayish. Luster vitreous. Transparent to opaque. (See pp. 222, 246.)

In gneiss, schist, crystalline limestone, greenstone with garnet, magnetite, chlorite, native copper, zeolites.

6 G. 3.2-3.3 SILLIMANITE (FibroUte), Al2SiO5, or

7 Struct. — Fibrous, columnar, radiating; slender orthorhombic crystals without terminations. Cleavage one direction lengthwise (010); brittle; fracture splintery, uneven.

Color grayish white, hair-brown, greenish. Streak white. Luster vitreous, silky. Transparent to translucent. (See p. 260.)

In gneiss; in contacts of aluminous rocks with andalusite, cordierite, garnets, corundum.

6 G. 3.3-3.5 DIASPORE, A1O- OH; Al 45%; sometimes Fe.

7 Struct. — Scaly, bladed, fibrous; columnar and tabular orthorhombic crystals rare. Cleavage distinct, one direction (010); brittle; fracture conchoidal.

Color white, grayish, greenish, hair-brown, yellow, colorless. Streak white. Luster vitreous, pearly. Transparent to opaque. (See p. 260.) With corundum, emery, dolomite, margarite, chlorite, magnetite.

6 G. 3.3-3.4 AXINITE, sometimes Mn, Fe, Mg.

7 Struct. — Tabular wedge-shaped triclinic crystals (Fig. 45); lamellar, granular. Cleavage distinct, one direction (010) ; brittle; fracture conchoidal.

Color clove-brown, yellow, greenish, grayish blue, gray. Streak white. Luster vitreous. Transparent to translucent. (See p. 242.; In veins with quartz, feldspars, hornblende, chlorite.

6 G. 3.5-3.6 Chloriloid (Ottrelite), H2FeAl2SiO7; some Mg, sometimes Mn.

7 Struct. — Foliated, scaly, rosette groups; rarely tabular triclinic crystals, hexagonal in outline. (OUrelite, oblong scales.) Cleavage perfect, one direction (001); thin flakes brittle.

Color dark gray, greenish gray, greenish black. Streak white, grayish, pale green. Luster pearly, vitreous. Translucent to opaque. (See pp. 222, 258, 260.)

In hornfels, slate, schist, with chlorite, hornblende, garnet.

7 G. 2.6-2.7 CORDIERITE (lolite, Dichroite, Water Sapphire),

Struct. — Short six- or twelve-sided orthorhombic (pseudohexagonal) crystals; granular, compact, disseminated. Cleavage one direction lengthwise (010); parting sometimes conspicuous crosswise (001); brittle; fracture uneven, conchoidal.

Color light to dark smoky blue, gray, violet, yellow. Resembles blue quartz; often altering to dull green chlorite; transparent varieties show marked difference in color in different directions. Streak white. Luster vitreous, dull. Transparent to translucent. (See pp. 244, 260.)

Sec. 17, 18] Physical Tables 109

H.

In schists, gneiss, sometimes in granite; with quartz, feldspars, hornblende, tourmaline andalusite, sillimanite, garnet.

8 G. 3.4-3.6 TOPAZ, 2SiO4.

Struct. — Prismatic orthorhombic crystals, many striated lengthwise; granular, pebbles, compact. Cleavage perfect, one direction crosswise (001); brittle; fracture conchoidal, uneven.

Color white, colorless, yellow, pink, bluish, greenish. Streak white. Luster vitreous. Transparent to opaque. (See p. 260.)

Veins in pegmatite, rhyolite, granite; contacts; placers; with tourmaline, cassiterite, apatite, fluorite, beryl, garnet.

Section 18

Streak chalk- white, colorless, or pale colored; mineral green, blue, or violet; distinct cleavage two directions.

G. 3.7 STRONTIANITE (Strontian Spar), SrCO3; SrO 70.1%; some-

times Ca.

Struct. — Chisel- or spear-shaped orthorhombic crystals, pseudohexagonal prisms; columnar, acicular, fibrous, divergent; granular, compact. Cleavage distinct, two directions at 63° and 117° (110); brittle; fracture uneven.

Color white, colorless, grayish, greenish, yellowish. Streak white. Luster vitreous, greasy. Transparent to translucent. (See p. 246.)

In ore deposits with galena, barite, calcite, celestite, fluorite, pyrite; veins in limestone, chalk, marl.

4 G. 3.5-3.7 CYANITE (Kyanite, Disthene), Al2SiO5, or

5 Struct. — Long tabular or bladed triclinic crystals without terminations; may be curved or radiating. Cleavage pronounced, two directions lengthwise at 74° and 106° (100) (010); transverse parting (001) common; brittle; fracture splintery.

Color blue, white, gray, green nearly black; often streaked. Streak white. Luster vitreous. Transparent to translucent. (See pp. 256, 260.)

Hardness lengthwise 4-5, crosswise 6-7. In gneiss and mica schist with staurolite, garnet, corundum,

G. 3.4-3.5 CALAMINE (Electric Calamine, Hemimorphite), 5 Zn 54.2%.

Struct. — Tabular orthorhombic-hemimorphic crystals, commonly divergent cockscomb groups; mammillary, stalactitic, granular. Cleavage two directions lengthwise at 76° and 104° (110); brittle; fracture uneven, conchoidal .

110 Determinative Mineralogy [Sbc. 18

H.

Color white, colorless, yellowish, brownish, greenish, bluish. Streak white. Luster vitreous, adamantine dull. Transparent to translucent. (Seep. 252.)

In oxidized zinc ores, usually in limestone or clay, with smithsonite, cerusite, anglesite, galena, sphalerite, calcite, limonite.

5 G. 3.4-3.6 TITANITE (Spheric), CaSiTiO5; commonly a little Fe.

5% Struct. — Tabular or wedge-shaped monoclinic crystals; lamellar, compact. Cleavage distinct, two directions at 66| and 113£° (110); parting often distinct four directions at 54° and 126° (221); brittle; fracture conchoidal.

Color brown to black, yellow, gray, green; rarely rose-red. Streak white. Luster vitreous, resinous, adamantine. Transparent to opaque. (See pp. 234, 246.)

Accessory in many igneous rocks; in gneiss, chlorite schist, crystalline limestone; with chlorite, iron oxides, pyroxene, amphibole, zircon, apatite, quartz, feldspars, rutile.

5 G. 2.9-3.4 HORNBLENDE (an amphibole), with

6 A12O3 up to 15% or 20%, also ferric iron, alkalies (Na, K), and often H and F.

Struct. — Granular, columnar, fibrous, radiated; long prismatic monoclinic crystals, often rhombohedron-like terminations; prism angle 124°; some prisms short, six-sided. Cleavage perfect, two directions lengthwise at 56° and 124° (110); brittle; fracture uneven, splintery.

Color green, black, brown, gray. Streak brown, green, yellow, gray, white. Luster submetallic, vitreous, pearly, silky. Translucent to opaque. (See pp. 222, 238.)

Common in igneous and metamorphic rocks with feldspars, pyroxenes, chlorite, quartz, calcite.

5 G. 3.0-3.2 ACTINOLITE (an amphibole),

6 Struct. — Bladed or acicular monoclinic crystals; columnar, fibrous, divergent, granular, compact. Cleavage conspicuous, two directions lengthwise at 56° and 124° (110); brittle; fracture splintery, uneven.

Color bright to dark green, grayish green. Streak white. Luster vitreous, silky, pearly. Transparent to opaque. (See p. 238.)

In talc, chlorite, and hornblende schists and greenstones, with epidote, talc, serpentine.

5 G. 3.0-3.2 Anthophyllite (an amphibole), sometimes Al

6 (Gedrite).

Struct. — Lamellar, columnar, fibrous; prismatic orthorhombic crystals rare. Cleavage two directions lengthwise at 54|° and 125° (110); brittle; fracture splintery; fine fibers flexible (asbestos).

Color gray, clove-brown, greenish to emerald. Streak white. Luster vitreous, pearly, silky, sometimes metalloidal. Translucent to opaque. (See pp. 222, 238, 258.)

In schists with talc, hornblende, chlorite, mica.

Sue. 18] PHYSICAL TABLES 111

H.

5 G. 3.2-3.6 PYROXENE, ranging from Diopside,

6 to Hedenbergite, often some Al, Mn, and Na.

AUGITE (a pyroxene), like common pyroxene above, with Al2O3upto 15% or 20%; sometimes alkali metals, Na and K.

Struct. — Granular, columnar, rarely fibrous; lamellar (diallage) ; thick monoclinic prisms four- to eight-sided (Figs. 40, 41). Cleavage two directions lengthwise at 87° and 93° (110) sometimes distinct; parting often prominent crosswise (001); diallage has fine lamellar parting one direction lengthwise (100); brittle; fracture uneven.

Color bright to dark green, grayish green, black, brown. Streak greenish, brownish, grayish to white. Luster vitreous, submetallic, dull. Transparent to opaque. (See pp. 220, 222, 240.)

Common in basic igneous rocks; in crystalline limestones with garnet, chlorite, amphibole, wollastonite, magnetite, pyrite.

5 G. 3.2-3.6 DIOPSIDE (MalacoUle; a pyroxene), some Fe.

6 Struct. — Prismatic monoclinic (pseudotetragonal) crystals, stout, terminated (Figs. 40, 41); lamellar, granular, compact. Cleavage two directions lengthwise at 87° and 93° (110) sometimes distinct; often conspicuous transverse parting (001); brittle; fracture uneven.

Color white, colorless, grayish, green to black. Streak white, grayish to greenish. Luster vitreous, dull. Transparent to opaque. (See p. 240.)

In basic igneous rocks; in crystalline limestones with wernerite, vesuvianite, garnet.

5 G. 3.1-3.3 ENSTATITE (a pyroxene), FeO up to 12%.

6 Struct. — Lamellar, columnar, fibrous, compact; prismatic orthorhombic crystals rare. Cleavage distinct, two directions at 88° and 92° (110) ; parting one direction (010), bisecting cleavage angle; brittle; fracture uneven.

Color grayish white, yellowish, greenish, to olive-green and brown. Streak white. Luster vitreous, pearly; submetallic, bronzy (bronzite). Translucent to opaque. (See pp. 240, 258.)

In basic igneous rocks (gabbro, peridotite) and in serpentine.

5 G. 3.3-3.5 HYPERSTHENE (a pyroxene), sometimes Al.

6 Struct. — Foliated, cleavable, granular; orthorhombic crystals rare. Cleavage perfect, one direction (010), less distinct two directions (110) at 46°, 88°, 92°, and 134°; brittle; fracture uneven.

Color grayish, greenish, and brownish black to bronze. Streak brownish gray, grayish white. Luster metalloidal bronzy, pearly. Opaque to translucent. (See p. 222, 258.)

In basic igneous rocks with plagioclase feldspars, olivine, amphibole, pyroxene, magnetite, titanite; seldom with quartz.

G. 3.4-3.7 RHODONITE, MnSiO3; often Ca, Fe; sometimes Zn (Fow-

lerite).

Struct. — Granular, cleavable, compact; triclinic crystals,' tabular, commonly rough, with rounded edges. Cleavage distinct, two directions at 87£° and 92 (110); brittle, tough when compact; fracture conchoids!, uneven.

112 DETERMINATIVE MINERALOGY [Sec. 18

H.

Color brownish red, flesh-red, pink; sometimes yellowish or greenish; may tarnish brown or black on exposure. Streak white. Luster vitreous. Transparent to opaque. (See p. 240.)

In veins; in crystalline limestone with willemite, franklinite, zincite.

6 G. 3.0-3.1 AMBLYGONITE, Li2O 10.1%; often Na; sometimes

Oh.

Struct. — Cleavable, compact, columnar; triclinic crystals rare. Cleavage conspicuous, one direction (001), less distinct in another plane at 83° and 97° to this (100); brittle; fracture uneven.

Color white, pale gray, green, blue, yellow, brown. Streak white. Luster vitreous; pearly on (001). Translucent to opaque. (See p. 242.)

Resembles feldspars, but heavier. Rare in pegmatite with tourmaline, lepidolite, apatite, topaz.

6 G. 2.5-2.6 ORTHOCLASE (Potash Feldspar), KAlSi3O8; K2O 16.9%; 6£ often Na.

Struct. — Cleavable, granular, disseminated; prismatic and tabular monoclinic crystals and twins (Figs. 42 to 44). Cleavage distinct, two directions at 90° (010) (001); brittle; fracture conchoidal, uneven.

Color white, red, gray, green, colorless. Streak white. Luster vitreous; often pearly on cleavage. Transparent to opaque. (See p. 238.) For varieties, see p. 37.

In many igneous and metamorphic rocks; in veins and contacts; with quartz, other feldspars, mica, hornblende, pyroxene; in pegmatites with beryl, topaz, tourmaline.

6 G. 2.6-2.8 PLAGIOCLASE (Soda-lime and Lime-soda Feldspars), ranging from NaAlSi3O8 (ab) to CaAl2Si2O8 (an), generally also

some K.

Struct. — Lamellar, granular, disseminated; small triclinic crystals (Fig. 46). Cleavage distinct, two directions at 86°-86|° and 94°-93£° (001) (010); often striations on one cleavage; cleavage often curved; brittle; fracture uneven.

Color white, colorless, gray, green, bluish, reddish; sometimes play of colors — blue, green, yellow, red. Streak white. Luster vitreous, pearly. Transparent to opaque, sometimes opalescent. (See p. 238.) For description of varieties, see p. 37.)

In igneous rocks, gneisses, schists, with other feldspars, quartz, mica, chlorite, zeolites; sometimes in veins.

6 G. 3.0-3.1 Glaucophane (an amphibole), 65 Struct. — Columnar, fibrous, granular; prismatic monoclinic crystals, commonly indistinct. Cleavage distinct, two directions lengthwise at 58° and 122° (110); brittle, small fibers flexible; fracture uneven, conchoidal.

Color lavender-blue, azure-blue, bluish to grayish black. Streak white. Luster vitreous, pearly, silky. Translucent to opaque. (See p. 238.)

In schists and gneisses with mica, garnet, epidote, zoisite, amphiboles, pyroxenes.

Sec. 18] Physical Tables 113

H.

6 G. 3.5-3.6 Aegirite (Aegirine, Acmite] a pyroxene),

6 Struct. — Long prismatic monoclinic crystals with terminations blunt (aegirite) or sharp (acmite); acicular, fibrous. Cleavage distinct, two directions at 87° and 93° (110); brittle; fracture uneven.

Color greenish black to reddish and brownish black; acmite often green interior, brown exterior. Streak pale yellowish gray. Luster vitreous, resinous. Translucent to opaque. (See pp. 222, 240.)

In igneous rocks rich in soda and iron — aegirite granite, nephelite syenite, phonolite, pegmatite.

6 G. 3.5-3.7 CYANITE (Kyanite, Disthene), Al2Si06, or

7 Struct. — Long tabular or bladed triclinic crystals without terminations, may be curved or radiating. Cleavage pronounced, two directions lengthwise at 74° and 106° (100) (010); transverse parting (001) common; brittle; fracture splintery.

Color blue, white, gray, green, nearly black; often streaked. Streak white. Luster vitreous. Transparent to translucent. (See pp. 256, 260.)

Hardness lengthwise 4-5, crosswise 6-7. In gneiss and mica schist with staurolite, garnet, corundum.

6 G. 3.1-3.2 SPODUMENE (a pyroxene), Li208-4%; some Na.

7 Struct. — Cleavable, columnar, compact; rough prismatic or flattened monoclinic crystals, striated lengthwise. Cleavage conspicuous, two directions lengthwise at 87° and 93° (110); parting one direction, sometimes prominent, bisecting larger cleavage angle (100); brittle; fracture uneven, splintery.

Color white, gray, yellowish; emerald-green (hiddenite); pink to purple (kuneite). Streak white. Luster vitreous, pearly. Transparent to opaque. (See pp. 240, 242.)

In pegmatites with tourmaline, lepidolite, beryl, amblygonite, cassiterite.

G. 3.2-3.6 OLIVINE (Chrysolite, Peridot), ranging from 7 Forsterite, Mg2SiO4, to Fayalite, Fe2SiO4; sometimes a little

Ni, Sn, and Ti.

Struct. — Granular, disseminated; prismatic or tabular orthorhombic crystals (Fig. 36) rare. Cleavage indistinct, two directions at 90° (100) (010); brittle; fracture conchoidal, uneven.

Color yellowish green, yellowish brown, reddish. Streak white, yellowish white. Luster vitreous. Transparent to translucent. (See p. 252.)

In basic igneous rocks (gabbro, basalt, peridotite) with augite, chromite, corundum, spinel, pyrope; rarely in crystalline dolomite,

G. 3.1-3.2 ANDALUSITE (Chiastolite, Made), Al2SiO5, or

7 5 Struct. — Columnar, granular, disseminated; rough orthorhombic prisms, nearly square. Cleavage two directions at 89° and 91° (110); brittle; fracture uneven.

114 Determinative Mineralogy [Sec. 18, 19

H.

Color white, pink, reddish brown, olive-green; sometimes black and white cross or checkered pattern on cross-fracture (chiastolite, or made) . Streak white. Luster vitreous, dull. Translucent to opaque. (See p. 260.)

In slate, schists, and gneiss; with sillimanite, garnet, biotite, tourmaline, cordierite.

G. 3.1 Lawsonite,

8 Streak. — Prismatic or tabular orthorhombic crystals; lenticular plates. Cleavage perfect, two directions at 90° (010) (001); brittle; fracture uneven. Color pale blue, bluish gray, colorless; white or grayish spots due to alteration. Streak white. Luster vitreous, greasy. Transparent to opaque. (See p. 244.)

In schists with glaucophane, actinolite, margarite, epidote, garnet.

8£ G. 3.5-3.8 CHRYSOBERYL (Cymophane), G1A12O4.

Struct. — Tabular orthorhombic crystals, heart-shaped or pseudohexagonal twins, disseminated plates. Cleavage two directions at 60° and 120° (Oil); brittle; fracture uneven, conchoidal.

Color yellowish green, deep green, greenish white, greenish brown, yellow. Streak white. Luster vitreous, greasy. Transparent to translucent. (See p. 260.)

Alexandrite, the deep green variety, is red by gas or lamp light; cat's eye is yellowish green, opalescent.

In granite, gneiss, mica schist, placers; with beryl, garnet, tourmaline, sillimanite.

Section 19

Streak chalk-white, colorless, or pale colored; mineral green, blue, or violet; distinct cleavage three or more directions.

2 G. 2.1-2.6 HALITE (Common Salt, Rock Salt}, NaCl; Na 60.6%; often Ca, Mg.

Struct. — Granular, cleavable, compact; isometric crystals (cubes, Fig. 5). Cleavage distinct, three directions at 90° (100); brittle; fracture conchoidal. Color white, colorless, grayish, reddish, bluish. Streak white. Luster vitreous. Transparent to translucent. Taste salty. (See p. 224.)

Beds in sedimentary strata with gypsum, anhydrite, sylvite, calcite, clay, sand; in dry lakes; in brines.

2 G. 1.9-2.0 SYLVITE, KC1; K 52.4%; sometimes Na.

Struct. — Granular, compact; isometric crystals (cubes, Fig. 5). Cleavage distinct, three directions at 90° (100); brittle; fracture conchoidal.

Color white, colorless, grayish, bluish, reddish. Streak white. Luster vitreous. Transparent to translucent. Taste salty, bitter. Becomes damp in moist air. (See p. 224.)

In salt deposits; with halite, kainite, carnallite.

Sec. 19] Physical Tables 115

H.

2.}- G. 4.3-4.6 BARITE (Baryles, Heavy Spar}, BaSO4; sometimes Ca and Sr. 83 Struct. — Tabular and prismatic orthorhombic crystals, divergent groups; compact, lamellar, fibrous. Cleavage distinct, three directions at 78 2°, 90°, and lOlz0 (001) (110); brittle; fracture uneven.

Color white, colorless, light shades of yellow, brown, red, blue. Streak white. Luster vitreous, pearly. Transparent to opaque. (See p. 226.)

In veins with galena, sphalerite, fluorite, chalcopyrite; in limestones and residual clays with manganese and iron oxides.

3 G. 2.7 CALCITE (Cole Spar), CaCO3; often Mg, Fe, Mn, sometimes Pb.

Struct. — Hexagonal - rhombohedral crystals, prismatic, scalenohedral, rhombohedral, tabular, or acicular in habit (Figs. 52 to 57); rarely twins; cleavable, granular, stalactitic, oolitic, earthy. Cleavage perfect, three directions at 75° and 105° (lOll); fracture conchoidal, seldom observed; brittle.

Color white, colorless, pale shades of gray, yellow, red, green, blue, violet.; brown to black when impure. Streak white. Luster vitreous, dull. Transparent to opaque. (See p. 246.)

Chief constituent of limestone, marble, chalk, calcareous marl; in veins with metallic ores, quartz, pyrite, zeolites. For varieties see p. 40.

3. G. 6.1-6.4 ANGLESITE (Lead Vitriol), PbSO4; Pb 63.3%.

Struct. — Orthorhombic crystals; granular, compact. Cleavage inconspicuous, three directions at 76°, 90°, and 104° (001) (110); brittle; fracture conchoidal .

Color white, colorless, gray, brown, green. N Streak white. Luster adamantine, vitreous. Transparent to translucent. (See p. 214.)

In oxidized parts of ore deposits with lead, zinc, and iron minerals.

3 G. 3.9-4.0 CELESTITE, SrSO4; sometimes Ca and Ba.

Struct. — Tabular or prismatic orthorhombic crystals (Fig. 37); fibrous, cleavable, rarely granular. Cleavage distinct, three directions at 76°, 90°, and 104° (001) (110); brittle; fracture uneven.

Color white, colorless, bluish, reddish. Streak white. Luster vitreous, pearly. Transparent to translucent. (See p. 226.)

In limestones and shales with gypsum, halite, sulphur, galena, aragonite.

G. 2.8-2.9 DOLOMITE, sometimes Fe and Mn (much Fe, Ankerite) .

4 Struct. — Granular, cleavable, compact; hexagonal-rhombohedral crystals, faces often curved (pearl spar) . Cleavage perfect, three directions at 74° and 106° (lOll); brittle; fracture conchoidal, uneven.

Color white, colorless, gray, red, green, brown, black. Streak white. Luster vitreous, pearly. Transparent to opaque. (See p. 246.)

Extensive strata as dolomitic limestone and marble; gangue with ores of lead, zinc, etc.; with serpentine, talc, gyspum, and ordinary limestone.

G. 2.9-3.0 ARAGONITE (Flos Ferri), CaCO3; sometimes Sr and Pb.

4 Struct. — Chisel- or spear-shaped orthorhombic crystals, pseudohexagonal prisms; acicular, columnar, stalactitic, coral-like. Cleavage three directions at 64°, 90°, and 116° (110) (010); brittle; fracture conchoidal.

116 Determinative Mineralogy [Sec. 19

H.

Color white, gray, yellow, pale green, violet. Streak white. Luster vitreous, resinous. Transparent to translucent. (See p. 246.)

In beds of limonite, siderite, gypsum; in basalt, serpentine; with celestite, sulphur, metallic sulphides, zeolites; constitutes some shells (pearly layers of many), and coral.

G. 3.9-4.1 SPHALERITE (Blende, Zinc Blende, Jack, Black Jack, Rosin

4 Jack), ZnS; Zn 67%; may be replaced by Fe up to 18%.

Struct. — Cleavable masses, granular, compact, botryoidal; rounded

isometric-tetrahedral crystals. Cleavage pronounced, six directions at 60°,

90°, and 120° (110); brittle; fracture conchoidal.

Color yellow, brown, red, green, black; rarely white or pale gray (clewphane). Streak white, light to dark brown. Luster resinous, adamantine, submetallic. Transparent to opaque. (See pp. 200, 228, 250.)

Ore deposits and veins with galena, pyrite, chalcopyrite, fluorite, barite; also in limestones.

4 G. 3.0-3.2 FLUORITE (Fluor Spar, Blue John), CaF2; F 48.9%; sometimes Cl.

Struct. — Isometric crystals (cubes, Figs. 5, 12), penetration twins; cleavable masses, granular, columnar. Cleavage perfect, four directions at 70|° and 109|° (111); brittle; fracture uneven.

Color violet, blue, green, yellow, colorless, brown. Streak white. Luster vitreous. Transparent to translucent. (See p. 226.)

Common in veins and contacts with galena, sphalerite, calcite, barite, cassiterite, apatite, topaz, lepidolite; in limestones; rare in igneous rocks.

4 G. 3.5-3.7 CYANITE (Kyanite, Disthene), Al2SiO5, or

5 Struct. — Long tabular or bladed triclinic crystals without terminations; may be curved or radiating. Cleavage pronounced, two directions lengthwise at 74° and 106° (100) (010); transverse parting (001) common; brittle; fracture splintery.

Color blue, white, gray, green, nearly black; often streaked. Streak white. Luster vitreous. Transparent to translucent. (See pp. 256, 260.)

Hardness lengthwise 4-5, crosswise 6-7. In gneiss and mica schist with staurolite, garnet, corundum.

4i G. 5.9-6.2 SCHEELITE, CaWO4; WO3 80.6%; some Mo; sometimes Cu 5 (Cuproscheelite) .

Struct. — Small pyramidal tetragonal crystals resembling octahedrons, sometimes tabular; incrusting, granular, compact. Cleavage distinct, four directions at 80°, 110°, and 130|° (111); brittle; fracture conchoidal, uneven. Color white, yellow, brownish, greenish, reddish. Streak white to yellowish. Luster greasy, adamantine. Transparent to translucent. (See pp. 234, 254, 258.)

In veins and contacts with quartz, cassiterite, topaz, flourite, apatite, molybdenite.

Sec. 19] Physical Tables 117

H.

5 G. 4.3-4.5 SMITHSONITE (Dry Bone; Calamine, in England), ZnC03; Zn52.1%.

Struct. — Mammillary, stalactitic, in crusting; cellular (dry bone}; rarely small hexagonal-rhombohedral crystals with cleavage distinct three directions at 72° and 108° (lOll); brittle; fracture uneven, splintery.

Color white, grayish, colorless, greenish, blue pink, brown. Streak white. Luster vitreous, adamantine, pearly, dull. Transparent to opaque. (See p. 248.)

In oxidized zinc ores, usually in limestone or clay, with smithsonite cerusite, anglesite, galena, sphalerite, calcite, limonite.

5 G. 2.5-2.6 NEPHELITE (Nepheline, Elaeolite, a feldspathoid),NaA!SiO4;

6 also K (up to 7%K2O).

Struct. — Compact, disseminated grains; small hexagonal crystals rare. Cleavage distinct, three directions at 60° and 120° (10lO); brittle; fracture conchoidal, uneven.

Color reddish, brownish, greenish, gray, white, colorless. Streak white. Luster greasy, vitreous. Transparent to opaque. (See p. 232.)

In lavas and granular igneous rocks with feldspars, sodalite, cancrinite, biotite, zircon, corundum; not with quartz.

5 G. 2.4-2.5 CANCRINITE (a feldspathoid),

6 Struct. — Compact, lamellar, columnar, disseminated; prismatic hexagonal crystals rare. Cleavage distinct, three directions at 60° and 120° (10lO); brittle; fracture uneven.

Color white, gray, yellow, green, blue, reddish. Streak white. Luster vitreous, greasy, pearly. Transparent to translucent. (See p. 230.)

In granular igneous rocks with nephelite, sodalite, biotite, feldspars, titanite; not with quartz.

5 G. 2.6-2.8 WERNERITE (ScapolUe), n(

6 Struct. — Stout prismatic tetragonal crystals; compact, fibrous, granular. Cleavage three directions lengthwise at 45° and 90° (100) (110) not conspicuous; brittle; fracture conchoidal, uneven.

Color white, gray, greenish, bluish, reddish. Streak white. Luster vitreous, greasy. Translucent to opaque. (See pp. 234, 244.)

In crystalline limestones and schists with pyroxenes, amphiboles, apatite, garnet, biotite.

5 G. 3.9-4.2 WILLEMITE, Zn2SiO4; Zn 58%; may contain Mn (Troostite};

6 some Fe.

Struct. — Compact, granular, disseminated grains; prismatic hexagonalrhombohedral crystals rare. Cleavage distinct, three directions at 60° and 120° (1120); brittle; fracture conchoidal, uneven.

Color yellow, green, red, brown, white. Streak white. Luster vitreous. Transparent to opaque. (See pp. 232, 252.)

In crystalline limestone with franklinite, zincite, rhodonite,

118 Determinative Mineralogy [Sec. 19

H.

G. 3.8-3.9 Octahedrite (Anatase), TiO2; Ti 60%.

6 Struct. — Tetragonal crystals, pyramidal, tabular, rarely prismatic; Cleavage distinct, five directions at 82°, 111°, and 136|° (111) (001); brittle; fracture uneven.

Color brown, dark blue, black. Streak white, pale gray. Luster adamantine, metallic. Translucent to opaque. (See pp. 210, 262.)

Minute crystals in granular igneous rocks; in gneiss, schists, quartzite, limestone; with brookite, rutile, ilmenite, biotite, adularia, titanite, gold.

6 G. 3.5-3.7 CYANITE (Kyanite, Disthene), Al2SiO5, or

7 Struct. — Long tabular or bladed triclinic crystals without terminations, may be curved or radiating. Cleavage pronounced, two directions lengthwise at 74° and 106° (100) (010); transverse parting (001) common; brittle; fracture splintery.

Color blue, white, gray, green, nearly black; often streaked. Streak white. Luster vitreous. Transparent to translucent. (See pp. 256, 260.)

Hardness lengthwise 4-5, crosswise 6-7. In gneiss and mica schist with staurolite, garnet, corundum.

G. 3.4-4.3 GARNET, R" Ca, Mg, Fe, Mn; R'"=A1, 7 1 Fe, Cr, sometimes Ti.

Struct. — Isometric crystals (dodecahedrons, trapezohedrons, Figs. 3, 7, 8) ; granular, lamellar, compact, disseminated, sand. Cleavage none; parting sometimes distinct, six directions at 60°, 90°, 120° (110); brittle; fracture conchoidal, uneven.

Color red, brown, black, etc. (see varieties, p. 101). Streak white. Luster vitreous. Transparent to opaque. (See p. 244.)

9 G. 3.9-4.1 CORUNDUM (Adamantine Spar), A12O3.

Struct. — Rough hexagonal-rhombohedral crystals, prismatic, pyramidal, tabular, tapering (barrel-shaped), often striated; lamellar, granular, compact. Cleavage none; often conspicuous parting three directions at 86° and 940 (lOll); sometimes transverse parting (0001); brittle; tough when compact; fracture uneven, conchoidal.

Color white, gray, brown to black; deep red (ruby)', blue (sapphire)', black from admixture of magnetite, hematite, or spinel (emery). Streak white. Luster vitreous, adamantine. Transparent to opaque. (See p. 260.)

In peridotite, gneiss, schist, syenite, crystalline limestone; with olivine, chlorite, serpentine, magnetite, spinel, vermiculite; cyanite, diaspore, muscovite.

10 G. 3.5 DIAMOND (Carbon), C.

Struct. — Isometric crystals (octahedron, hexoctahedron, Figs. 1, 4), usually with curved surfaces; rounded and irregular grains, pebbles, often with radial structure. Cleavage distinct, four directions at 701° and (111); brittle; fracture conchoidal.

Sec. 19, 20] Physical Tables 119

H.

Color white, colorless; pale shades of yellow, red, orange, green, blue, brown; occasionally black. Streak white. Luster adamantine, greasy. Transparent to opaque. (See p 264.)

Bort, grayish to black, rough rounded masses with radial or confused crystalline structure, without distinct cleavage; sp. g. 3.5.

, Carbonado, or black diamond, granular to compact, without cleavage; sp. g. 3.1-3.3.

In peridotite or serpentine; in sands, gravels, quartzite; with pyrope, magnetite, chromite, zircon, gold.

Section 20

Streak chalk-white, colorless, or pale colored; mineral green, blue, or violet; no distinct cleavage.

1 G. 5.5-5.6 CERARGYRITE (Horn Silver), AgCl; Ag75.3%; sometimes Hg. 1£ Struct. — Wax-like crusts, stalactitic, dendritic; isometric (cubic) crystal? rare. Cleavage none; highly sectile; fracture conchoidal.

Color pearly gray, greenish, colorless; turns violet, brown to black on exposure to light. Streak white, grayish, shiny. Luster waxy, greasy, resinous. Transparent to translucent. (See p. 216.)

In veins with other silver minerals, calcite, barite, limonite.

1 G. 5.3-5.8 EMBOLITE, Ag 60-70%.

Struct. — Compact, stalactitic, concretionary; isometric crystals rare. Cleavage none; sectile; fracture uneven.

Color yellow, grayish green, yellowish green, becoming darker on exposure. Streak white. Luster resinous, adamantine. Transparent to translucent. (See p. 216.)

In oxidized parts of silver veins with calcite, barite, limonite.

1 G . 2 .2-2 .4 GLAUCONITE (Greensand, Green Earth) , approx . KFe H20 ;

2 K2O6-9%; some Al and Mg.

Struct. — Granular, earthy, disseminated; amorphous. Cleavage none; brittle; fracture earthy, uneven.

Color yellowish green, grayish green, blackish green. Streak light green, greenish white. Luster vitreous, dull. Opaque. (See p. 220.)

Abundant in greensand beds (so-called marls); disseminated in sands, clays, sandstones, limestones.

1 G. 0.9-1.0 OZOCERITE (Mineral Wax, Native Paraffin), CnH2n+2.

2 Struct. — Amorphous, compact, fibrous, lamellar; plastic, may be sticky. Color black, brownish black, brownish yellow, leek-green. Streak yellowish brown, pale yellow. Luster waxy, greasy, submetallic. Translucent, sometimes greenish opalescence. Like wax; greasy feel. (See p. 212.)

Burns with bright smoky flame and odor of paraffin. In veins in sedimentary rocks.

120 Determinative Mineralogy [Sec. 20

H.

1 G. 3.0-3.1 ANNABERGITE (Nickel Bloom, Nickel Ocher, Nickel Green),

2% Ni 29.4%; sometimes Co and Ca.

Struct. — Earthy, incrusting, compact, stains; capillary monoclinic crystals rare. Cleavage none; brittle; fracture uneven.

Color apple-green, light green. Streak pale green, greenish white. Luster dull, vitreous. Opaque to translucent. (See p. 218.)

Oxidation product of nickel arsenides; with smaltite. niccolite, chloanthite, calcite.

1 G. 2.3-2.8 GAENIERITE ( Noumeite, Genthite), approx. nH2O ; 2% Ni 8-35%.

Struct. — Compact, botryoidal, incrusting, earthy. Cleavage none; fracture conchoidal, earthy; brittle. Sometimes greasy feel. Hardness sometimes 3~4.

Color pale yellowish green to emerald-green. Streak white, greenish white. Luster greasy, resinous, dull. Opaque. (See pp. 254, 258.)

Veins in peridotites, serpentine; with chromite, talc, chlorite.

1£ G. 2.0-2.1 SULPHUR (Brimstone), S; traces of Te, Se, As. 2 1 Struct. — Granular, fibrous, compact, earthy; reniform, stalactitic, incrusting; orthorhombic crystals, pyramidal (Figs. 34, 35) or tabular. Cleavage indistinct; brittle; fracture conchoidal.

Color yellow, greenish or reddish yellow, brown, gray. Streak white, pale yellow. Luster resinous, greasy, adamantine. Transparent to translucent. (See p. 212.)

In beds with gypsum; about vents of volcanoes and fumaroles; in oxidized parts of sulphide ores; with celestite, gypsum, calcite, aragonite.

2 G. 1.9 MELANTERITE (Copperas, Green Vitriol), FeSO4-7H2O.

Struct. — Capillary, fibrous, compact, stalactitic, concretionary, powdery; monoclinic crystals rare. Cleavage inconspicuous, one direction crosswise (001); brittle; fracture conchoidal, earthy.

Color green, yellowish green, white; dull yellowish white on exposure. Streak white. Luster vitreous, dull. Transparent to translucent. Sweet astringent taste. (See p. 218.)

Oxidation product of iron sulphide minerals — marcasite, pyrite, chalcopyrite, pyrrhotite, etc.

2 G. 2.6-2.7 Pharmacolite (Arsenic Bloom), HCaAs04-2H2O. 2 Struct. — Fibrous, acicular, incrusting, powdery; small prismatic monoclinic crystals rare. Cleavage distinct, one direction lengthwise (010): sectile; thin flakes flexible; fracture uneven.

Color white, grayish; may be tinged red by Co or green by Ni. Streak white. Luster vitreous, pearly. Translucent to opaque. (See p. 228.) With arsenopyrite and arsenical ores of cobalt and silver.

2 G. 2.0-2.2 CHRYSOCOLLA, approx. CuSi03-2H2O; variable; Cu 20-50%.

3 Struct. — Amorphous, compact, reniform, incrusting, stains, earthy. Cleavage none; brittle; fracture conchoidal.

Sec. 20] Physical Tables 121

H.

Color green, greenish blue, blue; brown to black from impurities. Streak white to pale blue or green. Luster vitreous, greasy, dull. Translucent to opaque. (See p. 254.)

In oxidized parts of copper deposits, with malachite, azurite, cuprite, native copper.

2 G. 2.0-2.2 DEWEYLITE (Gmm7e), approx. variable.

3 Struct. — Amorphous, like gum or resin; brittle; often much cracked. Color yellow, white, greenish, reddish. Streak white. Luster greasy,

resinous. Translucent. (See pp. 232, 254.) In serpentine and crystalline limestone.

2 G. 5.8-6.0 Bromyrite (Bromargyriie) , AgBr; Ag 57.4%.

3 Struct. — Compact, incrusting, concretionary; isometric crystals rare. Cleavage none; sectile; fracture uneven.

Color bright yellow to amber-yellow, greenish; often grass-green or olivegreen externally; little altered on exposure. Streak pale yellow, greenish yellow. Luster resinous, adamantine. Transparent to translucent. (See p. 216.)

With cerargyrite, embolite, cerusite, calcite, in oxidized portions of silver ores.

2% G. 2.1-2.3 CHALCANTHITE (Blue Vitriol, Copper Vitriol, Bluestone),

CuSO4-5H2O; Cu 25.4%.

Struct. — Crystalline crusts, reniform, stalactitic, fibrous, powdery; small tabular triclinic crystals rare. Cleavage indistinct; brittle; fracture conchoidal, earthy.

Color deep blue, sky-blue, greenish blue. Streak white. Luster vitreous, dull. Translucent. Plates wet iron with copper by contact. Nauseous metallic taste. (See p. 216.)

In oxidized parts of copper veins; often deposited by mine waters.

3 G. 6.7-7.0 WULFENITE, PbMoO4; Pb 56.4%; sometimes Ca.

Struct. — Thin square tabular tetragonal crystals, sometimes acute pyramidal; granular. Cleavage indistinct; brittle; fracture conchoidal. uneven.

Color yellow, orange, olive-green, brown, yellowish gray, whitish. Streak white. Luster adamantine, resinous. Transparent to translucent. (See p. 214.)

In oxidized parts of lead veins with galena, pyromorphite, vanadinite.

3 G. 1.8-1.9 ALLOPHANE, approx. Al2SiO5-5H2O; variable.

Struct. — Amorphous, incrusting, stalactitic; brittle; fracture conchoidal, earthy.

Color sky-blue, green, yellow, brown, colorless. Streak white. Luster vitreous, waxy. Translucent. (See p. 252.)

Resembles opal. In fissures and cavities in copper and iron mines; cavities in marls and limestones.

122 Determinative Mineralogy [Sec. 20

H.

3 G. 2.5-2.6 SERPENTINE, H4Mg3Si2O9; commonly Fe, sometimes Ni.

4 Struct. — Massive compact; fibrous (chrysotile, asbestos); lamellar (marmolile)] columnar (picrolite); brittle; fibers flexible and tough. Cleavage none; fracture conchoidal, splintery.

Color olive-green, blackish green, yellowish green, yellow; rarely white. Streak white. Luster greasy, waxy, silky. Translucent to opaque. (See pp. 232, 254.)

Common alteration product of olivine rocks (peridotites) ; in dolomitic limestone; with magnesite, talc, chromite, magnetite, corundum, platinum, diamond. Mixed with dolomite, calcite, or magnesite in a mottled or clouded green marble (verdantique, or ophicalcite).

3 G. 2.3-2.8 GARNIERITE (Noumeite, Genthite), approx.

4 Ni 8-35%.

Struct. — Compact, botryoidal, incrusting, earthy. Cleavage none; fracture conchoidal, earthy; brittle. Sometimes greasy feel. Hardness sometimes l-2i

Color pale yellowish green to emerald-green. Streak white, greenish white. Luster greasy, resinous, dull. Opaque. (See pp. 254, 258.)

Veins in peridotites, serpentine; with chromite, talc, chlorite.

G. 6.5-7.1 PYROMORPHITE (Green Lead Ore), Pb 76.3%; 4 P205 15.7%.

Struct. — Small prismatic hexagonal crystals, often rounded, barrelshaped, sometimes hollow; incrusting, reniform, disseminated. Cleavage none; brittle; fracture conchoidal, uneven.

Color green, yellow, brown, white, gray. Streak pale yellow, greenish yellow, white. Luster resinous, greasy, adamantine. Translucent to opaque. (See p. 214.)

In oxidized parts of lead veins with galena, cerusite, mimetite, barite, limonite.

3£ G. 2.3-2.4 WAVELLITE, P2O5 34 -5%; sometimes F. 4 Struct. — Radial fibrous, globular with crystalline surface, stalactitic; distinct orthorhombic crystals rare. Cleavage three directions at 73°, 90°, and 107° (101) (010); brittle; fracture uneven, conchoidal.

Color green, yellow, white, brown. Streak white. Luster vitreous, pearly. Translucent. (See pp. 252, 256.)

In clays and in veins and joint cracks of rocks; with oxides of iron and manganese, pyrite, actinolite, amblygonite.

G. 3.1-3.3 SCORODITE, FeAsO4-2H2O.

4 Struct. — Pyramidal orthorhombic crystals, sometimes prismatic or tabular; botryoidal, fibrous, earthy, amorphous. Cleavage imperfect, two directions at 60° and 120° (120); brittle; fracture conchoidal, uneven.

Color pale green, bluish green, blackish green, blue, brown. Streak white, grayish, greenish. Luster vitreous, greasy. Translucent. (See p. 218.) With arsenopyrite, enargite, limonite, pyrite.

Sec. 20] Physical Tables 123

H.

4J G. 3.1-3.2 APATITE (Asparagus Stone}, P2O6 42.3%; often 5 some Cl.

Struct. — Prismatic hexagonal crystals, sometimes tabular; granular, compact. Cleavage distinct to poor, one direction crosswise (0001); brittle; fracture conchoidal, uneven.

Color green, blue, violet, red, brown, white, colorless. Streak white. Luster vitreous, greasy. Transparent to opaque. (See pp. 228, 250.)

In crystalline limestones with graphite, fluorite, pyrrhotite; in igneous rocks (minute crystals); in magnetite ores; with fluorite in tin and tungsten ores; amorphous in stratified deposits with limestone and marl (phosphorite, phosphate rock, phosphatic nodules).

5 G. 4.3-4.5 SMITHSONITE (Dry Bone; Calamine, in England), ZnCO3; Zn 52.1%.

Struct. — Mammillary, stalactitic, incrusting; cellular (dry bone)', rarely small hexagonal-rhombohedral crystals with cleavage distinct three directions at 72° and 108° (lOll); brittle; fracture uneven, splintery.

Color white, grayish, colorless, greenish, blue, pink, brown. Streak white. Luster vitreous, adamantine, pearly, dull. Transparent to opaque. (See p. 248.)

In oxidized zinc ores, usually in limestone or clay, with smithsonite, cerusite, anglesite, galena, sphalerite, calcite, limonite.

5 G. 2.9-3.0 Datolite,

5f Struct. — Complex monoclinic crystals; granular, compact, botryoidal (botryolite). Cleavage none; brittle; fracture conchoidal, uneven

Color greenish, colorless, yellowish, reddish, grayish. Streak white. Luster vitreous, greasy, dull. Transparent to opaque. (See p. 230.)

Amygdules and veins in igneous rocks, chiefly basic; metalliferous veins; with aeolites, prehnite, pectolite, native copper, calcite, quartz, epidote, pyrite, chalcopyrite, chlorite.

5 G. 2.2-2.3 ANALCITE (Anakime, a zeolite), Struct. — Isometric crystals (trapezohedrons, Fig. 3); granular, compact. Cleavage none; brittle; fracture uneven, conchoidal.

Color white, colorless, grayish, greenish, yellowish, reddish. Streak white. Luster vitreous. Transparent to opaque. (See p. 232.)

Amygdules and veins in igneous rocks, chiefly basic (sometimes primary constituent of rock); metalliferous veins; with other zeolites, prehnite, datolite, pectolite, native copper, calcite, quartz, epidote, pyrite, chalcopyrite, chlorite.

5 G. 2.3-2.4 THOMSONITE (a zeolite),

Struct. — Radial fibrous, columnar, spherical concretions, compact; rarely distinct prismatic orthorhombic crystals, striated lengthwise. Cleavage two directions lengthwise at 90° (100) (010) ; brittle; fracture uneven.

Color white, colorless, reddish, green, brown. Streak white. Luster yitreous, silky, pearly. Transparent to opaque. (See p. 230.)

124 Determinative Mineralogy [Sec. 20

H.

Amygdules and veins in igneous rocks, chiefly basic; in metalliferous veins; with other zeolites, prehnite, datolite, pectolite, native copper, calcite, quartz, epidote, pyrite, chalcopyrite, chlorite.

5 G. 4.9-5.3 MONAZITE, also Th, Y; Th02 up to 10%+. Struct. — Sands, disseminated grains; small monoclinic crystals rare. Cleavage indistinct; sometimes parting one direction (001); brittle; fracture conchoidal, uneven.

Color yellow, yellowish green, yellowish brown, reddish brown. Streak white. Luster resinous, vitreous. Translucent to opaque. (See p. 256.)

In pegmatite, gneiss; in sands of streams or seashore; with magnetite, ilmenite, garnet, corundum, gold, platinum.

5 G. 2.1-2.3 SODALITE (a feldspathoid),

6 Struct. — Compact, disseminated grains, nodular; isometric crystal (dodecahedrons) rare. Cleavage indistinct, six directions at 60°, 90°, and 120° (110); brittle; fracture conchoidal, uneven.

Color blue, gray, white, red, green. Streak white. Luster vitreous, greasy. Transparent to translucent. (See p. 230.)

In igneous rocks with nephelite, leucite, cancrinite; not with quartz.

5 G. 3.0-3.1 Lazulite (Blue Spar}, P2O5 45.4%.

6 Struct. — Acute pyramidal or tabular monoclinic crystals; granular, compact. Cleavage indistinct; brittle; fracture uneven.

Color sky-blue, pale greenish blue. Streak white. Luster vitreous. Translucent to opaque. (See p. 256.)

In veins and metamorphic rocks with siderite, corundum, cyanite, rutile.

5£ G. 2.6-2.8 TURQUOIS (Turkis, Turkish Stone), with 6 1.5-6.5% Cu.

Struct. — Compact, reniform, stalactitic, incrusting, thin seams, disseminated; triclinic crystals rare. Cleavage none; brittle; fracture conchoidal.

Color sky-blue, bluish green, apple-green. Streak white, pale green. Luster waxy, dull. Opaque to translucent. (See pp. 250, 256, 260.) Veins and seams in partly decomposed igneous rocks.

G. 2.1-2.2 OPAL, Si02-nH20; H20 2-16%; chiefly 3-9%. 6j Struct. — Amorphous, botryoidal, reniform, stalactitic, earthy. Cleavage none; brittle; fracture conchoidal, conspicuous when compact.

Color white, yellow, red, brown, green, gray, blue, colorless; sometimes a rich play of colors. Streak white. Luster vitreous, pearly, dull. Transparent to opaque. (See pp. 256, 260, 264.)

In cavities and veins in igneous and sedimentary rocks. For varieties, see p. 54.

Sec. 20] Physical Tables 125

H.

5-1 G. 3.0-3.3 JADE, (Jadeitc), or (Nephrite). Struct. — Very tough, compact; varieties of the amphiboles, tremolite and actinolite (nephrite) or of the pyroxene jadeite. Cleavage none; fracture splintery.

Color greenish, grayish, white. Streak white. Luster vitreous, waxy, dull. Translucent to opaque. (See pp. 238, 240.)

Rolled pebbles in clay; ancient or oriental utensils and art objects. Compare californite, a jade-like compact vesuvianite, below.

6 G. 2.8-3.0 PREHNITE, often some Fe. Struct. — Botryoidal, stalactitic, radial fibrous; rounded groups of tabular orthorhombic crystals; distinct crystals rare. Cleavage indistinct, one direction (001); brittle; fracture uneven.

Color light green, oil-green, gray, white; often fading on exposure. Streak white. Luster vitreous, waxy. Transparent to translucent. (See pp. 234, 244.) With zeolites, datolite, apophyllite, pectolite, native copper, calcite, quartz, epidote, chlorite — in igneous rocks, chiefly basic. '

G. 3.3-3.5 VESUVIANITE (Idocrase), often Mg,

Fe, Mn.

Struct. — Short prismatic tetragonal crystals (Figs. 27, 28); columnar, granular, compact, like jade (californite). Cleavage indistinct; brittle; fracture uneven.

Color brown or green, rarely yellow or blue. Streak white. Luster vitreous, greasy, resinous. Translucent to opaque. (See p. 244.)

In limestone contacts with garnet, pyroxene, tourmaline, chondrodite, wollastonite, epidote.

6 G. 4.0-4.5 Gadolinite, some Ce, La, Nd, Pr, Er, Sc, etc.

7 Struct. — Compact, disseminated, nodular; rough prismatic monoclinic crystals rare. Cleavage none; brittle; fracture conchoidal, splintery.

Color black, greenish black, brown; thin splinters grass-green to olivegreen. Streak greenish gray. Luster vitreous, greasy. Translucent to opaque. (See pp. 232, 252*)

In granite and pegmatite with quartz, mica, allanite, fergusonite, fluorite, molybdenite.

6£ G. 3.2-3.6 OLIVINE (Chrysolite, Peridot), ranging from 7 For sterile, Mg2SiO4, to Fayalite, Fe2SiO4; sometimes a little

Ni, Sn, and Ti.

Struct. — Granular, disseminated; prismatic or tabular orthorhombic crystals (Fig. 36) rare. Cleavage indistinct, two directions at 90° (100) (010); brittle; fracture conchoidal, uneven.

Color yellowish green, yellowish brown, reddish. Streak white, yellowish white. Luster vitreous. Transparent to translucent. (See p. 252.)

In basic igneous rocks (gabbro, basalt, peridotite) with augite, chromite, corundum, spinel, pyrope; rarely in crystalline dolomite.

126 Determinative Mineralogy [Sec. 20

H.

G. 3.4-4.3 GARNET, R3"R2 R" Ca, Mg, Fe, Mn; R'"=A1,

7 1 Fe, Cr, sometimes Ti.

Struct. — Isometric crystals (dodecahedrons, trapezohedrons, Figs. 3, 7, 8); granular, lamellar, compact, disseminated, sand. Cleavage none; parting sometimes distinct, six directions at 60°, 90°, and 120° (110); brittle; fracture conchoidal, uneven.

Color red, brown, black, green, purple, etc. (See varieties, p. 101.) Streak white. Luster vitreous. Transparent to opaque. (See p. 244.) For varieties and occurrence, see p. 101.

7 G. 2.65 QUARTZ (Rock Crystal), SiO2.

Struct. — Prismatic hexagonal crystals striated crosswise, commonly terminated by double rhombohedron (like hexagonal pyramid); granular, disseminated, compact. Cleavage indistinct; brittle; fracture conchoidal.

Color white, colorless, and various shades (see varieties, p. 55). Streak white. Luster vitreous, greasy. Transparent to opaque. (See p. 262.)

For varieties and occurrence, see p. 55.

7 G. 2.6-2.64 CHALCEDONY (Agate, Flint, Hornstone), SiO2.

Struct. — Compact, botryoidal, mammillary, banded. Cleavage none; brittle to tough; fracture conchoidal.

Color white, grayish, and various shades (see varieties, p. 55). Streak white. Luster waxy, vitreous to nearly dull. Translucent to opaque. (See p. 262.)

For varieties and occurrence, see p. 55.

G. 2.9-3.0 Boracite,

Struct. — Isometric-tetrahedral crystals (tetrahedron, cube), small, isolated; groups rare; granular. Cleavage indistinct; brittle; fracture conchoidal, uneven.

Color white, colorless, grayish, yellow, green. Streak white. Luster vitreous. Transparent to opaque. (See pp. 228, 242.)

Commonly disseminated glassy crystals with gypsum, anhydrite, halite, carnallite.

G. 3.0-3.2 TOURMALINE, R Mg, Fe, Ca, Na, K,Li.

Struct. — Prismatic hexagonal-rhombohedral crystals, hemimorphic, curved triangular in cross-section, striated lengthwise (Fig. 58) ; radiating, columnar, compact. Cleavage indistinct; brittle; fracture uneven, conchoidal.

Color black (schorl), blue (indicolite), pink to red (rubellite) brown, green; rarely white or colorless (achroite). Streak white. Luster vitreous, resinous Transparent to opaque. (See pp. 222, 242, 258.)

In pegmatite, gneiss, mica schist, slate, gravels; common at contacts; with quartz, feldspars, beryl, topaz, cassiterite, fluorite.

G. 4.5-4.8 ZIRCON, ZrSiO4; ZrO67.2%; commonly a little Fe.

Struct. — Square tetragonal crystals with prism and pyramid; irregular lumps, disseminated grains. Cleavage indistinct; brittle; fracture uneven.

Sec. 20] Physical Tables 127

H.

Color gray, brown, yellow, green; red transparent (hyacinth); colorless or smoky (jargon). Streak white. Luster adamantine, vitreous. Opaque to transparent. (See p. 262.)

Minute grains in feldspathic igneous rocks; rare in crystalline limestone, gneiss, schist; with magnetite, apatite, biotite, wollastonite, titanite; in placers with gold, corundum, spinel, garnet, monazite.

G. 2.6-2.8 BERYL, a little H, sometimes Na, Li, Cs.

8 Struct. — Prismatic hexagonal crystals, often large rough, and striated lengthwise (Fig. 49); columnar, granular, compact. Cleavage indistinct; brittle; fracture uneven, conchoidal.

Color bright green (emerald), blue, greenish blue (aquamarine}, yellow (golden beryl), pink (rose beryl, morganite), colorless. Streak white. Luster vitreous. Transparent to translucent. (See pp. 244, 260.)

In pegmatite; less common in granite, mica schist, slate; in bituminous limestone; with topaz, tourmaline, garnet, chrysoberyl, rutile.

7 £ G. 3.6-4.6 SPINEL, MgAl2O4; also Fe, Mn, Cr, Zn— see varieties below. 8£ Struct. — Isometric crystals (octahedrons, Fig. 1); granular, compact, disseminated. Cleavage indistinct; brittle; fracture conchoidal.

Color red, yellow, green, blue, brown, black (see varieties below) . Streak white. Luster vitreous, dull. Transparent to opaque. (See p. 262.)

Ruby spinel, MgAl2O4, includes the red and reddish transparent to translucent varieties: spinel ruby, deep red; balas ruby, rose-red; rubicelle, yellow to orange red; almandine, violet; sp. gr. 3.5-3.6. In gem placers with zircon, garnet, magnetite; sometimes in crystalline limestone.

Pleonaste (ceylonite), dark green, brown to black, blue; opaque or nearly so; sp. gr. 3.5-3.6. Chlorospinel, grassgreen; sp. gr. 3.6. Gahnite, ZnAl2O4, dark green, greenish black, bluish black, yellowish, grayish brown; streak grayish; sp. gr. 4.0-4.6. Hercynite, FeAl2O4, black; streak dark grayish green to leek-green; sp. gr. 3.9-4.0. In crystalline limestone, limestone contacts, basic igneous rocks, placers; with calcite, chondrodite, serpentine, brucite, olivine, corundum, graphite, pyroxenes, phlogopite.

Picotite, grading into chromite; dark yellowish brown to greenish brown; translucent to nearly opaque; sp. gr. 4.1. In peridotite, serpentine; with pleonaste, chromite, talc, chlorite, corundum.

9 G. 3.9-4.1 CORUNDUM (Adamantine Spar), A12O3.

Struct. — Rough hexagonal-rhombohedral crystals, prismatic, pyramidal, tabular, tapering (barrel-shaped), often striated; lamellar, granular, compact. Cleavage none; often conspicuous parting three directions at 86° and 94° (lOll); sometimes transverse parting (0001); brittle; tough when compact; fracture uneven, conchoidal.

Color white, gray, brown to black; deep red (ruby); blue (sapphire); black from admixture of magnetite, hematite, or spinel (emery). Streak white. Luster vitreous, adamantine. Transparent to opaque. (See p. 260.)

In peridotite, gneiss, schist, syenite, crystalline limestone; with olivine, chlorite, serpentine, magnetite, spinel, vermiculite; cyanite, diaspore, muscovite.

128 Determinative Mineralogy [Sec. 21

Section 21

Streak yellow, red, or brown; mineral black or nearly so.

H.

1 G. 0.9-1.0 OZOCERITE (Mineral Wax, Native Paraffin), CJI2n+2.

2 Struct. — Amorphous, compact, fibrous, lamellar; plastic; may be sticky. Color black, brownish black, brownish yellow, leek-green. Streak yellowish brown, pale yellow. Luster waxy, greasy, submetallic. Translucent, sometimes greenish opalescence Like wax; greasy feel. Burns with bright smoky flame and odor of paraffin (See p. 212.)

In veins in sedimentary rocks.

1 G. 1.0-1.8. ASPHALT (Asphallum, Mineral Pitch), C, H, O, etc.

3 Struct. — Amorphous solid or very viscous liquid; brittle to flexible; fracture conchoidal.

Color black to brownish black. Streak brownish black. Luster pitch y, resinous, dull. Opaque. Bituminous odor; sticky when plastic. Burns with a pitchy odor and bright flame. (See p. 212.)

Massive deposits (" pitch lakes," etc.) and impregnating sedimentary strata.

1£ G. 2.0-2.1 SULPHUR (Brimstone'), S; traces of Te, Se, As. 2£ Struct. — Granular, fibrous, compact, earthy; reniform, stalactitic, incrusting; orthorhombic crystals, pyramidal (Figs. 34, 35) or tabular. Cleavage indistinct; brittle; fracture conchoidal.

Color yellow, greenish or reddish yellow, brown, gray. Streak white, pale yellow. Luster resinous, greasy, adamantine. Transparent to translucent. (See p. 212.)

In beds with gypsum; about vents of volcanoes and fumaroles; in oxidized parts of sulphide ores; with celestite, gypsum, calcite, aragonite.

2 G. 1.1-1.4 LIGNITE (Brown Coal), C, H, O, etc.; C 65-76%; "Fixed" C 30-60%.

Struct. — Compact amorphous; woody structure common; fracture conchoidal, splintery; may crumble on exposure.

Color brownish black to black. Streak brown to brownish black. Luster dull; resinous (jet). Opaque. Plant remains commonly recognizable. Jet is a black compact variety that takes a polish. Smoky yellow flame. (See p. 212.)

In stratified rocks, sands, clays.

2 G. 1.2-1.5 BITUMINOUS COAL (Soft Coal) C, H, O, etc.; C 76-88%; "Fixed" C 48-73%.

Struct. — Amorphous, compact, lamellar, rarely fibrous; brittle; cubical fracture conspicuous, sometimes conchoidal.

Color and streak black to brownish black. Luster pitchy, vitreous, dull. Opaque. Burns with a smoky yellow flame. (See p. 212.)

Sec. 21] Physical Tables 129

H.

Sometimes shows plant remains; sometimes iridescent. Coking coal becomes pasty in the fire. Cannel coal is dull black, compact, structureless, with conchoidal fracture.

Beds in stratified rocks, with pyrite and marcasite.

8-1 G. 5.8-5.9 PYRARGYRITE (Ruby Silver, Dark Ruby Silver), Ag3SbS3; 3 Ag 59.9%.

Struct. — Disseminated, incrusting, compact; small hexagonal-rhombohedral crystals rare. Cleavage indistinct; brittle; fracture conchoidal, uneven. Color dark red to black. Streak purplish red, cherry-red. Luster adamantine, metallic. Transparent to opaque. (See pp. 198, 216.) In veins with proustite, other silver minerals, galena.

3 G. 4.4-5.1 TETRAHEDRITE (Gray Copper), Cu3SbS3; often Fe, Zn, Pb,

4 Ag, As. Cu46.8%; Ag 3-15%, Freibergite. With increasing As grades into Tennantite, Cu3AsS3.

Struct. — Isometric-tetrahedral crystals (Figs. 13, 14, 17); granular, compact. Cleavage none; brittle; fracture uneven.

Color steel-gray to iron-black. Streak dark gray, black, reddish brown. Luster metallic. Opaque. (See p. 198.)

Sometimes coated with brass-yellow chalcopyrite. In veins with silver lead, and copper ores.

3£ G. 5.9-6.2 Descloizile, PbO 55.4%; ZnO 19.7%; V2O5

22.7%.

Struct. — Small orthorhombic crystals forming drusy crusts; stalactitic, compact, fibrous, radiated. Cleavage none; brittle; fracture small conchoidal to uneven.

Color purplish red to brown and black; cuprodescloizite (containing 5-10% Cu) is brown, green, to greenish black. Streak orange, brownish red, yellowish gray. Luster greasy. Transparent to opaque. (See p. 214.) In veins with pyromorphite, vanadinite, galena.

G. 3.8-3.9 SIDERITE (Spathic Iron, Chalybite, Clay Ironstone, Black 4 Band Ore) FeCO3; Fe 48.3%; sometimes Mg, Mn, Ca.

Struct. — Granular, cleavable, compact; hexagonal-rhombohedral crystals, curved and saddle-shaped common. Cleavage perfect, three directions at 73° and 107° (lOll) ; brittle; fracture uneven.

Color gray, yellow, brown, black, sometimes white. Streak white, pale yellow. Luster vitreous, pearly, dull. Translucent to opaque. (See pp. 218, 248.)

In veins with silver minerals, pyrite and other sulphides, cryolite; beds and concretions in limestone, shale, and coal.

G. 3.9-4.1 SPHALERITE (Blende, Zinc Blend*, Jack, Black Jack, Rosin

4 Jack), ZnS; Zn 67%; may be replaced by Fe up to 18%.

Struct. — Cleavable masses, granular, compact, botryoidal; rounded

isometric-tetrahedral crystals. Cleavage pronounced, six directions at 60°,

90°, and 120° (110); brittle; fracture conchoidal.

130 Determinative Mineralogy [Sec. 21

H.

Color yellow, brown, red, green, black; rarely white or pale gray (cleiophane). Streak white, light to dark brown. Luster resinous, adamantine, submetallic. Transparent to opaque. (See pp. 200, 228, 250.)

Ore deposits and veins with galena, pyrite, chalcopyrite, fluorite, barite; also in limestones.

G. 3.9-4.0 Wurtzite, ZnS; Zn 67%; S 33%.

4 Struct. — Small hemimorphic hexagonal crystals, striated crosswise; fibrous, incrusting, compact. Cleavage indistinct, three directions at 60° and 120° (lOlO); brittle; fracture uneven, splintery.

Color brownish black. Streak brown. Luster resinous. Translucent to opaque. (See pp. 200, 228, 250.)

In veins with sphalerite, galena, quartz, calcite.

3£ G. 5.8-6.1 CUPRITE (Ruby Copper, Red Copper Ore, Red Oxide of Copper), 4 Cu2O; Cu 88.8%; with OH in Hydrocuprite.

Struct. — Compact, granular, earthy; capillary (chalcotrichite) ; isometric crystals. Cleavage indistinct; brittle; fracture uneven.

Color ruby-red, reddish black; orange (hydrocuprite) . Streak brownish red. Luster submetallic, adamantine, dull. Transparent to opaque. (See pp. 204, 214.)

With native copper, malachite, azurite, chrysocolla, limonite, tenorite, chalcocite, chalcopyrite.

3£ G. 4.2-4.4 MANGANITE, MnO- OH; Mn 62.4%; H20 10.3%. 4 Struct. — Prismatic orthorhombic crystals striated lengthwise; often groups or bundles. Cleavage perfect, one direction lengthwise (010); rarely granular stalactitic; brittle; fracture uneven.

Color steel-gray to iron-black. Streak reddish brown to black. Luster metallic, submetallic. Opaque. (See p. 208.)

Often altered to pyrolusite. With ores of manganese and iron; barite, calcite, siderite.

4 G. 4.4-4.6 XENOTIME, YP04; also Er, Ce, Th, etc.

5 Struct. — Tetragonal crystals (prism, pyramid); compact, disseminated, rolled grains. Cleavage distinct, two directions at 90° (110); brittle; fracture uneven, splintery.

Color yellow, brown, red, pale gray. Streak pale brown, yellowish, reddish. Luster greasy, vitreous. Translucent to opaque. (See p. 256.)

Like zircon but softer. In pegmatite and granitic rocks with zircon, rutile; in sands.

4£ G. 4.4-5.4 Thorite (Orangite), ThSiO4; some H2O; sometimes U (Urano- 5 thorite).

Struct. — Tetragonal crystals (prism, pyramid); compact, disseminated. Cleavage indistinct, two directions at 90° (110); brittle; fracture conchoidal.

Color black, brown, orange. Streak orange to dark brown. Luster resinous, greasy. Transparent to translucent. (See p. 252.)

Black variety may inclose the orange. In pegmatite, granite, syenite, with magnetite.

Sec. 21] Physical Tables 131

H.

5 G. 3.6-4.0 LIMONITE (Bog Iron Ore, Brown Hematite, Brown Clay 5 Ironstone, Broivn Ocher, Yellow Ocher), FeO-OH, with

capillary and adsorbed water (compare Goethite below). Fe 55-60%; H2O 12-14%.

Struct. — Amorphous, earthy, fibrous, botryoidal, stalactitic; crystals pseudomorphous after pyrite, marcasite, siderite, etc. Cleavage none; brittle; fracture conchoidal, splintery, uneven, earthy.

Color yellow, brown, black. Streak yellowish brown. Luster metallic, silky, dull; often varnish-like surface. Opaque. (See pp. 204, 208, 218, 250.) In gossan; replacing limestone; nodules in clays; impure in bog iron ore and earthy ocher deposits.

5 G. 4.0-4.4 GOETHITE (Lepidocrocite), FeO- OH; Fe 62.9%; H2O 10.1%.

Struct. — Small tabular, scaly (lepidocrocite) , or acicular orthorhombic crystals; compact, granular, foliated, fibrous. Cleavage distinct, one direction lengthwise (010); brittle; fracture uneven, splintery.

Color yellow, reddish brown, dark brown, black. Streak yellow, yellowish brown. Luster submetallic, adamantine, dull. Translucent to opaque. (See pp. 204, 208, 218, 250.)

In amorphous and fibrous form the essential mineral of limonite, above. With other iron ores; in cavities in hematite and limonite; inclusions giving color to some feldspars and quartz.

5 G. 7.2-7.5 WOLFRAMITE (Wolfram), grades into Ferber- 5£ tie, FeWO4, and Huebnerite, MnWO4; WO3 about 76%.

Struct. — Thick tabular, short columnar, and bladed monoclinic crystals, resembling orthorhombic; cleavable granular, and compact masses. Cleavage perfect, one direction (010); brittle; fracture uneven. May be slightly magnetic.

Color dark gray, black, brownish black, reddish brown . Streak brownish black, black. Luster metallic, submetallic. Opaque. (See pp. 204, 222, 242.)

In veins in granite with cassiterite, quartz, mica, fluorite, apatite, scheelite, pyrite, galena, sphalerite; also in sands.

5 G. 4.7-4.9 Hausmannite, MnMn2O4; Mn 72%.

5 £ Struct. — Granular, compact; simple and twinned acute tetragonal pyramids, striated crosswise. Cleavage perfect, one direction crosswise (001); brittle; fracture uneven.

Color black, brownish black. Streak chestnut-brown. Luster submetallic, greasy. Opaque. (See pp. 208, 250.)

With manganese ores, magnetite, hematite, barite.

5 G. 2.9-3.4 HORNBLENDE (an amphibole), silicate of Ca, Mg, Fe,

6 Al, etc.

Struct. — Granular, columnar, fibrous, radiated; long prismatic monoclinic crystals (pseudohexagonal) often with rhombohedron-like terminations; prism angle 124°; some prisms short. Cleavage perfect, two directions lengthwise at 56° and 124° (110); brittle; fracture uneven, splintery.

132 Determinative Mineralogy [Sec. 21

It.

Color green, black, brown, gray. Streak brown, green, yellow, gray, white. Luster submetallic, vitreous, silky, pearly. Translucent to opaque. (See p. 222, 238.)

Common in igneous and metamorphic rocks with feldspars, pyroxenes, chlorite, quartz, calcite.

5 G. 3.2-3.6 PYROXENE, ranging from Diopside,

6 to Hedenbergite, often some Al, Mn, and Na.

AUGITE (a pyroxene), like common pyroxene above, with A12O3 up to 15% or 20%; sometimes Na and K.

Struct. — Granular, columnar, rarely fibrous; lamellar (diallage); thick monoclinic prisms four- or eight-sided (Figs. 40, 41). Cleavage sometimes distinct, two directions lengthwise at 87° and 93° (110); often prominent parting crosswise (001) ; diallage has fine lamellar parting one direction lengthwise (100); brittle; fracture uneven.

Color bright to dark green, grayish green, black, brown. Streak greenish, brownish, grayish to white. Luster vitreous, submetallic, dull. Transparent to opaque. (See pp. 220, 222, 240.)

Common in basic igneous rocks; in crystalline limestones with garnet, chlorite, amphibole, wollastonite, magnetite, pyrite.

5 G. 3.3-3.5 HYPERSTHENE (a pyroxene), sometimes Al.

6 Struct. — Foliated, cleavable, granular; orthorhombic crystals rare. Cleavage perfect, one direction (010), less distinct two directions (110), at 88°, 92°, and 134°; brittle; fracture uneven.

Color grayish, greenish, and brownish black to bronze. Streak brownish gray, grayish white. Luster metalloidal bronzy, pearly. Opaque to translucent. (See pp. 222, 258.)

In basic igneous rocks with plagioclase feldspars, olivine, amphibole, 'pyroxene, magnetite, titanite; seldom with quartz.'

5 G. 4.5-5.0 ILMENITE (Menaccanite, Titanic Iron Ore), FeTiO3; Fe 36.8%.

6 Ti 31.6%; sometimes Mg.

Struct. — Thin plates, granular, compact, disseminated; pebbles, sand; thick tabular hexagonal-rhombohedral crystals. Cleavage none; brittle; sometimes partings; fracture conchoidal.

Color and streak iron black, brownish black. Luster metallic, submetallic. Opaque. May be slightly magnetic. (See pp. 206, 210.)

Disseminated and masses in igneous rocks, gneiss, schist; with hematite, apatite, magnetite, titanite, rutile, quartz. Common in black sands.

5 G. 3.7-4.7 PSILOMELANE (Black Hematite), MnO2, H2O, BaO, K2O, etc.

6 Struct. — Compact, botryoidal, reniform, stalactitic; no crystals. Cleavage none; brittle; fracture conchoidal, uneven.

Color iron-black, bluish black, steel-gray. Streak black, brownish black. Luster metallic, dull. Opaque. (See p. 208.)

May have sooty coating of pyrolusite or be in layers with it. With other manganese minerals, limonite, barite.

Sec. 21] Physical Tables 133

H.

5 G. 5.6-5.8 Samarskite,

6 Struct. — Compact, apparently amorphous, disseminated; orthorhombic crystals rare. Cleavage none; brittle; fracture conchoidal.

Color velvet-black, black. Streak reddish brown, grayish brown. Luster vitreous, greasy, submetallic. Opaque. (See pp. 204, 242.)

Brilliant luster and conchoidal fracture often conspicuous. In pegmatite with columbite, quartz, mica, feldspars.

5-| G. 4.3-4.6 CHROMITE (Chromic Iron Ore), FeCr2O4; Cr2O3 68%; some Mg and Al.

Struct. — Disseminated, granular, compact; isometric crystals (octahedrons, Fig. 1) small and rare. Cleavage none; indistinct parting four directions at 70|° and 109° (111); brittle; fracture conchoidal, uneven.

Color iron-black, brownish black. Streak dark brown. Luster metallic, submetallic, dull. Opaque. May be slightly magnetic. (See pp. 208, 210, 258, 262.)

In peridotites and serpentine with olivine, enstatite, talc, chlorite, magnetite; in black sands and platinum placers.

5i- G. 9.0-9.7 URANINITE (Pitchblende), UO3, UO2, Pb, Th, La, Y, He, Ra, etc.

Struct. — Botryoidal, granular, lamellar, compact; isometric crystals rare. Cleavage none; brittle; fracture conchoidal.

Color greenish or brownish black, pitch-black. Streak brownish black, grayish black, olive-green. Luster pitch-like, submetallic, dull. Opaque. (See p. 210.)

With ores of silver, lead, copper, bismuth; also in pegmatites.

G. 4.2-4.7 TURGITE ( Hydrohematite, Red Ocher), composition variable; probably Goethite, FeO-OH and Hematite, Fe2O3, in solid solution, with adsorbed and capillary water. Fe 65-66%; H2O 4-6%.

Struct. — Botryoidal, stalactitic, fibrous; earthy (red ocher); no crystals Cleavage none; brittle; fracture uneven, splintery, earthy.

Color red to reddish black. Streak dark red, reddish brown. Luster submetallic, silky, dull. Opaque. (See pp. 204, 208, 218, 250.) Resembles limonite in habit, With limonite and hematite.

G. 4.3-5.8 Fergusoniie, some Ca, Fe, H2O.

Struct. — Disseminated, compact; pyramidal tetragonal crystals rare. Cleavage none; brittle; fracture conchoidal, uneven.

Color brownish black, brown. Streak pale brown. Luster submetallic, vitreous; often dull outside. Translucent, opaque. (See pp. 210, 264.)

Brilliant luster of fresh fracture in striking contrast with dull surface. In granite and pegmatite with quartz, feldspars, zircon, allanite, gadolinite; in placer gravels.

134 Determinative Mineralogy [Sec. 21

H.

5£ G. 4.9-5.3 HEMATITE (Red Iron Ore, Speculate, Specular Iron, Kidney 6£ Ore, Red Ocher, Reddle, Martile), Fe2O3; Fe 70%.

Struct. — Compact, granular, radiated, reniform, botryoidal, columnar; micaceous (specular); earthy (red ocher, reddle); thin tabular hexagonal rhombohedral crystals. Martite, octahedral crystals, pseudomorphous after magnetite. Cleavage none; brittle; sometimes parting; fracture uneven, splintery.

Color steel-gray, red, reddish brown, black. Streak dark red, cherry-red, brownish red. Luster metallic, submetallic, dull. Opaque. (See pp. 204, 208, 218, 250.)

Ore deposits in sedimentary and metamorphic rocks; igneous contacts.

G. 5.1-5.2 FRANKLINITE Fe 39-47%; Mn 10-20%; Zn 5.5-18.5

Struct. — Compact, granular, rounded disseminated grains; isometric

crystals (octahedrons, Fig. 1). Cleavage none; indistinct octahedral parting

(111) four directions at 70£° and 109|°; brittle; fracture conchoidal, uneven;

Color iron-black. Streak black, brownish black, reddish brown. Luster

metallic, dull. Opaque. May be slightly magnetic. (See p. 208.)

In crystalline limestone (New Jersey) with zincite, willemite, rhodonite, tephroite.

6 G. 5.3-7.3 COLUMBITE, with Ta, grading into Tantalite,

Ta2O5 up to 86%.

Struct. — Orthorhombic crystals, short, square, prismatic; granular, disseminated. Cleavage indistinct, one direction (100); brittle; fracture conchoidal, uneven.

Color iron-black, grayish and brownish black; may be iridescent. Streak dark red, brownish black, black. Luster submetallic, greasy, dull. Opaque. (See pp. 204, 210, 242, 264.)

In pegmatite with beryl, lepidolite, tourmaline, spodumene, cassiterite.

6 G. 4.7-4.8 Braunite, 3Mn203-MnSiO3; Mn 64.4%.

6i Struct. — Granular, drusy crusts; minute tetragonal crystals, resembling octahedrons. Cleavage distinct, four directions at 70° and 110° (111); brittle; fracture uneven.

Color brownish black to steel-gray. Streak black, brownish black. Luster submetallic, greasy. Opaque. (See p. 208.)

With manganese minerals, magnetite, hematite, barite.

6 G. 4.1-4.3 TiO2; Ti 60%; often Fe.

7 Struct. — Prismatic tetragonal crystals, striated lengthwise; knee-shaped and rosette twins; acicular, compact, disseminated. Cleavage indistinct; sometimes distinct 2 directions at 45° (100) (110); brittle; fracture uneven.

Color red, reddish brown, black (deep red when transparent). Streak white, gray, pale brown. Luster metallic, adamantine. Transparent to opaque. (See pp. 210, 262.)

In veins with quartz, feldspars, hematite, ilmenite; hair-like inclusions in quartz; in igneous contacts and metamorphic rocks.

Sec. 21, 22] Physical Tables 135

H.

6 G. 6.8-7.1 CASSITERITE (Tinstone), SnO2; Sn 78.6%.

7 Struct. — Granular, disseminated; reniform with radiating fibrous structure (wood tin); sand and pebbles (stream lim); thick prismatic tetragonal crystals, knee-shaped twins common (Fig. 29). Cleavage indistinct, brittle; fracture uneven.

Color brown to black; rarely yellow, red, gray, white. Streak white, grayish, brownish. Luster adamantine, greasy, dull. Transparent to opaque. (See p. 262.)

In granite, gneiss; with wolframite, scheelite, molybdenite, tourmaline, fluorite, topaz, apatite, lepidolite; in pegmatites; in sands and gravels.

Section 22

Streak yellow, red, or brown; mineral yellow, red or brown.

0 G. 3.6-4.0 LIMONITE (Bog Iron Ore, yellow Ocher}, FeO-OH with capil-

1 lary and adsorbed water; Fe 55-60%; H2O 12-14%. Yellow, yellowish brown, earthy. (See p. 131.)

0 G. 4.0-44 GOETHITE (Yellow Ocher}, FeO-OH; Fe 62.9%; H2O 10.1%

1 Yellow, yellowish brown, earthy. (See p. 142.)

0 G. 4.9-5.0 GREENOCKITE (Cadmium Blende), CdS; Cd 77.7%

1 Bright yellow powder on zinc ores, calcite, etc. (See p. 140.)

0 CARNOTITE, approx. (K2, 2U2O3 V2O5 nH2O ; V2O5 20% ;

1 U203 63%.

Dull opaque canary yellow powder, minute waxy scales; rarely solid masses; greasy feel; cuts like paraffin. Affects photographic plate in one to seven days.

In cracks and pores of sandstone with roscoelite and other uranium and vanadium minerals. Resembles beaverite, below. (See p. 228.)

0 Beaverite,

1 Dull, earthy, friable; canary-yellow; microscopic hexagonal plates. (See pp. 214, 216.)

In oxidized silver, lead, zinc, and copper ores. Resembles carnotite.

0 G. 4.9-5.3 HEMATITE (Red Iron Ore, Red Ocher), Fe2O3; Fe 70%.

1 Red powdery or earthy masses. (See p. 134.)

0 G. 4.2-4.7 TURGITE (Hydrohematite Red Ocher), hydrous ferric oxide;

1 Fe 65-66%.

Red powdery or earthy masses. (See p. 144.)

0 G. 8.0-8.2 CINNABAR (Natural Vermilion), HgS; Hg 86.2%.

1 Scarlet to cochineal-red and brownish red, earthy; heavy. (See p. 137.)

136 Determinative Mineralogy [Sec. 22

H.

1 G. 5.6-5.7 lodyrite (I odargyrite) , Agl; Ag 46%.

Struct. — Thin scales, lamellar, compact; hexagonal prisms. Cleavage conspicuous, one direction crosswise (0001); sectile; thin flakes flexible.

Color yellow, yellowish green, brownish. Streak yellow. Luster resinous, wax-like. Translucent. (See p. 216.)

In veins with other silver minerals, vanadinite, descloizite.

1 G. 0.9-1.0 OZOCERITE (Mineral Wax, Native Paraffin'), CwH2n+2.

2 Struct. — Amorphous, compact, fibrous, lamellar; plastic, may be sticky. Color black, brownish black, brownish yellow, leek-green. Streak yellowish brown, pale yellow. Luster waxy, greasy, submetallic. Translucent, sometimes greenish opalescence. (See p. 212.) Like wax, greasy feel. Burns with bright smoky flame and odor of paraffin.

In veins in sedimentary rocks.

1 G. 4.5 Molybdite (Molybdic Ocher), MoO3 59.4%.

2 Struct. — Earthy powder, crusts; rarely fibrous, radiating, or hair-like orthorhombic crystals. Cleavage distinct, one direction crosswise (001); brittle.

Color and streak straw-yellow, yellowish white. Luster dull, silky. Translucent to opaque. (See p. 228.)

With molybdenite, of which it is an alteration product.*

1 G. 1.0-1.8 ASPHALT (Asphaltum, Mineral Pitch), C, H, O, etc.

3 Struct. — Amorphous solid or very viscous liquid; fracture conchoidal; brittle to flexible and plastic.

Color black to brownish black. Streak brownish black. Luster pitchy, resinous, dull. Opaque. Bituminous odor; sticky when plastic. Burns, with a pitchy odor and bright flame. (See p. 212.)

Massive deposits ("pitch lakes," etc.) and impregnating sedimentary strata.

1£ G. 3.5-3.6 REALGAR, AsS; As 70.1%.

2 Struct. — Granular, earthy incrustations, disseminated; rarely short monoclinic prisms, striated lengthwise. Cleavage distinct, one direction lengthwise (010); slightly sectile; fracture conchoidal.

Color deep red to orange, becoming yellow (orpiment) on long exposure to light. Streak orange-yellow. Luster resinous, adamantine, dull. Transparent to translucent (See p. 212.)

In veins with orpiment, stibnite, native arsenic, pyrite; disseminated in clay, dolomite, etc.

G. 3.4-3.5 ORPIMENT, As2S3; As 61%.

2 Struct. — Foliated, granular, earthy incrustations; rarely small monoclinic crystals. Cleavage distinct, one direction (010); thin flakes flexible; slightly sectile.

Sec. 22] Physical Tables 137

H.

Color and streak lemon-yellow. Luster resinous, greasy; pearly on cleavage. Translucent to nearly opaque. (See p. 212.)

In veins with realgar, stibnite, barite, calcite, pyrite; forms from realgar on long exposure to light.

±i G. 2.0-2.1 SULPHUR (Brimstone), S; traces of Te, Se, As. 2% Struct. — Granular, fibrous, compact, earthy; reniform, stalactitic, incrusting; orthorhombic crystals, pyramidal (Figs. 34, 35) or tabular. Cleavage indistinct; brittle; fracture conchoidal.

Color yellow, greenish or reddish yellow, brown, gray. Streak white, pale yellow. Luster resinous, greasy, adamantine. Transparent to translucent. (See p. 212.)

In beds with gypsum; about vents of volcanoes and fumaroles; in oxidized parts of sulphide ores; with celestite, gypsum, calcite, aragonite.

If G. 2.9-3.0 ERYTHRITE (Cobalt Bloom, Red Cobalt, Cobalt Ocher), 2% CoO 37.5%; sometimes Ni, Fe, Ca.

Struct. — Minute acicular monoclinic crystals, incrusting, radiating; powdery, earthy. Cleavage perfect, one direction lengthwise (010); sectile; thin laminae flexible.

Color crimson, peach-red, pink; fades on exposure. Streak pale red, pink. Luster adamantine, dull. Transparent to opaque. (See p. 218.)

Alteration product of cobalt-arsenic minerals; incrusting cobaltite smaltite, chloanthite, niccolite.

If G. 2.1 COPIAPITE (Misy), often Al and Mg. 2% . Struct. — Granular, scales, crusts, powder; six-sided tabular monoclinio crystals rare. Cleavage one direction (010) ; brittle; fracture uneven, scaly, earthy.

Color yellow to greenish and brownish yellow. Streak yellowish. Luster pearly, dull. Translucent to opaque. Disagreeable metallic taste. (See p. 218.)

With iron and copper sulphates from oxidation of sulphides.

2 G. 8.0-8.2 CINNABAR (Natural Vermilion, Mercury Blende), HgS; 3! Hg 86.2%.

Struct. — Granular, earthy, incrusting; small thick tabular hexagonalrhombohedral crystals rare. Cleavage indistinct, three directions at 60° and 120° (lOTO); brittle to sectile; fracture uneven.

Color purplish red to brownish red. Streak scarlet to brownish red. Luster adamantine, dull. Transparent to opaque. (See pp. 202, 212.)

Veins and disseminated in sandstone and limestone with pyrite, marcasite, realgar, stibnite, barite, opal, quartz, sulphur, mercury.

2 G. 5 5-5.6 PROUSTITE (Ruby Silver, Light Ruby Silver), Ag3AsS3; Ag 65.4%. 2 Struct. — Compact, disseminated, incrusting; small hexagonal-rhombo-

hedral crystals rare. Cleavage three directions at 72° and 108° (lOll), not

conspicuous; brittle; fracture conchoidal.

138 Determinative Mineralogy [Sec. 22

H.

Color and streak scarlet to brownish red. Luster adamantine, dull. Transparent to translucent. (See pp. 196, 216.)

In veins with pyrargyrite and other silver minerals and galena.

2 G. 1.1-1.4 LIGNITE (Brown Coal), C, H, O, etc.; C 65-76%; "fixed" 3£ C 30-60%.

Struct. — Compact, amorphous; woody structure common; fracture conchoidal, splintery; may crumble on exposure.

Color brownish black to black. Streak brown to brownish black. Luster dull; resinous (jet). Opaque. Plant remains commonly recognizable. Jet is a black compact variety that takes a polish. Smoky yellow flame. (See p. 212.)

In stratified rocks, sands, clays.

2 G. 3.1-3.2 Autunite, CaOJOaMPO-SHaO; U0362.7%. 2 Struct. — Thin tabular orthorhombic (pseu do tetragonal) crystals; foliated and scaly micaceous aggregates. Cleavage perfect, one direction (001); flakes brittle.

Color lemon to sulphur-yellow. Streak yellowish. Luster pearly, subadamantine. Transparent to translucent. (See p. 228.)

With uraninite and other uranium minerals; with silver, tin and iron ores. Commonly in pegmatite.

2 G. 5.8-6.0 Bromyrite (Bromargyrite) , AgBr; Ag 57.4%.

3 Struct. — Compact, incrusting, concretionary; isometric crystals rare. Cleavage none; sectile; fracture uneven.

Color bright yellow to amber-yellow, greenish; often grass-green or. olivegreen externally; little altered on exposure. Streak pale yellow, greenish yellow. Luster resinous, adamantine. Transparent to translucent. (See p. 216.)

With cerargyrite, embolite, cerusite, calcite, hi oxidized silver ores.

2J G. 9.0 GALA VERITE, Au 38-41% Ag 2-4%.

Struct. — Compact; small monoclinic crystals rare. Cleavage none; brittle; fracture uneven.

Color light bronze-yellow. Streak yellowish gray. Luster metallic. Opaque. (See p. 206.)

In veins with gold, sylvanite, petzite, tetrahedrite, pyrite, fluorite.

2 G. 8.8-8.9 COPPER (Native Copper), Cu; often some Ag, Bi, Hg, etc.

3 Struct. — Scales, plates, lumps, branching aggregates; isometric crystals, commonly distorted. Cleavage none; ductile and malleable; fracture hackly.

Color copper-red, tarnish black, blue, green. Streak copper-red, shiny. Luster metallic. Opaque. (See p. 202.)

In amygdules and veins in basic lavas and in accompanying conglomerate, sandstone, shale, etc., with silver, zeolites, datolite, epidote, quartz, calcite; in oxidized zone of other copper ores.

Sec. 22] Physical Tables 139

H.

2£ G. 15.6-19.3 GOLD (Native Gold}, Au; commonly some Ag, sometimes

3 Cu, Bi, etc.; Ag 20% or more, Electrum.

Struct. — Grains, scales, lumps; rarely small isometric crystals, commonly distorted. Cleavage none; ductile and malleable; fracture hackly.

Color gold-yellow, brass-yellow, pale yellow; does not tarnish. Streak gold-yellow, shiny. Luster metallic. Opaque. (See p. 202.)

In veins with quartz, pyrite, galena, sphalerite, and other sulphides; in sands and gravels (placers) .

G. 5.8-5.9 PYRARGYRITE (Ruby Silver, Dark Ruby Silver), Ag3SbS3; 3 Ag 59 .9%.: some As.

Struct. — Disseminated, incrusting, compact; small hexagonal-rhombohedral crystals rare. Cleavage indistinct; brittle; fracture conchoidal, uneven.

Color dark red to black. Streak purplish red, cherry-red. Luster adamantine, metallic. Transparent to opaque. (See pp. 198, 216.) In veins with proustite, other silver minerals, galena.

2 G. 5.9-6.1 CROCOITE, PbCrO4; Pb 63.9%.

3 Struct. — Monoclinic prismatic crystals; acicular, granular, columnar, incrusting. Cleavage distinct, two directions at 86° and 104° (110), less distinct two other directions (100) (001); sectile; fracture conchoidal, uneven.

Color bright red. Streak orange-yellow. Luster adamantine, vitreous. Translucent. (See p. 214.)

In veins with galena, quartz, pyrite, vanadinite, wulfenite.

2£- G. 2.7-2.8 Polyhalite, KaMgCaaCSOOHaO; K2O 15.6%. 3 Struct. — Fibrous, lamellar, compact; monoclinic (?). Cleavage distinct, one direction; brittle; fracture splintery.

Color flesh- to brick-red; yellowish red to white. Streak white, reddish to yellowish white. Luster greasy, pearly. Translucent to opaque. Taste weakly bitter and astringent. (See p. 226.) In beds of salt, gypsum, and clay.

3 G. 6.6-7.2 VANADINITE, Pb 73%; V2O5 19.4%; sometimes

P and As.

Struct. — Small hexagonal crystals (prisms, Fig. 49), sometimes hollow; fibrous, incrusting, compact, globular. Cleavage none; brittle; fracture uneven, conchoidal,

Color ruby-red, brown, yellow. Streak white, pale yellow. Luster resinous on fracture. Translucent to opaque. (See p. 214.)

In oxidized parts of lead ores; in gold and silver veins; with pyromorphite, wulfenite, galena.

3 G. 4.1-4.6 Olivenite (Wood Copper}, Cu 49.8%;

As2O5 40.7%.

Struct. — Fibrous, velvety crusts, rsniform, granular, earthy; prismatic and acicular orthorhombic crystals. Cleavage none; brittle; fracture conchoidal uneven.

140 Determinative Mineralogy [Sec. 22

H.

Color olive to blackish green, brown, straw-yellow, grayish white. Streak olive-green, brown. Luster adamantine, vitreous. Transparent to opaque. (See p. 216.)

In the oxidized zone with copper minerals.

3 G. 4.9-5.0 GREENOCKITE (Cadmium Blende), CdS; Cd 77.7%.

3£ Struct. — Earthy coatings, powdery; rarely small hexagonal crystals. Cleavage inconspicuous, three directions at 60° and 120° (1120); brittle; fracture conchoidal.

Color yellow, orange-yellow, greenish yellow. Streak orange-yellow. Luster resinous, adamantine, dull. Translucent to opaque. (See p. 250.)

With sphalerite, smithsonite, galena, calcite.

3£ G. 5.9-6.2 Descloizite, PbO 55.4%; ZnO 19.7%;

V205 22.7%.

Struct. — Small orthorhombic crystals forming drusy crusts; stalactitic, compact, fibrous, radiated. Cleavage none; brittle; fracture small conchoidal to uneven.

Color purplish red to brown and black; cuprodescloizite (containing 5-10% Cu) is brown, green, to greenish black. Streak orange, brownish red, yellowish gray. Luster greasy. Transparent to opaque. (See p. 214.) In veins with pyromorphite, vanadinite, galena.

G. 3.8-3.9 SIDERITE (Spathic Iron, Chalybite, Clay Ironstone, Black

4 Band Ore), FeCO3; Fe 48.3%; sometimes Mg, Mn, Ca. Struct. — Granular, cleavable, compact; hexagonal-rhombohedral crystals,

curved and saddle-shaped common. Cleavage perfect, three directions at 73° and 107° (lOll); brittle; fracture uneven.

Color gray, yellow, brown, black, sometimes white. Streak white, pale yellow. Luster vitreous, pearly, dull. Translucent to opaque. (See pp. 218, 248.)

In veins with silver minerals, pyrite and other sulphides, cryolite; beds and concretions in limestone, shale, and coal.

G. 3.9-4.1 SPHALERITE (Blende, Zinc Blende, Jack, Black Jack, Rosin 4 Jack), ZriS; Zn 67%; may be replaced by Fe up to 18%.

Struct. — Cleavable masses, granular, compact, botryoidal; rounded isometric-tetrahedral crystals. Cleavage pronounced, six directions at 60°, 90°, and 120° (110); brittle; fracture conchoidal.

Color yellow, brown, red, green, black; rarely white or pale gray (cleiophane). Streak white, light to dark brown. Luster resinous, adamantine, submetallic. Transparent to opaque. (See pp. 200, 228, 250.)

Ore deposits and veins with galena, pyrite, chalcopyrite, fluorite, barite; also in limestones.

G. 3.9-4.0 Wurtzite, ZnS; Zn67%; S33%.

4 Struct. — Small hemimorphic hexagonal crystals, striated crosswise;

fibrous, incrusting, compact. Cleavage indistinct, three directions at 60°

and 120° (1010); brittle; fracture uneven, splintery.

Sec 22] Physical Tables 141

H.

Color brownish black. Streak brown. Luster resinous. Translucent to opaque. (See pp. 200, 228, 250.)

In veins with sphalerite, galena, quartz, calcite.

G. 5.8-6.1 CUPRITE (Ruby Copper, Red Copper Ore, Red Oxide of Copper), 4 Cu2O; Cu 88.8%; with OH in Hydrocuprite.

Struct. — Compact, granular, earthy, capillary (chalcotrichite)', isometric crystals. Cleavage indistinct; brittle; fracture uneven.

Color ruby-red, reddish black; orange (hydrocuprite) . Streak brownish red. Luster submetallic, adamantine, dull. Transparent to opaque.

With native copper, malachite, azurite, chrysocolla, limonite, tenorite, chalcocite, chalcopyrite. (See pp. 204, 214.)

3£ G. 6.5-71 PYROMORPHITE (Green Lead Ore), Pb76.3%;

Struct. — Small prismatic hexagonal crystals, often rounded, barrelshaped, sometimes hollow; incrusting, reniform, disseminated. Cleavage none; brittle; fracture onchoidal, uneven.

Color green, yellow, brown, white, gray. Streak pale yellow, greenish yellow, white. Luster resinous, greasy, adamantine. Translucent to opaque. (See p. 214.)

In oxidized parts of lead veins with galena, cerusite, mimetite, barite, limonite.

4 G. 5.4-5.7 ZINCITE (Red Zinc Ore), ZnO; Zn 80.3%; commonly Mn. 4 5 Struct. — Lamellar, granular; rarely hemimorphic hexagonal crystals. Cleavage distinct, one direction (0001); sometimes distinct 3 other directions at 60° (1010); brittle; fracture uneven.

Color deep red to orange. Streak orange-yellow. Luster adamantine. Translucent to opaque. (See p. 250.)

In crystalline limestone with franklinite, willemite, rhodonite.

4 G. 4.4-4.6 XENOTIME, YPO4; also Er, Ce, Th, etc.

5 Struct. — Tetragonal crystals (prism, pyramid); compact, disseminated, rolled grains. Cleavage distinct, two directions at 90° (110); brittle; fracture uneven, splintery.

Color yellow, brown, red, pale gray. Streak pale brown, yellowish, reddish. Luster greasy, vitreous. Translucent to opaque. (See p. 256.)

Like zircon but softer. In pegmatite and granitic rocks with zircon, rutile; in sands.

G. 5.9-6.2 SCHEELITE, CaWO4; WO3 80.6%; some Mo; sometimes Cu 5 (Cuproscheelite) .

Struct. — Small pyramidal tetragonal crystals, resembling octahedrons, sometimes tabular; incrusting, granular, compact; Cleavage inconspicuous, four directions at 80°, 110°, and 130|° (111); brittle; fracture conchoidal, uneven.

142 Determinative Mineralogy [Sec. 22

H.

Color white, yellow, brownish, greenish, reddish. Streak white to yellowish. Luster greasy, adamantine. Transparent to translucent. (See pp. 234, 254, 258.)

In veins and contacts with quartz, cassiterite, topaz, fluorite, apatite, molybdenite.

4£ G. 4.4-5.4 Thorite (Orangite), ThSiO4; some H2O; sometimes U (Urano- 5 thorite).

Struct. — Tetragonal crystals (prism, pyramid); compact, disseminated. Cleavage indistinct, two directions at 90° (110); brittle; fracture conchoidal. Color black, brown, orange. Streak orange to dark brown. Luster resinous, greasy. Transparent to translucent. (See p. 252.)

Black variety may inclose the orange. In pegmatite, granite, syenite, with magnetite.

5 G. 3.6-4.0 LIMONITE (Bog Iron Ore, Brown Hematite, Brawn Clay Ironstone, Brown Ocher, yellow Ocher), FeO-OH with capil-

lary and adsorbed water (compare Goethite, below); Fe 55-60%; H2O 12-14%.

Struct. — Amorphous, earthy, fibrous, botryoidal, stalactitic; crystals pseudomorphous after pyrite, marcasite, siderite, etc. Cleavage none; brittle; fracture conchoidal, splintery, uneven, earthy.

Color yellow, brown, black. Streak yellowish brown. Luster metallic, silky, dull; often varnish-like surface. Opaque. (See pp. 204, 208, 218, 250.) In gossan; replacing limestone; nodules in clays; impure in bog iron ore and earthy ocher deposits.

5 G. 4.0-4.4 GOETHITE (Lepidocrosite), FeO- OH; Fe 62.9%; H20 10.1%.

5 Struct. — Small tabular, scaly (lepidocrosite) , or acicular orthorhombic crystals; compact, granular, foliated, fibrous. Cleavage distinct, one direction lengthwise (010); brittle; fracture uneven, splintery.

Color yellow, reddish brown, dark brown, black. Streak yellow, yellowish brown. Luster submetallic, adamantine, dull. Translucent to opaque. (See pp. 204, 208, 218, 250.)

In amorphous and fibrous form the essential mineral of limonite, above. With other iron ores; in cavities in hematite and limonite; inclusions giving color to some feldspars and quartz.,

5 G. 7.2-7.5 WOLFRAMITE (Wolfram), grades into Fer-

berite, FeWO4, and Huebnerite, MnWO4; WO3 about 76%.

Struct. — Thick tabular, short columnar, and bladed monoclinic crystals,

resembling orthorhombic; cleavable, granular, compact. Cleavage perfect,

one direction (010); brittle; fracture uneven. May be slightly magnetic.

Color dark gray, black, brownish black, reddish brown. Streak brownish black, black. Luster metallic, submetallic. Opaque. (See pp. 204, 222, 242.) In veins in granite with cassiterite, quartz, mica, fluorite, apatite, scheelite, pyrite, galena, sphalerite; also in sands.

Si;c. 22j 1'HYSICAL TABLES 143

H.

5 G. 7.3-7.7 NICCOLITE (Copper Nickel), NiAs; Ni 43.9%; some Fe, Co, Sb, S.

Struct. — Compact, disseminated; small hexagonal crystals rare. Cleavage none; brittle; fracture uneven.

Color light copper-red, tarnish gray to blackish. Streak brownish black. Luster metallic. Opaque. (See p. 196.)

May have coating of green (annabergite) . With cobalt, nickel, and silver minerals, bismuth, arsenic, calcite.

5 G. 4.7-4.9 Hausmannite, MnMn2O4; Mn 72%.

5 1 Struct. — Granular, compact; simple and twinned acute tetragonal pyramids, striated crosswise. Cleavage perfect, one direction crosswise (001); brittle; fracture uneven.

Color black, brownish black. Streak chestnut-brown. Luster submetallic, greasy. Opaque. (See pp. 208, 250.)

With manganese ores, magnetite, hematite, barite.

5 G. 2.9-3.4 HORNBLENDE (an amphibole), silicate of Ca, Mg, Fe, Al, etc.

6 Struct. — Granular, columnar, fibrous, radiated; long prismatic monoclinic crystals (pseudohexagonal), often with rhombohedron-like terminations; prism angle 124°; some prisms short. Cleavage perfect, two directions lengthwise at 56° and 124° (110); brittle; fracture uneven, splintery.

Color green, black, brown, gray. Streak brown, green, yellow, gray, white. Luster submetallic, vitreous, silky, pearly. Translucent to opaque. (See pp. 222, 238.)

Common in igneous and metamorphic rocks with feldspars, pyroxenes, chlorite, quartz, calcite.

5 G. 3.2-3.6 PYROXENE, ranging from Diopside,

6 to Hedenbergite, often some Al, Mn, and Na.

AUGITE (a pyroxene), like common pyroxene above, with A12O3 up to 15% or 20%; sometimes Na and K.

Struct. — Granular, columnar, rarely fibrous; lamellar (diallage)', thick monoclinic prisms four- or eight-sided (Figs. 40, 41). Cleavage sometimes distinct, two directions lengthwise at 87° and 93° (110); often prominent parting crosswise (001); diallage has fine lamellar parting one direction lengthwise (100); brittle; fracture uneven.

Color bright to dark green, grayish green, black, brown. Streak greenish, brownish, grayish to white. Luster vitreous, submetallic, dull. Transparent to opaque. (See pp. 220, 222, 240.)

Common in basic igneous rocks; in crystalline limestones with garnet, chlorite, amphibole, wollastonite, magnetite, pyrite.

5 G. 3.3-3.5 HYPERSTHENE (a pyroxene), sometimes Al.

6 Struct. — Foliated, cleavable, granular; orthorhombic crystals rare. Cleavage perfect, erne direction (010), less distinct in two directions (110), 43 1 °, 88°, and 92°; brittle; fracture uneven.

144 Determinative Mineralogy [Sec. 22

H.

Color grayish, greenish, and brownish black to bronze. Streak brownish gray, grayish white. Luster metalloidal, bronzy, pearly. Opaque to translucent. (See pp. 222, 258.)

In basic igneous rocks with plagioclase feldspars, olivine, amphibole, pyroxene, magnetite, titanite; seldom with quartz.

5£ G. 4.3-4.6 CHROMITE (Chromic Iron Ore), FeCr2O4; Cr2O3 68%; some Mg and Al.

Struct. — Disseminated, granular, compact; isometric crystals (octahedrons, Fig. 1) small and rare. Cleavage none; indistinct parting four directions at 70|° and 109|° (111); brittle; fracture conchoidal, uneven.

Color iron-black, brownish black. Streak dark brown. Luster metallic, submetallic, dull. Opaque. May be slightly magnetic. (See pp. 208, 210, 258, 262.)

In peridotites and serpentine; with olivine, enstatite, talc, chlorite, magnetite; in black sands and platinum placers.

G. 4.3-5.8 Fergusonite, some Ca, Fe, H20. 6 Struct. — Disseminated, compact; pyramidal tetragonal crystals rare. Cleavage none; brittle; fracture conchoidal, uneven.

Color brownish black, brown. Streak pale brown. Luster submetallic, vitreous; often dull outside. Translucent, opaque. (See pp. 210, 264.)

Brilliant luster of fresh fracture in striking contrast with dull surface. In granite and pegmatite with quartz, feldspars, zircon, allanite, gadolinite; in placer gravels.

G. 4.2-4.7 TURGITE (Hydrohematite, Red Ocher), composition variable; 6 probably Goethite, FeO OH, and Hematite, Fe2O3, in solid

solution, with adsorbed and capillary water. Fe 65-66%; H2O 4-6%

Struct. — Botryoidal, stalactitic, fibrous, earthy (red ocher); no crystals Cleavage none; brittle; fracture uneven, splintery, earthy.

Color red to blackish red. Streak dark red, reddish brown. Luster submetallic, silky, dull. Opaque. (See pp. 204, 208, 218, 250.) Resembles limonite in habit. With limonite and hematite.

5J G. 4.9-5.3 HEMATITE (Red Iron Ore, Specularite, Specular Iron, Kidney 6£ Ore, Red Ocher, Reddle, Martite), Fe2O3; Fe 70%.

Struct. — Compact, granular, radiated, feniform, botryoidal, columnar; micaceous (specular); earthy (red ocher, reddle); thin tabular hexagonalrhombohedral crystals. Martite, octahedral crystals, pseudomorphous after magnetite. Cleavage none; sometimes parting; brittle; fracture uneven, splintery.

Color steel-gray, red, reddish browTi, black. Streak dark red, cherry-red, brownish red. Luster metallic, submetallic, dull. Opaque. (See pp. 204, 208, 218, 250.)

Ore deposits in sedimentary and metamorphic rocks; igneous contacts.

Sec. 22, 23] Physical Tables 145

H.

6 G. 4.1-4.3 RUTILE (Nigrine), TiO2; Ti 60%; often Fe.

7 Struct. — Prismatic tetragonal crystals, striated lengthwise; knee-shaped and rosette twins; acicular, compact, disseminated. Cleavage indistinct; sometimes distinct 2 directions at 45° (100) (110); brittle; fracture uneven.

Color red, reddish brown, black (deep red when transparent). Streak white, gray, pale brown. Luster metallic, adamantine. Transparent to opaque. (See pp. 210, 262.)

In veins with quartz, feldspars, hematite, ilmenite; hair-like inclusions in quartz; in igneous contacts and metamorphic rocks

6 G. 6.8-7.1 CASSITERITE (Tinstone}, SnO2; Sn 78.6%.

7 Struct. — Granular, disseminated; reniform with radiating fibrous structure (wood tin)', sand and pebbles (stream tin); thick prismatic tetragonal crystals, knee-shaped twins common (Fig. 29). Cleavage indistinct; brittle; fracture uneven.

Color brown to black; rarely yellow, red, gray, white. Streak white, grayish, brownish. Luster adamantine, greasy, dull. Transparent to opaque. (See p. 262.)

In granite, gneiss; with wolframite, scheelite, molybdenite, tourmaline, fluorite, topaz, apatite, lepidolite; in pegmatites; in sands and gravels.

SECTION 23 Streak blue or green.

1 G. 3.2-3.3 BLUE ASBESTOS (Crocidolite) , approx. NaFe"Fe'"

2 Struct. — Long delicate flexible fibers, easily separable. Color and streak lavender-blue. (See p. 148.)

1 G. 2.2-2.4 GLAUCONITE (Greensand, Green Earth), approx.

2 K20 6-9%; some Al and Mg.

Struct. — Granular, earthy, disseminated; amorphous. Cleavage none; brittle; fracture earthy, uneven.

Color yellowish green, grayish green, blackish green. Streak light green, greenish white. Luster vitreous, dull. Opaque. (See p. 220.)

Abundant in greensand beds (so-called marls); disseminated in sands, clays, sandstones, limestones.

1 G. 2.6-3.0 CHLORITE (Clinochlore, Pennine, Prochlorite), H, Fe, Mg, Al 2 £ silicates.

Struct. — Foliated, scaly, granular, compact, earthy; tabular six-sided monoclinic crystals rare. Cleavage perfect, one direction (001); thin flakes flexible, tough, not elastic; fracture scaly, earthy; slight soapy feel.

Color light to dark green. Streak white, greenish white, grayish. Luster pearly, vitreous, dull. Translucent to opaque. (See pp. 236, 254.)

In schists, greenstones, green slates, serpentines, peridotites; with map netite, chromite, garnet, talc, pyroxene, serpentine, corundum.

146 Determinative Mineralogy [Sec. 23

H.

1 G. 3.0-3.1 ANNABERGITE (Nickel Bloom, Nickel Ocher, Nickel Green),

2% Ni 29.4%; sometimes Co and Ca.

Struct. — Earthy, incrusting, compact, stains; capillary monoclinic crystals rare. Cleavage none; brittle; fracture uneven.

Color apple-green, light green. Streak pale green, greenish white. Luster dull, vitreous. Opaque to translucent. (See p. 218.)

Oxidation product of nickel arsenides; with smaltite, niccolite, chloanthite, calcite.

1 G. 2.3-2.8 GARNIERITE (Noumeite, Genthite), approx. MH2O ; 4 Ni 8-35%.

Struct. — Compact, botryoidal, incrusting, earthy. Cleavage none; brittle; fracture conchoidal, earthy. Sometimes greasy feel.

Color pale yellowish green to emerald-green. Streak white, greenish white. Luster greasy, resinous, dull. Opaque. (See pp. 254, 258.)

Veins in peridotites, serpentine; with chromite, talc, chlorite.

G. 2.6-2.7 VIVIANITE (Blue Iron Earth), P2O6 28.3%.

2 Struct. — Radial fibrous, earthy; prismatic and tabular monoclinic crystals. Cleavage distinct, one direction (010); sectile; fracture splintery, earthy; thin flakes flexible.

Color blue, green, greenish black; colorless when fresh. Turns blue on exposure to light or grinding in a mortar. Streak white, blue, greenish-blue. Luster pearly on cleavage; vitreous, dull. Transparent' to opaque. (See p. 218.)

In clay, marl, peat; in cavities of fossils; with limonite; in veins with pyrrhotite, pyrite, gold.

2 G. 2.9-3.0 ROSCOELITE (Vanadium Mica), approx.

V2O3 20-29%; some Mg, Fe. Struct. — Minute micaceous scales.

Color dark green to brown. Luster pearly. Translucent. (See p. 236.) In veins with quartz, gold, and tellurium; disseminated in sandstone with carnotite.

2 G. 2.0-2.2 CHRYSOCOLLA, approx. CuSi03-2H2O; variable; Cu 20-50%.

3 Struct. — Amorphous, compact, reniform, incrusting, stains, earthy. Cleavage none; brittle; fracture conchoidal.

Color green, greenish blue, blue; brown to black from impurities. Streak white to pale blue or green. Luster vitreous, greasy, dull. Translucent to opaque. (See p. 254.)

In oxidized parts of copper deposits, with malachite, azurite, cuprite, native copper.

3 G. 4.1-4.6 Olivenite (Wood Copper), Cu 49.8%; As205 40.7% Struct. — Fibrous, velvety crusts, reniform, granular, earthy; prismatic and acicular orthorhombic crystals. Cleavage none; brittle; fracture conchoidal, uneven.

Sec. 23] Physical Tables 147

Color olive to blackish green, brown, straw-yellow, grayish white. Streak olive-green, brown. Luster adamantine, vitreous. Transparent to opaque. (Sefe p. 216.)

In the oxidized zone with copper minerals.

3 G. 2.6-2.7 Zaratite (Emerald Nickel, Texasite),

Ni 46.8%.

Struct. — Incrusting, mammillary, minutely crystalline, compact. Cleavage none; brittle; fracture smooth.

Color emerald-green. Streak green. Luster vitreous. Transparent to translucent. (See p. 248.)

In peridotite and serpentine with chromite; in nickeliferous magnetite.

3 G. 3.7-3.8 ATACAMITE, Cu 59.5%; Cl 16.6%; H2O 12.7%. 3£ Struct. — Crystalline aggregates, fibrous, granular, incrusting; slender

prismatic orthorhombic crystals, striated lengthwise. Cleavage distinct, one direction lengthwise (010) ; brittle; fracture conchoidal.

Color emerald-green, blackish green. Streak apple-green. Luster vitreous, adamantine. Transparent to opaque. (See p. 214.)

With malachite and other secondary copper minerals, also sulphides, limonite, hematite.

3£ G. 3.9-4.0 MALACHITE (Green Copper, Green Carbonate of Copper),

4 Cu 57.4%.

Struct. — Radial fibrous, botryoidal, stalactitic, incrusting, earthy; slender monoclinic crystals in tufts. Cleavage one direction crosswise (001); brittle; fracture conchoidal, splintery.

Color emerald-green, grass-green, dark green. Streak light green. Luster adamantine, silky, dull. Translucent to opaque. (See p. 214.)

With other oxidized copper minerals, sulphides, native copper.

3£ G. 3.7-3.8 AZURITE (Chessylite, Blue Copper, Blue Carbonate of Copper), 4 *StSOHMeO,)tj Cu 55.2%.

Struct. — Short prismatic or tabular monoclinic crystals; radiating, botryoidal, incrusting, earthy. Cleavage distinct, two- directions at 121° (021); brittle; fracture conchoidal.

Color azure-blue, dark blue. Streak blue. Luster vitreous, dull. Translucent to opaque. (See p. 214.)

With other oxidized copper minerals, sulphides, native copper.

G. 3.9 BROCHANTITE, Cu 56.2%.

4 Struct. — Slender prismatic orthorhombic crystals, striated lengthwise; drusy crusts, fibrous, massive, reniform. (Waringtonite, nonstriated doubly curving wedge-shaped crystals; sp. g. 3.4-3.5). Cleavage distinct, one direction lengthwise (010); brittle; fracture uneven.

Color emerald-green, blackish green. Streak light green. Luster vitreous, pearly. Transparent to translucent. (See p. 216.)

With other oxidized copper minerals, sulphides, native copper.

148 Determinative Mineralogy [Sec. 23

H.

3 G. 3.9-4.0 ALABANDITE (Manganese Glance, Manganese Blende], MnS. 4 Struct. — Granular, compact; isometric-tetrahedral crystals rare. Cleavage distinct, three directions at 90° (100); brittle; fracture uneven.

Color iron-black, tarnish brownish black. Streak olive-green. Luster submetallic, dull. Opaque. (See p. 202.)

In veins with rhodochrosite and metallic sulphides.

G. 3.1-3.3 SCORODITE, FeAsO4-2H2O,

4 Struct. — Pyramidal ortho rhombic crystals, sometimes prismatic or tabular; botryoidal, fibrous, earthy, amorphous. Cleavage imperfect, two directions at 60° and 120° (120); brittle; fracture conchoidal, uneven.

Color pale green, bluish green, blackish green, blue, brown. Streak white, grayish, greenish. Luster vitreous, greasy. Translucent. (See p. 218.)

With arsenopyrite, enargite, limonite, pyrite.

4 G. 3.2-3.3 CROCIDOLITE (Blue Asbestos) approx.

Struct. — Asbestos-like; long delicate flexible fibers, easily separable; compact, earthy.

Color and streak lavender-blue, leek-green; grayish-white (amosite). Luster silky, dull. Opaque. (See p. 222.)

Cross-fiber veins in banded ferruginous shales.

5 G. 3.3-3.4 DIOPTASE (Emerald Copper), H2CuSi04; Cu 40.3%.

Struct. — Small prismatic hexagonal-rhombohedral crystals; crystalline aggregates, crusts. Cleavage distinct, three directions at 54° and 126° (lOll) ; brittle; fracture conchoidal, uneven.

Color emerald-green, dark green. Streak green. Luster vitreous. Transparent to opaque. (See p. 252.)

With other oxidized copper minerals, quartz, limonite.

5 G. 2.4-2.5 LAZURITE (Lapis Lazuli, Native Ultramarine), Struct. — Compact; isometric crystals (dodecahedrons, Fig. 7) rare. Cleavage inconspicuous, six directions at 60°, 90°, and 120° (110); brittle; fracture uneven.

Color azure-blue, violet-blue, greenish blue. Streak pale blue. Luster vitreous. Translucent to opaque. (See p. 230.)

At contacts in crystalline limestone, with pyrite, calcite, pyroxene. Often intimately mixed with calcite, pyrite, muscovite, pyroxene, etc.

5 G. 2.9-3.4 HORNBLENDE (an amphibole), silicate of Ca,Mg,Fe,Al, etc.

6 Struct. — Granular, columnar, fibrous, radiated; long prismatic monoclinic crystals (pseudohexagonal), often with rhombohedron-like terminations; prism angle 124°; some prisms short. Cleavage perfect, two directions lengthwise at 56° and 124° (110); brittle; fracture uneven, splintery.

Sec. 23] Physical Tables 149

H.

Color green, black, brown, gray. Streak brown, green, yellow, gray, white. Luster submetallic, vitreous, silky, pearly. Translucent to opaque. (See pp. 222, 238.)

Common in igneous and metamorphic rocks with feldspars, pyroxenes, chlorite, quartz, calcite.

5 G. 3.2-3.6 PYROXENE, ranging from Diopside,

6 to Hedenbergite, often come Al, Mn, and Na.

AUGITE (a pyroxene), like common pyroxene above, with A12O3 up to 15% or 20%; sometimes alkali metals, Na and K.

Struct. — Granular, columnar, rarely fibrous; lamellar (diallage)', thick monoclinic prisms four- or eight-sided (Figs. 40, 41). Cleavage sometimes distinct, two directions lengthwise at 87° and 93° (110); often prominent parting crosswise (001) ; diallage has fine lamellar parting one direction lengthwise (100); brittle; fracture uneven.

Color bright to dark green, grayish green, black brown. Streak greenish, brownish, grayish to white. Luster vitreous, submetallic, dull. Transparent to opaque. (See pp. 220, 222, 240.)

Common in basic igneous rocks; in crystalline limestones with garnet, chlorite, amphibole, wollastonite, magnetite, pyrite,

5£ G. 9.0-9.7 URANINITE (Pitchblende), UO3, UO2, Pb, Th, La, Y, He, Ra, etc.

Struct. — Botryoidal, granular, lamellar, compact; isometric crystals rare. Cleavage none; brittle; fracture conchoidal.

Color greenish of brownish black, pitch-black. Streak brownish black, grayish black, olive-green. Luster pitch-like, submetallic, dull. Opaque. (See p. 210.)

With ores of silver, lead, copper, bismuth; also in pegmatites.

5£ G. 2.6-2.8 TURQUOIS (Turkis, Turkish Stone), with 6 1.5-6.5% Cu.

Struct. — Compact, reniform, stalactitic, incrusting; thin seams, disseminated; triclinic crystals rare. Cleavage none; brittle; fracture conchoidal.

Color sky-blue, bluish green, apple-green. Streak white, pale green. Luster waxy, dull. Opaque to translucent. (See pp. 250, 256, 260.) Veins and seams in partly decomposed igneous rocks.

6 G. 3.5-3.6 Chloritoid (Ottrelite), H2FeAl2SiO7; some Mg, sometimes Mn.

7 Struct. — Foliated, scaly, rosette groups; rarely tabular triclinic crystals, hexagonal in outline. (Ottrelite, oblong scales). Cleavage perfect, one direction (001); thin flakes brittle.

Color dark gray, greenish gray, greenish black. Streak white, grayish, pale green. Luster pearly, vitreous. Translucent .to opaque. (See pp. 222, 25S, 260.)

In hornfels, slate, schist, with chlorite, hornblende, garnet, corundum.

150 Determinative Mineralogy [Sec. 23

H.

6 G. 4.0-4.5 Gadolinite, FeGYOMSiO; some Ce, La, Nd, Pr, Er, Sc, etc.

7 Struct. — Compact, disseminated, nodular; rough prismatic mono clinic crystals rare. Cleavage none; brittle; fracture conchoidal, splintery.

Color black, greenish black, brown; thin splinters grass-green to olivegreen. Streak greenish gray. Luster vitreous, greasy. Translucent to opaque. (See pp. 232, 252.)

In granite and pegmatite with quartz, mica, allanite, fergusonite, fluorite, molybdenite.

Determination Of Minerals By Means Of Blowpipe And Chemical Tests

Apparatus

Blowpipe. The ordinary jeweler's blowpipe of brass, 10 or 12 inches long, or the cheaper one of japanned iron, serves very well. The more expensive instrument with a platinum tip is more durable (Figs. 59, 60, 61). In any case it is essential that the tip shall be perforated with a very small, smooth hole.

Fig. 59.

Fig. 60.

FIG. 61. Types of Blowpipes.

Lamp. Many types of lamp, or even a candle, may be successfully used with the blowpipe, (a) The ordinary Bunsen gas burner (Fig. 62), or a low form, more convenient for blowpiping (Fig. 63), with a tube to be inserted or slipped over the top. The tube is flattened to a narrow slit at the top and cut off slanting, generally

Determination By Blowpipe Tests

with projecting points left to form a rest for the blowpipe tip. (6) A lamp to use olive oil or other vegetable oil (Fig. 64), or (c) one using tallow, paraffin, or other solid fuel (Fig. 65). The last is most convenient for portable use. It is lighted with a match and the flame is then blown steeply downward for a few seconds in order to melt some of the fuel next to the wick. The heat of the flame then

Fig. 62.

Fig. 63.

FIG. 64. Types of Blowpipe Lamps.

Fig. 65.

keeps it going, (d) Ordinary candles (preferably large and of tallow) serve very well.

Forceps. For most purposes plain iron forceps, 4 or 5 inches long and filed down to small points, are satisfactory. Those with platinum points are better but very expensive (Figs. 66, 67, 68). The points of the " cross-legged " forms close automatically and hold the fragment to be tested. The same result can be attained with the ordinary tweezers by slipping on a loop of small wire after the fragment is in place, as shown in Fig. 66.

Apparatus

Charcoal. Best from soft wood (willow, pine, etc.). Convenient sizes, about J X 1 X4 inches, may be purchased. Used as a support in many operations with the blowpipe (Figs. 75, 76, 81), and in making reductions the carbon assists the flame.

Platinum Wire. A thin platinum wire, 26 B. & S. gage, about 0.4 mm. diameter and 3 inches long, sealed in a small glass tube for a handle (Fig. 79). Most used with a circular loop, f inch (3 mm.) in diameter, at the end to hold a bead of borax, soda, or other flux.

Fig. 66.

Fig. 67.

FIG. 68. Forceps, or Tweezers to be used in Blowpipe Work.

Open and Closed Tubes. To be made of " hard," or " combustion " tubing 4 or 5 mm. internal diameter for closed tubes and 7 or 8 mm. diameter for open tubes. For open tubes cut with a file into 4-inch lengths and use either straight, or better, with a bend near one end (Fig. 78), which may be made by heating until the glass is soft. For closed tubes (Fig. 77), cut into 5-inch lengths, heat the middle in the Bunsen flame or blast lamp, turning slowly in order to heat all sides alike; when soft pull quickly apart. Hold the taper-

FIG. 69. — Hammer and Anvil.

FIG. 70.— Test Tube Holder.

ing part of each tube thus formed in the flame and pull away the slender glass tip.

Hammer. Any small hammer will serve. For the special hammer, a wire handle is best (Fig. 69).

Anvil. Any smooth flat block of iron or steel (Fig. 69). The flat side of a geologist's hammer or prospector's pick is good.

154 Determination By Blowpipe Tests

Magnet. A magnetized knife blade or chisel or a small horseshoe magnet.

Test Tubes. Good sizes are 4Xi and 5 X f inches.

In addition to the above the following articles will be found convenient in the laboratory. For portable outfits they may be dispensed with.

Test Tube Holder. Of brass wire (Fig. 70) or wood — for holding hot tubes.

Streak Plate. Unglazed porcelain; a convenient size is 1JX3 inches. A clean, fine-grained whetstone serves very well.

Blue and Green Glass. Two pieces of each, 2 or 3 inches square, for observing flame colors.

Watch Glasses. Shallow, 2 inches in diameter.

Test Tube Support. Wood, with several holes larger than the tubes. Easily made.

Agate Mortar. 1J inches diameter or larger, with agate pestle. Fragments can be ground under the hammer, and if the anvil is placed in a paper tray of sufficient depth (Fig. 69), the particles that fly will be caught.

Diamond Mortar. Of steel; two-piece form is best. Useful when -only small particles of a mineral are obtainable.

Glass Funnel. Two inches in diameter or larger.

Filter Paper. Round and twice one diameter of the funnel.

Charcoal Brush. For removing sublimates from charcoal an old toothbrush or any stiff brush may be used; or sublimates may be scraped off with a knife.

Plaster Tablets. Thin paste of plaster of Paris is spread about J inch thick on a sheet of glass that has been slightly oiled. While still soft cut the paste with a knife into rectangles about inches. These are readily removed after the plaster hardens. Used for support, like charcoal, and show some sublimates better.

Porcelain Crucible. With support. Sometimes useful for burning a filter paper.

REAGENTS To be used dry :

Sodium Carbonate, or soda, Na2COs; or sodium bicarbonate, common baking soda, NaHCOs.

Sodium Tetraborate, or borax, Na2B40y 10H2O.

Borax Glass may be prepared as required by making borax beads (p. 168) and pulverizing them for use as a flux.

Reagents 155

Sodium Ammonium Phosphate, also called " phosphorus salt " and " microcosmic salt," HNaNH4PO4-4H2O. Loses NH4OH and 4H20 on heating, becoming sodium metaphosphate (NaPOs), abbreviated s.ph.

Test Papers, small strips of blue and red litmus paper and yellow turmeric paper.

Occasional use will also be found for the following:

Potassium Bisulphate, KHSO4.

Turner's Flux, 1 part finely powdered fluorite (CaF2) with 3 parts potassium bisulphate (KHS04).

Von Kobell's Flux, 1 part potassium iodide (KI), 2 parts sulphur (S), and 1 part potassium bisulphate (KHS04).

Tin, foil or granulated. Scraps of tin cans or other tin plate will serve. Also Zinc, either granulated or scraps of sheet metal; Potassium Nitrate, KNO3; and powdered Galena, PbS, Gypsum, CaSO4-2H2O, and Fluorite, CaF2.

To be used in liquid form :

Water, H2O, distilled or rain water is best; for most purposes any clear water that is not " hard " will serve.

Hydrochloric Acid, HC1 (" muriatic acid "), for most purposes the concentrated acid as obtained from the supply houses (sp. gr. 1.20) is diluted with an equal quantity of water, giving a solution a little stronger than 5/N.

Other mineral acids are more dangerous to handle and less useful than hydrochloric. Many of the reagents that follow are rarely needed ; on the other hand, most of those used in a chemical laboratory will occasionally be found useful.

Nitric Acid, HNOs (" aqua fortis "). To dilute the concentrated acid (sp. gr. 1.42) to approximately 5/N, add two volumes of water.

Nitrohydrochloric Acid (" aqua regia "), 3 parts hydrochloric and 1 part nitric acid.

Sulphuric Add, H2SO4 (" oil of vitriol "). In diluting add the concentrated acid (sp. gr. 1.84) very slowly to 6 volumes of water, for approximately 5/N.

Ammonium Hydroxide, or ammonia, NH4OH. Add to the concentrated solution (sp. gr. .90) three volumes of water, for approximately 5/N. This solution will neutralize an equal volume of the dilute acids.

156 Determination By Blowpipe Tests

Potassium Hydroxide, KOH (" caustic potash "). Best kept as sticks broken to short bits and placed in a well-stoppered bottle — to be dissolved in a little water as needed.

Ammonium Molybdate, (NHMoOd. Dissolve the crystals in water that has been made alkaline with ammonia. For use acidify a little of this solution in a test tube with HNOs; the ppt. that forms is quickly cleared up by further addition of acid.

Cobalt Nitrate, Dissolve the crystals in 10 parts of water. A dropping bottle holding one or two ounces is convenient for laboratory use.

Ammonium Carbonate, (NHCOa. Dissolve in water as needed.

Ammonium Oxalate, Dissolve in water as needed.

Sodium Phosphate, Na2HP04. Dissolve in water.

Barium Chloride, BaCb. Dissolve in water.

Barium Hydroxide, Dissolve in water.

Silver Nitrate, AgNOs. Dissolve in water and keep in a bottle of amber color or one well wrapped with opaque paper.

Potassium Ferrocyanide, Dissolve in water.

Potassium Ferricyanide, Dissolve a little at a time in water as needed. The solution does not keep well.

Hydrogen Peroxide, The ordinary 3% solution serves. Keep in bottle of amber color or one wrapped in opaque paper.

Stannous Chloride, SnC, when required, may be prepared by treating tin foil with HC1.

Dimethylglyoxime, C4HgO2N2. Dissolve in 100 tunes its weight of alcohol. Useful in testing for Ni.

Blowpipe Operations And Chemical Tests

Blast. The blast of the blowpipe should not be blown from the lungs and should not interfere with regular breathing. Distend the cheeks fully and, while breathing through the nose, allow the air to escape from the mouth through the blowpipe without making any effort to blow. Before the supply is exhausted distend the cheeks again from the lungs. In this way the blast may be continued for several minutes, when necessary, without fatigue. If the blowpipe tip is in good condition the flame will be smooth, steady, and silent (Figs. 72-76).

Flames. A candle flame or luminous gas flame consists of 3 concentric parts (Fig. 71): (a) an inner cone of unburned gases; (6) a

Blowpipe Operations And Chemical Tests

mantle of unburnod gas or vapor, full of glowing particles of carbon, where carbon monoxide (CO) and water (HO) are forming by combustion; (c) a hot, non-luminous mantle of the products of complete combustion, carbon dioxide (CO2) and water (H2O) mingling with the surrounding air, and hence with an excess of oxygen. Hot fuel is in excess in (6), hence it is reducing in its action; but the temperature is too low for vigorous reduction. The excess of oxygen makes (c) oxidizing, and it is also hotter. A non-luminous Bunsen or alcohol flame differs only in lacking the incandescent carbon in (6).

Fig. 71.

Fig. 72.

FIG. 71. — Candle flame: (a) Unburned gases; (6) burning gases, forming H2O, CO, and luminous C; (c) hot combustion products, H2O, CO2 mingled with O from surrounding air. The luminous gas flame is the same.

FIG. 72. — Blowpipe flame: (a) Mixture of unburned gas and air from the blowpipe; (6) burning gas gives intense heat and slight reducing action j (c) and beyond, hot combustion products with excess of O from the air — oxidizing flame (o.f.). A candle or kerosene flame may be used in the absence of gas or alcohol.

In determinative mineralogy these flames are often directed laterally or inclined downward by the use of the blowpipe. For oxidizing effects the tip should be inserted slightly into the flame, as in Fig. 72, thereby mixing more oxygen with the gases at the base. The best reducing effect is obtained by withdrawing the tip a little from the flame and blowing very gently (Fig. 73). The flame should not be sooty, but a little luminous carbon should extend down the whole length of it.

Ignition: Fusion. The application of intense heat is commonly called ignition. The hottest flame is entirely non-luminous and the hottest part of it is just beyond the visible blue tip. The fusibility of a mineral is tested at this point by strongly heating an elongated

Determination By Blowpipe Tests

fragment not more than 1.5 mm. of an inch) in thickness; that is, thinner than the " lead " of an ordinary pencil. This is held in the forceps so that it projects into the flame (Fig. 74). The mineral may fuse quietly, or with intumescence (bubbling and swelling up),

FIG. 73. — Blowpipe flame: (6) Strong reducing flame (r.f.), with gentle blast and more gas than used in o.f.

or with exfoliation (splitting into leaves or flakes). The result may be fusion to a bead of colored or colorless glass, clear or filled with bubbles; or to a white, opaque enamel. If infusible the mineral may remain unchanged, or it may change color, or become opaque, etc. All of these properties should be carefully noted.

FIG. 74. — Testing fusibility, showing maximum size of fragment, manner of holding it, and position in the flame.

Decrepitation. The violent breaking away of particles with little crackling explosions' owing to sudden unequal heating or to the expansion of minute inclusions of water or liquid carbon dioxide is called decrepitation. This sometimes interferes seriously with the determination of fusibility. By first heating the mineral very gradually and gently in the Bunsen flame this difficulty may sometimes be avoided; otherwise heat a few fragments in a closed tube until decrepitation ceases ,a:id select a fragment of suitable size, if

Blowpipe Operations And Chemical Tests 159

such remains. When this fails, make a thin paste of the finely powdered mineral with water, spread a little of this on charcoal and heat, at first very gently, then intensely. The crust thus formed can be taken up carefully in the forceps and tested for fusibility.

Scale of Fusibility. The degree of fusibility of minerals is indicated by numbers referring to the following scale. Comparison should be made on fragments of about the same size. Penfield recommends a standard size of about 1.5 mm. in diameter, as explained above. With the more difficultly fusible minerals, however, a much smaller fragment with a very thin edge or fine point should be tested before deciding that it is infusible.

SCALE OF FUSIBILITY (Penfield's modification of von Kobell's scale)

(Minerals named in parentheses have about the same fusibility as the standard.)

1. Stibnite, Sb2Ss. Fragments larger than standard size fuse easily

in a luminous flame; fuses easily krclosed tube below red heat. (Realgar, orpiment, sulphur.) /

2. Chalcopyrite, CuFeS2. Standard size fragment fuses in luminous

flame; small fragment fuses in closed tube at red heat. (Galena,

arsenopyrite, apophyllite.)

3. Almandite (Garnet), Fes A12 Standard fragment fuses

readily to globule with blowpipe ; only thinnest edges rounded in luminous flame. (Malachite, wernerite, stilbite.)

4. Actinolite, Edges easilyrounded on stand-

ard fragment; fine splinter fuses easily to globule. (Tremolite, wollastonite, barite.)

5. Orthodase, KAlSiaOg. Edges of standard fragment rounded with difficulty; only finest splinters fuse to globule. (Sphalerite, biotite, scheelite.)

6. Bronzite, Only finest points and thinnest edges can be rounded at all. (Enstatite, calamine, serpentine.)

Quartz may be added as No. 7 to represent minerals that are

infusible in the blowpipe flame.

160 Determination By Blowpipe Tests

Flame Colors. Some minerals on ignition impart to the blowpipe flame a distinct color, which is best seen against a dark background. It is often more distinct when a trace of fine powder is introduced into the Bunsen flame with a clean, dry platinum wire. Hold the wire first in the cool edge of the flame, at the base, then raise it gradually into the hottest central part near the tip. If the wire is first moistened with water a larger quantity will adhere, and this is sometimes advantageous. Instead of water dilute HC1 is often helpful, and with some minerals concentrated

Absorption-light filters are useful in analyzing mixed flames. Blue and green glass are commonly used for this purpose, but the Merwin flame-color screen is more effective. It consists of strips of transparent blue and violet celluloid that are partly overlapped, forming three color divisions. In use the glass or screen is held close to the eyes and the colored flame viewed through it. The colors imparted by various substances and the effects of absorptionfilters are given in the table on the opposite page.

Roasting on Charcoal. Spread a fine powder of the mineral thinly on charcoal and heat with a small oxidizing flame, a considerable distance beyond the tip of the blue and at no more than a dull red heat (Fig. 75). If the mineral fuses easily heat intensely till the

FIG. 75.— Roasting on charcoal; use very small o.f., scarcely red heat, to oxidize S, As, Sb and to drive off volatile constituents.

volatile constituents are driven off, then pulverize with a little powdered charcoal and repeat the roasting with the mixture, using the small oxidizing flame and low temperature again.

Ignition on Charcoal. With the edge of a small coin make a slight depression near one end of the coal and place in it a few grains of the mineral, not larger than pin heads. Hold the length of the coal in line with the flame and tilted towards it (Fig. 76), in order to catch any sublimate that may form.

First heat for only 2 or 3 seconds with a small gentle oxidizing flame, as in roasting (Fig. 75), not allowing the visible flame to come

Blowpipe Operations And Chemical Tests

Flame Colors

(For abbreviations, see page 285) (Merwin screen : 1. Blue; 2. Overlap; 3. Violet)

Color.

Shade.

Substance. , Absorption-effects. Remarks.

Red

Crimson

Sr

1, 2, Invisible; 3. Crimson. Faint yellow through green glass. Alk. after ign. Sr sol. with few drops BaCl2 sol. gives red flame after green.

Red

Crimson

1, 2. Invisible; 3. Crimson. Invisible through green glass. Not alk. after ign. Li sol. with few drops BaCl2 sol. gives red flame before green.

Red

Yellowish to orange

Ca

1. Gnh. yel.; 2. Faint grn.; 3. Pale crimson. Invisible through green glass. Improved by HC1. Alk. after ign.

Yellow

Intense

Na

Intense and persistent. 1, 2, 3. Invisible. Invisible through blue glass.

Green

Yellowish

Ba

1. Green; 2, 3, Pale green. Alk. after ign.

Green

Yellowish

B

1. Green; 2, 3. Pale green. Use cone. H2SO4; for insol. minerals use 3 parts Turner's flux. (Turmeric test decisive.)

Green

Yellowish

1. Emerald; 2. Pale bluish green; 3. Pale lavender.

Green

Pale yem.

Mo

From oxide or sulphide. ,

Green

Emerald

CuO Cul

With HC1 blue flame tinged with green.

Green

Pale

Te

Sb

Green

Pale bluish

P

1. Grn.; 2. Pale grn.; 3. Light violet-red. Use cone. H2SO4.

Green

Bluish

Zn

Bright streaks in outer part of flame.

Blue

Azure

Outer fringe of emerald green. 1. Bright grn.; 2. Pale grn.; 3. Blue, with green fringe.

Blue

Indigo

Se

Characteristic radish-like odor.

Blue

Pale azure

Pb

Green tinge in outer part of flame.

Blue

Pale

As

Characteristic garlic odor.

Violet

Pale

K

1. Blue-violet; 2. Faint violet-red; 3. Reddish-violet. Purplish-red through blue glass.

162 Determination By Blowpipe Tests

near the mineral. Note reactions, if any: (1) decrepitation, (2) deflagration, (3) visible fumes. The moment the heat is stopped seek for (4) odors, and observe (5) any change in color and (6) color and position of sublimate, if any. (Caution: Do not mistake ash for sublimate.) If the mineral blackens, test when cold for (7) magnetism. Repeat the oxidizing flame with increasing intensity, using fresh material if necessary, until the reactions are clearly determined. Next use the reducing flame (Fig. 76) on the oxidized material; beginning gently and increasing the intensity. Look for

FIG. 76. — Reduction on charcoal, with sublimates, when formed, at (d) and beyond. For comparison burn a spot on the coal and observe the color and texture of the ash. Note that the grain shows distinctly in the ash, while sublimates tend to conceal it.

the above reactions and also (8) globules of metal that may be reduced. If the reactions are weak and uncertain mix the powdered mineral with three times its volume of soda and a little borax and charcoal powder, then fuse on charcoal for a full minute with the most intense heat.

Reduction of Metals. Mix equal volumes of finely powdered mineral,* charcoal, and borax with 3 volumes of soda. Moisten slightly with water and place a mass the size of a small pea in a shallow depression on the charcoal. Fuse in a strong reducing flame for two or three minutes without interruption, unless a bead of metal becomes distinctly visible in a shorter time. If no metal is visible pry off the assay with a chisel or knife, removing with it a little of the charcoal on which it rests; grind to a fine powder in an agate mortar, and while continuing the grinding, allow water to flow gently from the tap upon the hand and into the mortar. The surplus soda dis-

If the mineral yields S, As, or Sb in o.f. on charcoal, it must first be thoroughly roasted in order to convert it into oxides. (See p. 160.)

Blowpipe Operations And Chemical Tests

Sublimates On Charcoal

(For abbreviations, see page 285)

Near Assay.

Dist. from Assay.

Substance.

Remarks.

White, very volatile

White to grayish

As203

Mostly far from assay; often strong garlic odor

Dense white, volatile

Gray or slightly brownish

White, Te02 Gray, Te

Volatilizes in r.f., coloring flame pale green

Dense white, volatile

Bluish

Sb2O3 and SbSbO4

Heavy near the assay

White

White to bluish

Chlorides of Cu, Pb, Hg, NH4, and alkalis

Pale yel. to wh. hot; wh. cold; non-vol. in o.f .

Faint white

SnO2

Moistened with and ignited, subl. becomes bluishgreen

Pale yel. hot; wh. cold; vol. in o.f.

Bluish

MoO3

Touched with r.f., subl. becomes azure-blue. Cu-red MoO2 subl. next to assay

Canary-yel. hot ; wh. cold; nonvol. in o.f.

Faint white (See p. 189)

ZnO

Moistened with and ignited the subl. becomes green

Yel. hot; pale yel. cold; vol. in o.f. and r.f.

Dense white with bluishwh. border

PbO PbS03 PbSO4

Forms when galena and other Pb sulphides are heated very hot on charcoal

Dark yel. hot; S-yel. cold; vol. in o.f. and r.f.

Bluish-white

PbO

Heated with von Kobell's flux forms volatile yelh.-grn. subl., PbI2

Dark orange-yel. hot; orange-yel. cold; vol. in o.f. and r.f.

Greenish-white

Bi203

Fused with von Kobell's flux in small o.f. forms yel. subl. fringed by brilliant red

Nearly blk. to rdh.-brn.; vol. hi o.f. and r.f.

Yellow

CdO

Iridescent when very thin

Rdh. to deep lilac

Ag with Pb and Sb

Ag alone gives slight bnh. subl. after long ignition

Copper-red

White

MoO2 MoO3

Touched with r.f., white subl. becomes azure-blue

Steel-gray, faint metallic luster; very vol.

WThite; may be tinged red

White, SeO2 Red, Se

Subl. colors r.f. azure-blue. Characteristic radish-like odor

Determination By Blowpipe Tests

solves and the powdered charcoal is floated away by the overflow. Globules of metal, flattened by the grinding, will appear as bright scales on the pestle and in the mortar. . (See Fig. 76.)

Transfer the metal to a watch glass, add a drop or two of HNOs, warm gently and add an equal amount of water.

White Metal Sn changes to white insoluble oxide; Pb soluble and gives white precipitate with a drop of HSCU ; Ag soluble and gives with a drop of HC1 a white precipitate which is soluble in ammonia; Pt insoluble in HNOs, soluble in aqua regia. Evaporate to dryness, add water and KC1, a yellow precipitate confirms Pt.

Yellow or Red Metal. Cu soluble in HNOs and gives reddishbrown precipitate with potass, ferrocyanide; Au insoluble in HNOs, soluble in aqua regia. Evaporate to dryness, add a drop or two of water and a drop of dilute solution of SnCb. A violet-brown precipitate confirms Au,

Iodide Sublimates On Plaster And Charcoal

(For abbreviations, see page 285)

On Plaster.

Substance.

On Charcoal.

Chrome-yellow, volatile

PbI2

Chrome-yel.; gnh. if thin; volatile

Yellow to orange; very volatile

AsI3

Faint yellow

Orange to red; disappears in strong ammonia fumes

Sbli

Faint yellow

Scarlet with yel.; if strongly heated is dull yel. and blk.

Hgl

Faint yellow

Rdh.-brn., nearly scarlet

SeI4

Does not show on charcoal

Chocolate-brn., with underlying scarlet; in ammonia fumes becomes orange and then cherry-red

BiI3

Bright red; yellow near assay

Purplish-brn., darker border

TeI4

Does not show on charcoal

Ultramarine-blue, deep

MoI4

Does not show on charcoal

On Plaster Tablets. The tablet may be placed on charcoal as a support. A little of the pulverized mineral is mixed with von Kobell's

Blowpipe Operations And Chemical Tests

flux and fused near one end of the tablet. Volatile iodides are formed, many of which produce characteristic sublimates on the cool part of the plaster. The same process may be used on charcoal, and in the accompanying table the results are compared with those on plaster.

FIG. 77. — Heating in closed tube (c.t.): Hold the tube with the fingers only, and hold it in nearly horizontal position.

FIG. 78. — Heating in open tube (o.t.): Use tube holder and allow part of the flame to play up the steeply inclined arm of the tube, in order to insure a sufficient draft, or blow into the lower end with the blowpipe.

In Closed Tube. The object is to heat the mineral with little air, and hence with little oxidation. Use small fragments; fine powder adheres to the side of the tube and may interfere with sublimates. Volatile emanations that give an odor or condense as a sublimate or a liquid on the side of the tube are to be specially noted ; also decrepitation, phosphorescence, fusion, change in form or color, or mag-

Determination By Blowpipe Tests

netism. The upper end of the tube must be kept cool, and this is best assured by holding it with the fingers only and keeping it nearly horizontal (Fig. 77).

Sublimates In Closed Tube

(For abbreviations, see page 285)

Hot.

Cold.

Substance.

Remarks.

Colorless liquid; easily volatile

Cols, liquid

H2O

Neutral or acid; rarely alkaline

White solid

White solid

PbCl2, SbCl3, As203, Sb203, NH4 salts

Gray metallic liquid globules

Hg

Unite by rubbing with strip of paper

Pale yel. to cols, liquid; difficultly volatile

Cols, to wh. globules

TeO2

From Te and some compounds

Dark yellow to red liquid; easily volatile

Yel. xln. solid; pale in small amount

S

From S and some sulphides

Dark red liquid, nearly blk.; easily volatile

Rdh.-yel. transparent solid

AsS As2S3

From sulphides and sulpharsenites

Black solid; difficulty volatilized

Rdh.-brown

Sb2OS2

Sulphides and sulphantimonites

Brilliant blk., solid; often gry. and xln. near heated end

As

From As and arsenides. Break off closed end and heat subl. for garlic odor

Brilliant blk,. solid

HgS

Subl. rubbed gives red powder

Blk. fusible globules

Te

Te and tellurides; usually some TeO2 formed (see above)

Blk. fusible globules; smallest deep red by transmitted light

Se

Often also wh. xln. SeO2

In Open Tube. The object is to heat the mineral with a good supply of air for oxidation. Place finely powdered mineral near one

Blowpipe Operations And Chemical Tests

end of the tube (at the elbow if the tube; is bent). Hold the tube steeply inclined, with the powder at the lower end, using a holder, since the whole tube must become hot. An edge of the flame should play constantly (or very frequently) on the upright portion of the tube in order to insure an active draft. This may be facilitated also by blowing into the lower end of the tube with the blowpipe. Use but little of the mineral, in order to avoid choking the tube and reducing the draft; also, with a large amount, volatilization may exceed oxidation and the results will be mixed and indecisive. (See Fig. 78.) Observe odors, visible fumes, and sublimates.

Sublimates In Open Tube

(For abbreviations, see page 285)

Color and Character.

Substance.

Remarks.

White xln., readily volatile

As2O3

Xln. (octahedrons) on the warm glass

White xln., readily volatile

Se02

Usually radiating xls. ; often a little red Se

White xln., slowly volatile

Sb2O3

Xls. are octahedrons and prisms

White non-vol., infusible

Slight deposit; mostly on lower side of tube near assay

Pale yel. globules; slowly vol.

TeO2

Globules white or colorless when' cold

Pale yel. hot; wh. cold; amorph., infus., non-vol

Dense wh. smoke; subl. mostly on under side of tube; usually some volatile Sb2O3

Pale yel. hot; wh. cold; fus. and vol. at red heat

MoO3

Network of delicate xls. near assay

Yel. to orange; easily vol.

S,AsS

These sublimates result from too rapid heating; will not form with proper draft and oxidation. Heat tube above assay first, then directly under it

Blk. hot; brn. cold; dif. volatile

Sb2OS2

Brilliant blk.; volatile

As,HgS

Gry. metallic globules; volatile

Hg

Unite by rubbing with strip of paper

Red, volatile

Se

Often with white SeO2 (see above)

Determination By Blowpipe Tests

In Borax Bead. A round loop inch diameter) of platinum wire may be made conveniently by bending it around the tapering part of a pencil near the point (Fig. 79a). The loop is heated in the Bunsen or blowpipe flame and dipped into the powdered borax. The part that adheres is fused to a clear globule (Fig. 80); this is again dipped into the borax, and the process is repeated until a spherical bead is obtained. The hot bead is touched lightly to a fine powder of the mineral and is then heated thoroughly in the oxidizing blowpipe flame, f The degree of solubility of the particles and the colors, if any, imparted to the bead are carefully noted. It is then heated continuously for some time in the reducing flame, and any change noted. The quantity of the powdered mineral in the bead is gradually increased until a distinct reaction is obtained or until the bead is saturated with it.

A bead about half the size described above may be made on the end of the wire without a loop by holding it horizontally or pointed somewhat downward in the flame. Moisten the bead with the tongue and touch the finely powdered mineral. After reducing, cool the bead in the inner cone of the Bunsen flame in order to avoid oxidation.

In Sodium Metaphosphate Bead. The

bead is made by heating sodium ammonium phosphate on a loop of platinum wire in the same manner as previously described for the borax bead; but when first fused it is much more liquid than borax and the greatest care must be exercised in order to avoid dropping it. It is best to tilt the burner at a considerable angle (Fig. 80), so that beads cannot drop into it and clog it. Hold the wire over the center of the flame, with the circular loop horizontal. Do not undertake to fuse much of the salt at a time, but build up the bead by small additions, heating each time until all bubbling stops. The salt fuses to sodium metaphor-

Sulphides, arsenides, antimonides, etc., must first be roasted thoroughly at a dull red heat (Fig. 75), in order to convert them into oxides; otherwise no characteristic reaction will occur.

t A minute grain of KNO3 added to the hot bead after the mineral is dissolved gives instant oxidation.

FIG. 79 — Platinum wire loops : (a) single loop inch, for bead tests; (6) double loop, holding larger quantity, for decomposing insoluble minerals in fluxes.

Blowpipe Operations And Chemical Tests

Borax Bead Reactions

(For abbreviations, see page 285) (M indicates medium amount; + indicates much; — indicates little)

Oxidizing Flame.

Reducing Flame.

Amount.

Oxide" of

Hot.

Cold.

frot.

Cold.

Colorless

Colorless

Colorless

Colorless

+ or -

Si, Al, Sn

Colorless

Cols, or opaq. wh.

Colorless

Cols, or opaque wh.

+ or -

Ca, Sr, Ba, Mg, Zn, Zr, Cb

Pale yel.

Cols, or wh.

Pale yel

Colorless

+

Pb, Sb, Cd

Pale yel.

Cols, or wh.

Gray

Gray

+

Bi

Pale yel.

Cols, or wh.

Brown

Brown

+

Mo

Pale yel.

Cols, or wh.

Yellow

Yel. to yelhbrn.

M

W

Pale yel.

Cols, or wh.

Grayish

Bnh. -violet

M

Ti

Yellow

Nearly cols.

Pale green

Nearly cols.

Fe, U

Yellow

Yelh.-green

Green

Green

Cr

Yellow

Pale yelh.- grn.

Dirty grn.

Fine green

—

Yel. to orange

Yellow

Pale green

Pale grn. to nearly cols.

Mto +

U

Yel. to orange

Yellow

Bottle grn.

Pale green

Mto +

Fe

Yel. to orange

Yelh.-grn.

Green

Green

Mto +

Cr

Green

Blue

Cols, to grn.

Opaq. red

(+)

- toM

Cu

Blue

Blue

Blue

Blue

- to M

Co

Violet

Rdh.-brn.

Opaque gray

Opaque gray

- toM

Ni

Violet

Rdh. -violet

Colorless

Colorless

Mn

170 Determination By Blowpipe Tests

phate, NaPOs, and is used in exactly the same manner as the borax bead.

In Sodium Carbonate (Soda) Bead. The soda bead on platinum wire is opaque white when cold. It is prepared in the same manner as borax or s.ph. beads (see preceding sections), and is useful for th'e following reactions:

Manganese : in o.f., green when hot," blue when cold; in r.f., colorless.

Chromium: in o.f., yellow.

Quartz, chalcedony, or opal: in fine powder fused with about equal volume of soda gives vigorous effervescence of and forms a clear glass.

FIG. 80. — Making a bead in the Bunsen flame. If the bead drops it falls clear of the burner instead of clogging it. This position is specially important for sodium metaphosphate (s.ph.) beads. A metal tray should be so placed as to catch the fused fluxes that drop.

With Acids. For most purposes dilute hydrochloric acid is used; but for sulphides and arsenides, which require oxidation, nitric acid is best.

Usually the object of the first test with an acid is to determine whether or not the mineral is decomposed or dissolved by it. This is best done as follows:

(1) Using the small blade of a knife (say less than one-fourth inch wide) for a spatula, put into the test tube as much of the finely pulverized mineral (not lumps or grains) as will lie on one-half inch of the tapering point. Pure homogeneous material should be used, or allowance made for any known impurity.

Blowpipe Operations And Chemical Tests

Sodium Metaphosphate Bead Reactions

(For abbreviations, see page 285) (M indicates medium amount; + indicates much; —indicates little)

Oxidizing Flame.

Reducing Flame.

Amount.

Oxide of

Hot.

Cold.

Hot.

Cold.

Colorless

Cols, or opaq. white

Colorless

Cols, or opaq. white

-or +

Ca, Sr, Ba, Mg, Zn, Al, Zr,

Sn, Si (Si nearly insol.)

Pale yel.

Colorless

Pale yel.

Colorless

+

Cd

Pale yel.

Colorless

Gray

Gray

+

Pb, Sb, Bi

Pale yel.

Colorless

Brown

Brown

+

Cb

Pale yel.

Colorless

Dirty blue

Fine blue

M

W

Pale yel.

Colorless

Yellow

Violet

- to -f-

Ti

Yellow

Colorless

Pale yelh.- grn.

Colorless

—

Fe

Yellow

Pale .-

yel.

Pale grn.

Fine grn.

M

U

Yelh.-grn.

Colorless

Dirty grn.

Fine grn.

M

Mo

Yel. to bnh.-red

Yel. to cols.

Red, yel., to yelh.-grn.

Nearly cols, to pale violet

Mto +

Fe

Yel. to deep yel.

Yellow

Dirty grn.

Fine grn.

-toM

Red to bnh.-red

Yel. to redh.-yel.

Red to bnh.-red

Yel to redh.-yel.

- toM

Ni

Green

Pale blue

Pale yelh.- grn.

Pale blue, nearly cols. ; at times ruby red

Cu

Dark green

Blue

Bnh.-grn.

Opaq. red

M

Cu

Dirty grn.

Fine grn.

Dirty grn.

Fine grn.

- toM

Cr

Blue

Blue

Blue

Blue

- to M

Co

Gryh.-violet

Violet

Colorless

Colorless

M

Mn

172 Determination By Blowpipe Tests

(2) Add acid (dilute HC1 unless otherwise specified) to a depth of one-half to three-quarters of an inch.

(3) Shake up the powder in the acid and note carefully its behavior —how much it roils the liquid and how slowly or rapidly it settles out and clears.

(4) If no immediate reaction occurs in the cold acid, heat to the boiling point over the Bunsen flame and note any change, particularly whether any of the mineral powder has disappeared.

(5) If the mineral seems unchanged continue the boiling until two-thirds of the acid has been evaporated.

(6) If the result still seems to be negative, filter the acid into a clean test tube and evaporate to dryness. The residue, if any, is the measure of the reaction that has taken place.

(7) If solution or other reaction occurs the results should be carefully noted, as follows :

(a) Solution with effervescence in cold acid, or only on heating (and this point should be carefully observed), with the evolution of C02, colorless and odorless, from carbonates (test with on glass rod) ; H2S, colorless and disagreeable odor, from some sulphides; Cl, nearly colorless, pungent odor (bleaches moist litmus paper), from some higher oxides in HC1; NCb, dark red vapors, from oxidation of sulphides, etc., in HNOs.

(6) Solution without effervescence, giving a clear colorless solution, without residue. When slow this reaction is sometimes difficult to detect. Filtration and evaporation to dryness may fee resorted to in case of doubt, or a drop of perfectly clear liquid, after settling, may be removed with a pipette and evaporated on a watch glass, a piece of platinum foil, or a flake of mica. A residue shows that some solution has taken place.

(c) Solution may occur without effervescence and without residue, as described in the preceding paragraph, but with a colored solution — yellowish to brownish red from ferric iron minerals in HC1; green from nickel and from mixtures of copper and iron (add ammonia and the solution becomes blue with copper or nickel, more intense with copper) ; blue from copper minerals, intensified by the addition of an excess of ammonia; pink or pale rose from cobalt minerals.

(d) Solution may occur without effervescence, leaving an insoluble residue — gelatinous silica, from some silicates, appears on evapora-

An alcohol lamp is a good substitute, and an ordinary kerosene lamp serves very well if the tube is held in the top of the chimney. A test tube may be even heated over a candle flame by holding it just high enough to avoid blackening it with soot.

Blowpipe Operations And Chemical Tests 173

tion of the acid and remains insoluble when diluted with water or more acid ; powdery or flaky silica separates from some silicates — it is white and more translucent than the fine powder of the mineral; white opaque metallic oxides, especially from tin, antimony, and lead minerals in HNOs; yellow powder, WOs, from some tungstates in HC1; yellow floating mass of sulphur, often black with particles of the mineral, from many sulphides in HNOs.

With Cobalt Nitrate. The solution is useful with light-colored infusible minerals. Heat a small amount of the fine powder or minute fragments intensely on charcoal in the oxidizing flame; moisten the mineral with the solution, and again ignite to an intense white heat. Distinct colors may be imparted, as follows:

Blue, aluminum minerals, zinc silicates.

Bluish green, tin oxide. Yellowish green, zinc and titanium oxides.

Dark green, oxides of antimony and cobalt.

Pink, usually pale, from magnesium minerals.

Calcite and aragonite are readily distinguished by reaction with Co (N Os) 2 solution. Place fine powder of calcite and the mineral to be tested in separate test tubes, fill each about one-half inch deep with the solution, and boil both together by holding the tubes side by side over the Bunsen flame. Aragonite is colored a deep lavender by CoCOs while calcite remains white, except on long continued boiling.

Precipitates from Solution. The following reagents are most commonly used. For distinctions between the various precipitates, see the tests for the elements on succeeding pages.

Ammonia precipitates hydroxides of Al, Gl, Bi, chromic Cr, Fe, Pb, Ti, and rare earth metals. (In the presence of phosphoric, arsenic, silicic, and hydrofluoric acids various other substances are also precipitated.)

Ammonium carbonate and ammonium oxalate precipitate Ca, Sr, and Ba from solutions made alkaline with ammonia.

Ammonium sulphide precipitates from neutral or alkaline solutions sulphides of Fe, Zn, Mn, Co, Nit and hydroxides of Al, Cr, and rare earth metals.

Barium chloride precipitates BaSCU from acid solutions of a sulphate— a delicate test.

Hydrochloric acid precipitates chlorides of Ag, Pb, and mercurous Hg from solutions in HNOs.

Silver nitrate precipitates silver chloride, bromide, or iodide from solutions of the corresponding minerals in water or HNOs.

174 Determination By Blowpipe Tests

Sodium phosphate precipitates Mg from solutions in which ammonia and ammonium carbonate give no precipitates or in the filtrate after precipitating with these reagents.

Sulphuric acid precipitates sulphates of Pb, Ba, and Sr, and also Ca in concentrated solutions.

Reactions For The Elements

(For list of elements, see page 286, abbreviations, page 285)

ALUMINUM (Al; trivalent; at.wt. 27.1)

(1) Color with Cobalt Nitrate. Fine powder of light-colored infus. Al minerals assume a fine blue color when moistened with the solution and intensely heated either on ch. or in a small loop of Pt wire. Zn silicates also give blue color, but will yield test for Zn.

(2) Precipitation with Ammonia. Added in slight excess to acid solutions, gelatinous is precipitated. To distinguish from other similar-looking precipitates obtained in the same way, filter, wash the ppt., place part of it in test tube with EkO and KOH; if it is it will go easily into solution. Burn the filter (in crucible or on ch.) and the rest of the ppt. will give foregoing test with cobalt nitrate.

For Al in silicates, see Silicon (2), page 185.

ANTIMONY (Sb; trivalent and pentavalent; at.wt. 120.2)

(1) Oxide Subl. on ch. Heat fragments on ch. in o.f. A dense white subl. of Sb2Os forms very near the assay (compare As). Where thin the coating looks bluish. Subl. is volatile and may be driven about readily by the o.f. or r.f. No distinctive odor (compare As) unless S or As is present.

(2) Antimonate Subl. in o.t. When heated in o.t. most Sb sulphides yield a heavy white subl., SbSbCU, along the under side of the tube, which is non-vol. (compare As), straw-yel. when hot and white on cooling.

(3) Oxysulphide Subl. in c.t. On intense ign. sulphides yield a black subl. of Sb2S20, rich redh.-brn. on cooling. Volatilizes with difficulty.

(4) Iodide Subl. on Plaster. Mixed with von KobelPs flux or moistened with HI and heated in o.f. on plaster tablet, a red subl. of , which disappears in fumes of strong ammonia.

Reactions For The Elements 175

(5) Flame Color. Sb volatilizes in r.f. and gives a pale greenish color to the flame. Pt forceps must not be used.

ARSENIC (As; trivalent and pentavalent; at.wt. 75)

(1) Oxide Subl. on ch. Metallic As, its sulphides and the arsenides when heated on ch. yield white fumes of a garlic-like odor and a white crystalline subl. of As20s far from the assay.

(2) Oxide Subl. in o.t. Subl. and odor like preceding are produced in the tube. Easily volatile and driven out of the tube.

(3) Metallic Mirror in c.t. The metal and some arsenides yield a brilliant black arsenical mirror. When abundant the part nearest the assay crystallizes and looks gray. By breaking off the closed end of tube and heating the subl. the garlic odor is produced. Oxygen compounds require powdered charcoal also in the c.t.

(4) Iodide Subl. on Plaster. Powder mixed with von KobelPs flux or moistened with HI and heated in o.f. on plaster tablet, a vol. orange-yel. subl. of Asls forms.

(5) Flame Color. In r.f. As volatilizes and colors the flame violet.

BARIUM (Ba; bivalent; at.wt. 137.4)

(1) Flame Color. A gnh.-yel. color is imparted to the flame, sometimes intensified by moistening with HC1. Silicates do not give the flame color. Must be distinguished carefully from B,' MnCk, and P flame colors.

(2) Sulphate Precipitate. A few drops of dilute H2S04 give a white ppt. of BaSO4 from solutions in water and dilute acids. A delicate test and distinguishes from B and P. Insoluble silicates require previous fusion of the finely powdered mineral with 3 volumes of soda in a loop of Pt wire, which renders them soluble in HC1. Test ppt. for flame color using clean Pt wire. If both Ba and Sr are present a mixed flame results.

(3) Alkaline Reaction. Like the other alkaline earths and most alkalis, some Ba minerals give alkaline reaction on moist turmeric paper after ignition.

BISMUTH (Bi; trivalent; at.wt. 208)

(1) Metallic Bi and Oxide Subl. on ch. Heat the mineral with 3 times its volume of soda on ch. Brittle metallic globules of Bi are obtained and a yellow coating of Bii'Os which is white further away.

176 Determination By Blowpipe Tests

Subl. much like that of Pb, but metal less malleable; distinguished by the following test.

(2) Iodide Ppt. on ch. and Plaster. Mix the powdered mineral with von KobelFs flux or moisten with HI and heat in the o.f. on ch. The subl. is yellow near the assay and bordered by brilliant red Bils. On a plaster plate the subl. is chocolate-brown but changes to a brilliant red on exposure to strong ammonia fumes.

BORON (B; trivalent; at.wt. 11)

(1) Flame Color. A somewhat yellowish-green (siskin-green) flame color. Compare Ba and MnC flame colors. Readily distinguished by other tests. Some B minerals require heating with 3 volumes of Turner's flux; the BF2 formed gives a momentary color to the flame.

(2) With Turmeric Paper. Moisten turmeric paper with a dilute HC1 sol. of the mineral and dry it on the outside of a test tube containing boiling water. The paper becomes reddish-bro\\n; on moistening with ammonia it becomes black. Insol. minerals must first be fused in fine powder with 3 volumes of soda on a loop of Pt wire and then dissolved in HC1.

BROMINE (Br; univalent; at.wt. 79.9)

(1) Precipitation as Bromide. Solutions of bromides in water or dilute HNOs yield a white ppt. of AgBr when AgNOs sol. is added.

(2) Pb Bromide Subl. in c.t. AgBr heated in c.t. with galena (PbS) yields a subl. of PbBr2, which is S-yellow while hot and white when cold.

CADMIUM (Cd; bivalent; at.wt. 112.4)

(1) Oxide Subl. on ch. Heated on ch. with 3 volumes of soda, metallic Cd is volatilized and sublimed as reddish-brown CdO, which is yellow distant from the assay and iridescent if only a little forms.

CALCIUM (Ca; bivalent; at.wt. 40.1)

(1) Flame Color. Some Ca minerals give yelh.-red color to the flame (green through green glass), often strengthened by moistening with HC1. Must not be confused with the much redder Sr and Li flames.

Reactions For The Elements 177

(2) Sulphate ppt. A few drops of dilute H2SO4 added to an HC1 sol. of a Ca mineral precipitates white CaSCU 2H2O, which goes into solution on addition of water and boiling. This sol. in water distinguishes it from Sr and Ba.

(3) Carbonate or Oxalate ppt. Ammonium carbonate or oxalate added to a solution made strongly alkaline with ammonia forms a white ppt. of the corresponding Ca compound. The oxalate is also formed in slightly acid solutions and this test can be applied in solutions of phosphates, silicates, and borates, which cannot be made alkaline with ammonia without precipitating Ca salts.

(4) Alkaline Reaction. Like other alkaline earths and most of the alkalis, some Ca minerals give an alkaline reaction on moist turmeric paper after ignition.

For Ca in silicates, see Silicon (2), page 185.

CARBON (C; tetravalent; at.wt. 12)

(1) Odor in c.t. The characteristic empyreumatic odor of distilling organic substances is given in c.t. by hydrocarbons and bituminous coal. Anthracite does not yield it, but is combustible in the o.f.

(2) from Carbonates. Heat fragments of the mineral in the c.t. held horizontally with a drop of in the open end of the tube; the latter is clouded wi£h a white ppt. of BaCOs.

(3) Effervescence with Acids/ Treat the powdered mineral with dilute HC1, HNOs, or HSCU, and warm if necessary. Guard against mistaking boiling for effervescence. Tip the test tube gently and pour accumulated CCb (gas) into another tube containing on shaking the latter a white ppt. of BaCOs forms. Concentrated acids do not yield the test unless the salts formed are soluble in the acids.

CHLORINE (Cl; univalent; at.wt. 35.5)

(1) Flame Color with CuO. Mix powdered mineral with CuO and moisten with HSCU, dry gently on ch. and ignite; or saturate a small s.ph. bead with CuO, add a fragment of the mineral and heat in the o.f. In either case the azure-blue flame of CuCl2 will appear. Br gives a similar reaction.

(2) Evolution of Cl. A powdered chloride heated in a small test tube with a little pyrolusite (MnO2) and 4 times its volume of KHSO4 gives off Cl gas, which is recognized by its pungent odor and its bleach-

178 Determination By Blowpipe Tests

ing effect on a piece of moist litmus paper placed inside the tube. AgCl and silicates containing Cl require fusion first with 3 volumes of soda.

(3) AgCl ppt. From a solution of a chloride in water or dilute HNOs a few drops of AgNOs sol. . white AgCl, curdy if abundant, bluish opalescent if little. Br and I give similar reactions. Light soon changes color of the ppt. to violet. Insoluble minerals must first be fused with 3 volumes of soda.

(4) Sublimate with Galena. To distinguish chloride, bromide, and iodide of Ag, heat in c.t. with powdered galena. A subl. of PbCl2 forms colorless globules which are white when cold; PbBr2 is S.-yel. hot and white when cold; Pbl2 is dark orange-red hot and lemon-yellow cold. The presence of Br obscures that of Cl, and I obscures both of the others.

CHROMIUM (Cr; trivalent and sexivalent; at.wt. 52)

(1) Borax Bead Reac. In o.f. yellow hot (red with much), yel.-grn. cold. In r.f. green hot and cold.

(2) S.ph. Bead Reac. In o.f. dirty green hot, clear green cold. In r.f. similar colors but weaker. V differs in giving yellow color to s.ph. bead in o.f.

(3) Soda Bead Reac. In o.f. dark yellow while hot, light yellow and opaque cold; in r.f. yelh.-green opaque when cold.

COBALT (Co; bivalent; at.wt. 59)

(1) In Borax and s.ph. Beads. Fine blue in both o.f. and r.f. When Cu or Ni interferes remove the bead from the Pt wire and fuse it on ch. with a granule of Sn and the Co color will appear.

COLUMBIUM (Niobium) (Cb; pentavalent; at.wt. 93.5)

(1) Reduction in Solution. Mix powdered mineral with 5 volumes of borax, moisten to a paste with water and fuse in a double loop of Pt wire (Fig. 796). Crush 2 or 3 such beads to powder and boil with HC1 to a clear solution. Add Sn and boil and the sol. becomes blue, which changes slowly to brown on continued boiling and disappears on dilution. With Zn instead of Sn the blue color changes quickly to brown. W gives similar tests, but other tests for that element will distinguish.

Reactions For The Elements 179

COPPER (Cu; bivalent and univalent; at.wt. 63.6)

(1) Flame Color. The oxide and oxidized sulphides give an emerald-green color. When moistened with HC1 the- flame is azureblue. The same result is obtained by adding a grain of common salt, NaCl, to a s.ph. bead saturated with the substance.

(2) Metallic Cu on ch. Oxides and sulphides that have been previously roasted yield globules of red malleable, Cu when fused in r.f . on ch. with 3 volumes of a flux of equal parts of soda and borax.

(3) Borax and s.ph. Bead Reactions. In o.f. green hot and blue cold; in r.f. pale with little Cu, red and opaque with much.

A ruby red transparent bead is obtained by adding a little tin or tin-bearing substance to a borax bead made pale blue with Cu in o.f. Dissolve thoroughly in o.f. and reduce slightly. If too much reduced the bead is colorless. A delicate test for either Cu or Sn.

(4) Color in Solution. Blue or green sol. in HNOs or HC1 made deep blue by adding ammonia in excess'. Ni gives a much fainter blue by similar treatment. '

(5) Cuprous Cu. Dissolve mineral in a little HC1 and add water. A white ppt. of cuprous chloride (CuCl) appears.

FLUORINE (F; univalent; at.wt. 19)

(1) HF in c.t. Mix the finely powdered mineral with an equal volume of powdered glass and 3 volumes of KHSCU and heat gently in c.t. The HF liberated attacks the glass and forms SiF4, which decomposes to HSiFe with separation of SiCb; this forms a volatile white subl. in the tube. Break off bottom of tube, wash subl. with water and dry; the remaining subl., is non-vol.

(2) Etching Glass. Mix powdered mineral with a few drops of cone. H2SO4 and spread over a glass that has been previously coated with paraffin and scratched with a pointed instrument. Let stand 5 minutes or longer. Wash off the acid, warm the glass, and wipe off paraffin to observe etching.

(3) With NaPOs in c.t. Mix the powdered mineral with 5 times the volume of powdered s.ph. beads and heat very hot in c.t. A subl. forms as in (1) and may be tested as there described.

GOLD (Au; univalent and trivalent; at.wt. 197.2)

(1) Metal with Soda on ch. The color, fusibility, malleability, and insolubility in any single acid serve to distinguish it from other metals when present in visible particles.

180 Determination By Blowpipe Tests

(2) Purple of Cassius. Carefully evaporate the solution in aqua regia to dryness, add a little water and dilute solution of stannous chloride (SnCk). The purple ppt. of colloidal Au and are soluble in ammonia to a reddish liquid.

HYDROGEN (H; univalent; at.wt. 1)

(1) Water in c.t. Minerals containing hydroxyl, acid hydrogen, or water of crystallization, when heated in c.t. give off water which condenses in the cold part of the tube. Hygroscopic water alone will give a slight test. Hydroxyl and acid H require high temperature. Some salts of weak bases yield acid water and from some ammonia compounds it is alkaline. Readily tested by a strip of litmus paper inserted in the tube.

IODINE (I; univalent; at.wt. 126.9)

(1) Iodide Subl. with Galena. Heat the powdered mineral with powdered galena in c.t.; a subl. of Pbl2 is formed which is dark orange-red while hot and lemon-yellow when cold.

(2) Ppt. with AgNO3. From dil. HNO3 solution AgN03 . white Agl, which differs from AgCl and AgBr in being nearly insoluble in ammonia.

(3) I with KHSO4. Violet I vapor is formed when iodides are heated in c.t. with KHS04.

IRIDIUM (Ir; trivalent and tetravalent; at.wt. 193.1) One of the rare Pt metals. See Platinum, page 184.

IRON (Fe; bivalent and trivalent; at.wt. 55.8)

(1) Magnetism. A few Fe minerals are magnetic and many become so on heating in r.f. (or roasting and then heating in r.f. in case of sulphides and arsenides). The test is more delicate if the powder is fused with a little soda, giving a magnetic slag. In all cases only the cold material is magnetic.

(2) Borax Bead Reac. With small amount of mineral the bead in o.f. is yellow hot and nearly colorless cold; in r.f. it becomes pale green hot and colorless cold. With much of the mineral it is bnh.- red hot and yellow cold ; in r.f. it becomes bottle-green hot and paler when cold. With sulphides and arsenides the bead test can be made only after roasting.

(3) Hydroxide ppt. When ammonia is added to a dil. HNOs sol. or to HC1 sol. which has been boiled with a few drops of HNOs,

f REACTIONS FOR THE ELEMENTS 181

a bnh.-red ppt. of is formed. In ferrous HC1 sol. ammonia gives a dirty green ppt. which slowly turns brown by oxidation.

(4) Ferrous and Ferric Fe. In cold dilute acid solutions potassium ferricyanide, gives a dark blue ppt. with ferrous Fe ; in ferric solutions it deepens the color but gives no ppt. Potassium ferrocyanide, gives a dark blue ppt. with ferric solutions; from ferrous sol. it gives a pale bluish-white ppt. which rapidly becomes blue. NH4CNS or KCNS gives a dark red color to ferric solutions.

Minerals insol. in acids must first be fused in c.t. with 3 volumes of borax glass (powdered borax beads) . Break off lower end of tube and boil in a little HC1 for a minute; dilute the sol., divide it into two parts, and test as above for ferrous and ferric Fe.

For Fe in silicates, see Silicon (2), page 185.

LEAD (Pb; bivalent and tetravalent; at.wt. 207.1)

(1) Metal and Subl. on ch. Mix 1 part powdered mineral, 1 part powdered charcoal, and 3 parts soda, moisten and fuse in r.f. on ch. Globules of soft, malleable, and sectile metal form, bright in r.f. and dull on cooling; also subl. of PbO, yellow near assay, bluish-white further away.

(2) Iodide Subl. on ch. Heat powdered mineral with 3 volumes of von Kobell's flux in o.f . on ch. A chrome-yel. subl. of Pbl2 forms near and greenish-yellow far from assay.

(3) . from Solution. From solution in dil. HNOs either H2S04 or HC1 forms a white ppt. (PbSO4 or PbCl2). From a boiling solution of the mineral in HC1 white PbCl2 crystallizes out on cooling.

LITHIUM (Li; univalent; at.wt. 6.9)

(1) Flame Color. Crimson flame when heated in Pt forceps or from powdered mineral on clean Pt wire (invisible through green glass). For silicates better results are obtained by mixing the mineral with equal parts of powdered gypsum. Flame color is much like that of Sr, but redder than that of Ca. Compare Sr and Ca.

MAGNESIUM (Mg; bivalent; at.wt. 24.3)

(1) Color with Cobalt Nitrate. Some light-colored Mg minerals become pale pink when strongly ignited after moistening with sol.

182 Determination By Blowpipe Tests

(2) Alkaline Reac. Some Mg minerals give alkaline reac. on moist turmeric paper after ignition, like the alkalis and alkaline earths, but weaker, and less decisive.

(3) Ppt. from Solution. Use HNO3 sol. or HC1 sol. that has been boiled with a drop of nitric acid, make strongly alkaline with ammonia, and remove Fe, Al, and Ca by successive precipitation with ammonia and ammonium oxalate, filtering each time a precipitate appears. To the clear filtrate add sodium phosphate. A crystalline ppt. of NH4MgPO4-6H2O appears after standing and cooling.

For Mg in silicates, see Silicon (2), page 185.

MANGANESE (Mn; bivalent, trivalent, tetravalent; at.wt. 54.9).

(1) Soda Bead Reac. Ifi o.f. green while hot, bluish-green cold; in r.f. white.

(2) Borax Bead Reac. In o.f. opaque while hot, reddish-violet when cold, black if too much is used. In r.f. colorless. Similar results in s.ph. but not so delicate.

(3) Evolution of Cl. Higher oxides of Mn decompose HC1 with evolution of Cl gas.

(4) Flame Color. HC1 solution gives yellowish green color to flame. Compare Ba and B flames. (See p. 161.)

MERCURY (Hg; univalent and bivalent; at.wt. 200)

(1) Metal in c.t. Mix the powdered mineral with 4 volumes of soda that has been dried by heating nearly to redness on clean metal or in a porcelain crucible; put mixture in c.t., cover with dry soda, and heat gradually. Hg appears as gray subl. or as globules on the walls of the tube. Alone in c.t. most Hg compounds volatilize without decomposing. Cinnabar gives a black subl. like the As mirror.

(2) Hg Ppt. on Cu. Clean Cu in a Hg sol. receives a coating of metallic Hg, giving the appearance of silver plating.

MOLYBDENUM (Mo; tetravalent and sexivalent; at.wt. 96)

(1) Subl. in o.t. Thin flakes of molybdenite at a high temperature in o.t. give a yellow subl. of MoOs, frequently also delicate crystals.

(2) Flame Color. At tip of blue flame gives a pale yelh.-green color.

(3) S.ph. Bead Reac. With a small amount of the oxide in o.f.

Reactions For The Elements 183

the bead is yelh.-green while hot, nearly colorless cold; in r.f. dirty green hot, fine green on cooling.

(4) Color in Sol. Place finely powdered mineral with a minute scrap of paper (about 1 mm. square) in a test tube with a few drops of water and an equal quantity of cone. H2S04; heat till copious acid fumes form, let cool, and add water, one drop at a time. A deep blue color appears and quickly disappears with much dilution.

NICKEL (Ni; bivalent; at.wt. 58.7)

(1) Borax Bead Reac. In o.f. violet while hot, redh.-brown cold; opaque by long heating in r.f. On ch. with Sn the bead becomes colorless. Co in small amt. obscures the bead test for Ni.

(2) Color of Sol. and Ppt. Sol. in HNOs is apple-green; becomes blue with ammonia. Compare the much deeper blue with Cu from this treatment.

(3) Dimethylglyoxime Test. To a solution of the mineral add ammonia in slight excess and a few drops of the reagent. A scarletcrystalline ppt. forms. If Fe is present add tartaric acid before ammonia. If very little Ni is present, boil, and red needles form on cooling. A very delicate test.

NITROGEN (N; trivalent and pentavalent; at.wt. 14)

(1) Deflagration on ch. Nitrates deflagrate (flash somewhat like gunpowder) upon ignition on ch.

(2) Fumes in c.t. Heat mineral powder in c.t. with KHSCU. NO? fumes given off are recognized by red color on looking into the end of the tube.

OSMIUM (Os; bivalent, tetravalent, etc.; at.wt. 190.9) One of the rare platinum metals. See Platinum, page 184.

OXYGEN (0; bivalent; at.wt. 16)

(1) O gas in c.t. Some higher oxides give off 0 when heated in c.t. A glowing stick inserted will burn brightly.

(2) Cl Gas with HC1. Some higher oxides decompose HC1 with the liberation of free Cl, which has a pungent odor and bleaches moist litmus paper inserted in the tube.

PALLADIUM (Pd; bivalent and tetravalent; at.wt. 106.7) One of the rare platinum metals. See Platinum, page 184.

184 Determination By Blowpipe Tests

PHOSPHORUS (P; pentavalent; at.wt. 31)

(1) Ppt. with Ammonium Molybdate. Dissolve the powdered mineral in HNOs, previously fusing in soda bead if insol. Add a few drops of the cold sol. to a test tube containing ammonium molybdate that has been made acid with HNOs and let stand a few minutes; a yellow ppt. forms. As gives similar ppt. in hot sol.

(2) Flame Color. Pale bluish-green; moistening with HSCU is required with some minerals.

PLATINUM (Pt; bivalent and tetravalent, at.wt. 195.2)

(1) Platinum is recognized by its grayish-white color, infusibility, insolubility in any single acid, and reddish-yellow solution in aqua regia. It usually contains iron and traces of the other metals of the platinum group. These require special methods for identification. When pure or nearly so the following may be recognized:

(2) Osmium gives the very penetrating and disagreeable odor of OsO4 when the fine powder is heated in c.t. with NaNOs or KNOs.

(3) Indium and Iridosmium are hard (H 6 — 7), insoluble even in aqua regia. Fusion with NaNOs in c.t. oxidizes some Ir; break off the lower end of the tube and boil the mass in aqua regia. The solution becomes deep red to reddish-black.

(4) Palladium has a bluish tarnish, which is removed and a Pt-like color restored in r.f. The tarnish is renewed by moderate heat in o.f .

POTASSIUM (K; univalent; at.wt.39.1)

(1) Flame Color. Pale violet, obscured by Na; violet or purplish-red through blue glass, which eliminates the yellow of Na. For silicates mix with an equal volume of powdered gypsum and heat on a Pt wire the end of which has been moistened to make the powder adhere.

(2) Alkaline Reaction. Some K minerals, like those containing some other alkalis and the alkaline earths, give an alkaline reac. on moist turmeric paper after intense ignition.

For K in silicates, see Silicon (2), page 185.

SELENIUM (Se; bivalent and sexivalent; at.wt. 79.2)

(1) Odor and Subl. on ch. Radish-like odor. If abundant, brownish fumes form and a silvery Se02 coating, which may have a border of red from admixture of Se.

Reactions For The Elements 185

(2) Flame Color. The subl. obtained in (1) is volatile in r.f. and imparts a fine azure-blue color to the flame.

(3) Subl. in o.t. White crystalline SeO2 subl. reddened by admixture of Se; volatile and gives a beautiful blue color to flame if the end of the tube is held so that the fumes enter the reducing part of the Bunsen flame.

(4) Subl. in c.t. Fused black globules of Se, the smallest deep red to brown by transmitted light. Some white may form above the Se.

SILICON (Si; tetravalent; at.wt. 28.3)

(1) Gelatinization. Many silicates are completely soluble in acids and give on continued boiling and evaporation a jelly of HSiOs. HNOs is best, but HC1 will serve in most cases. All silicates, when first fused with 5 parts of soda and dissolved in dilute HC1 and evaporated, yield gelatinous silica. It is convenient to use the double loop (Fig. 796) and prepare 2 or 3 large beads, in order to provide a sufficient quantity for distinct reactions. This is especially important in the tests under the next section.

(2) Insol. Residue in Acids. Insol. silica in powdery form remains after solution of the bases of some minerals. In suspension it makes the solution translucent and not so white and milky as the powder of an insol. mineral. Verify solution by evaporating a drop of the clear liquid on Pt foil or a watch glass (or a flake of mica if HC1 or HNOs is used) and note considerable residue if solution has occurred.

Evaporate the solution obtained in (1) or (2) to dryness, moisten with cone. HC1, and heat to boiling, then add 2 parts water and boil again. The bases go into sol. but the silica remains and is removed by filtering. For insol. silicates first fuse with soda, as directed in the preceding section.

Detection of Bases in Silicates, (a) To the filtrate from the preceding operations if not a nitric acid solution, add a little HNO3, heat to boiling and add ammonia in slight excess. Al and Fe are precipitated as hydroxides, and Fe If the ppt. is light colored there is little or no Fe; if it is reddish brown there is considerable Fe and further test must be made for Al as follows: (6) Filter; place the ppt. in a test tube with a little water and a small fragment of stick potash (KOH) and boil. goes into solution and is separated from insoluble by filtering. Make the filtrate acid with HC1, boil, and add ammonia in excess to precipitate again.

(c) Heat filtrate from (a) to boiling and add a little ammonium oxalate to precipitate Ca. Let stand ten minutes and filter. If filtrate is turbid, pass it repeatedly through the same filter till it comes through clear.

(d) Add to the filtrate from (c) a little more ammonium oxalate to make sure

186 Determination By Blowpipe Tests

that all Ca has been removed. If no ppt. forms add sodium phosphate and strong ammonia to precipitate Mg. It may have to stand for some time after cooling before the precipitate forms.

(e) If alkalis are to be tested for, filter off the Mg ppt. of (d), evaporate the filtrate to dryness and heat to redness to drive off ammonia salts. Test the residue for K and Na flame colors with a Pt wire.

(3) In s.ph. Bead. Silica dissolves very slowly in s.ph., hence a " skeleton " of translucent silica remains after treating a powdered silicate in s.ph. bead.

SILVER (Ag; univalent; at.wt. 107.9)

(1) Metal on ch. Fuse powdered mineral with 3 volumes of soda on ch.; a malleable metal globule is obtained which is bright both in the flame and after cooling. Test according to (2) below. Compounds with S, As, and Sb on roasting in o.f. on ch. yield Ag globule which is brittle with Sb.

(2) Subl. on ch. When Pb and Sb are present or have been added, the subl. of PbO and Sb20s on ch. is colored reddish to deep lilac by Ag.

(3) AgCl Ppt. Dissolve the mineral in cone. HNOs and dilute the sol. ; add a few drops of HC1 or a little common salt and a white ppt. of AgCl forms. Darkens on exposure to light and is sol. in ammonia. Collect ppt. on filter paper and test according to (1) above.

SODIUM (Na; univalent; at.wt. 23)

(1) Flame Color. Deep pure yellow, invisible through dark blue glass. For non-vol. silicates mix powdered mineral with equal volume of powdered gypsum and heat on the point of a Pt wire which has been previously moistened so that powder will adhere.

Everything that is touched by the hands gives a distinct Na flame, so delicate is the test; hence it is of diagnostic value only when the flame color is deep and persistent.

(2) Alkaline Reac. Some Na minerals, like those containing most other alkalis and the alkaline earths, give alkaline reac. on moist turmeric paper after ignition.

For Na in silicates, see Silicon (2), page 185.

STRONTIUM (Sr; bivalent; at.wt. 87.6)

(1) Flame Color. Crimson, from fragment in forceps or from powder on Pt wire moistened with HC1 (faint yellow through green

Reactions For The Elements 187

glass). Much like the Li flame; redder than the Ca flame and more persistent.

(2) Alkaline Reac. Like many minerals containing alkalis and other alkaline earths, some Sr minerals give alkaline reac. on moist turmeric paper after ignition. No Li minerals give this reaction.

(3) Sulphate ppt. A sol. of a Sr mineral gives a white ppt. of SrSCU on addition of a few drops of dil. H2SO4 (dif. from Li) if sol. is not very dilute or too much acid. Ppt. does not dissolve on addition of water and boiling, as does CaS04. This test is useful for silicates and phosphates, which do not yield tests (1) and (2).

SULPHUR (S; bivalent and sexivalent; at.wt. 32.1)

Sulphides :

(1) Fumes in o.t. and on ch. Finely powdered sulphides in o.t. give sharp pungent 862 fumes, which give acid reac. on moist litmus paper in upper end of tube. With Fe and Cu some white fumes of SOs appear and H2S04 condenses in the tube. Similar results on ch. in o.f., but less delicate. Some sulphides give blue flame from burning S on ch.

(2) Subl. in c.t. Some sulphides yield in c.t. a subl. of S, which is a reddish liquid while hot and a yellow solid when cold.

(3) Reac. with Soda. Fuse powdered mineral b.b. on Pt foil, ch., or a flake of mica, with 3 volumes of soda, place the mass on clean Ag and moisten with water; a black stain of Ag2S forms. The' fused mass moistened with HC1 yields EkS, as in (5) below. This test is not reliable in the presence of Se and Te. Also the gas or ch. may give a slight reac. for S.

(4) Sol. in HNOs. In hot cone. HNOs sulphides are oxidized with the formation of HSCU and red N(>2 fumes. Dilute part of the sol. and add BaClo; a white ppt. of BaSCU forms. Free S may also float on the solution, either yellow or blackened with particles of the mineral.

(5) H2S with HC1. Some sulphides dissolve in HC1 with the evolution of EkS gas, which is recognized by its offensive odor.

Sulphates:

(1) BaSO4 ppt. BaCl2 added to a dil. HG1 sol. of a sulphate gives a white ppt. of BaSCU, which does not dissolve on addition of water and boiling, as does CaSO4.

(2) Reac. with Soda. Fuse the powdered mineral with equal volume of powdered ch. and 2 volumes of soda on ch., Pt foil, or a

188 Determination By Blowpipe Tests

flake of mica till effervescence ceases; then test on Ag or with HC1 as in (3) for sulphides.

. TELLURIUM (Te; bivalent; at.wt. 127.5)

(1) Color of Sol. Finely powdered mineral heated gently in cone. H2S04 gives reddish violet sol. After cooling add H2O; color disappears and grayish black ppt. of Te forms. Similar color from Mn minerals with cone. does not disappear on dilution.

(2) Subl. on ch. Heated in o.f. on ch. a white subl. of TeO2 forms near assay, resembling Sb20s. Subl. is vol. in r.f. and gives a pale greenish color to the flame. Similar results in o.t.

(3) Subl. in c.t. Metallic globules of Te and white subl.

TIN (Sn; tetravalent; at.wt. 119)

(1) Reduction by H. With dil. HC1 and fragments of Zn cassiterite develops a dull gray coating of metallic Sn, which becomes bright and gives the characteristic odor of Sn on flesh when rubbed between the fingers.

(2) Metal and Subl. on ch. The powdered mineral fused on ch. in r.f. with equal volume of powdered ch. and 2 volumes of soda gives globules of white malleable Sn, which are bright in r.f. and become dull in the air. Long-continued ignition gives a white subl. of SnC on ch. In somewhat cone, warm HNOs the metal does not dissolve but forms white HSnOa, as do also the sulphides. Distinguished from Pb and Bi by accompanying subl. on ch. and from Ag by subl. and dull surface of globule in air.

For a delicate borax bead test, see Copper (3), page 179.

TITANIUM (Ti; trivalent and tetravalent; at.wfc. 48.1)

(1) Color of Sol. After fusion with borax or soda and solution in HC1, the sol. assumes a delicate violet color on boiling with Sn.

(2) S.ph. Bead Reac. In o.f. yellow while hot, colorless cold; in r.f. yellow hot, delicate violet cold. Best reduced with a granule of Sn on ch. When other coloring elements are present use test (1), above.

(3) Test with H2O2. Fuse the mineral with soda, boil in a small amount of cone. H2SO4 and an equal volume of water till clear. Dilute and add EfeC; the sol. becomes yellow to amber, according to the quantity of Ti. A delicate test.

Reactions For The Elements 189

TUNGSTEN (W; sexivalent; at.wt. 184)

(1) S.ph. Bead Reac. In o.f. colorless; in r.f. green hot, fine blue cold.

(2) Residue in HC1. When decomposed by HC1 a yellow residue of WOs is obtained. Add Sn and continue boiling; a blue color is produced, which finally changes to brown. If insol. in HC1, fuse powder on Pt wire with 6 volumes of soda, pulverize and dissolve in water, filter, acidify with HC1, and boil with Sn. The sol. becomes blue. A delicate test.

(3) Reduction on Al. To a drop of water on Al add the finely powdered mineral and a small drop of HC1. A blue color develops on standing.

URANIUM (U; tetravalent and sexivalent; at.wt. 238.5)

(1) S.ph. Bead Reac. In o.f. yellow while hot, yelh.-green cold; in r.f. a fine green.

VANADIUM (V; pentavalent; at.wt. 51)

(1) S.ph. Bead Reac. In o.f. yellow to deep amber, fading a little on cooling; in r.f. dirty greenish while hot, fine green cold.

(2) Color of Sol. To an acid sol. add a few drops of H2O2. The sol. becomes reddish-brown from pervanadic acid, HVO4. A very delicate test.

ZINC (Zn; bivalent; at.wt. 65.4)

(1) Subl. on Ch. Make a paste of the finely powdered mineral, half its volume of soda, and a little water. The mineral must first be thoroughly roasted if S, As, or Sb is present. Heat some of the paste in a small loop of Pt wire, which is held about half an inch from the surface of charcoal (Fig. 81), so that volatilized products are carried by the flame directly against the coal. Using a small bead and an intensely hot reducing flame, Zn is reduced to the metallic state, volatilized, and then, uniting with O at the

A -j e j-u a j FIG. 81.— Method for Zinc

outside of the flame, is deposited as a Sublimate

circular coating, which is canary-yellow

while hot and white when cold. If a spot has previously been

190 Determination By Blowpipe Tests

moistened with sol., the sublimate is grass-green at that point.

(2) Flame Color. A large fragment heated near 'the tip of the blue flame colors it in streaks a vivid pale bluish-green.

(3) Change of Color. Many Zn minerals are straw-yellow or canary-yellow while hot and white when cold.

(4) Color with Infusible, light colored Zn minerals, when powdered, moistened with and intensely heated, become green, except silicates, which assume a blue color, generally with some green also.

ZIRCONIUM (Zr; tetravalent; at.wt. 90.6)

(1) Turmeric Paper Test. Fuse the powdered mineral with soda in a loop of Pt wire and dissolve the bead in a small amount of HC1. Turmeric paper placed in the solution assumes an orange color, which is detected by comparing with a piece of turmeric paper in another tube containing only acid.

Tables For The Determination Of

Minerals By Means Of The Blowpipe

And Chemical Tests

Preliminary Instructions And Precautions

THE tables are constructed on the plan of eliminating one group of minerals after another until the proper species is found; hence the order as given must be followed strictly, both in the general table and in the sections to which it refers.

Each test should be recorded as soon as made, whether results are negative or positive. This may be done in systematic order in a notebook, as suggested on the next page.

If the crystal system can be determined, either from crystals or from cleavage, comparison with the crystal tables, pages 266 to 274, will often prove the most convenient means of identification.

Whenever possible, tests should be made only upon fresh/ homogeneous material, preferably crystalline. If an impurity can be detected its effect must be carefully allowed for and not attributed to the mineral. For example, surface stains of iron oxide and thin films or small amounts of intermingled calcite or other carbonate are often present and may mislead by discoloring the acid or yielding a temporary effervescence. In case of doubt, decant after boiling and note whether or not the same results are obtained with fresh acid.

The powdered mineral required for many of the tests should be prepared by crushing and grinding (not pounding) small grains of pure material under a hammer on any clean surface of iron or steel. (Fig. 69.) If the mineral is rare and but little can be had for determination, fragments may be wrapped in two or three folds of paper and pounded with a hammer.

All tests must be made with care, and only clear, decided reactions taken into account. Weak uncertain results may be due to the

192 Tables For The Determination Of Blowpipe Tests

presence of a small amount of some impurity, but often they are the results of careless or hasty manipulation. In every test follow closely the detailed instructions, pages 156 to 174.

The importance of scrupulous care in making acid tests and critical observation of the results cannot be over-emphasized. The student should be thoroughly familiar with the instructions on pages 170 to 173.

Dilute HC1 (that is, cone. HC1 with an equal volume of water) is always understood in acid tests, unless otherwise specified. In many tests the concentrated acid will not yield as good results.

Do not fill a test tube with acid or other reagent to a depth much greater than its diameter, if it is to be boiled.

When igniting a mineral alone on charcoal, use small particles — about the size of a pin head — and use only as many as can be thoroughly heated in the blowpipe flame.

Do not use the Pt-tipped forceps with a mineral of metallic luster nor with one that yields a rnetal on charcoal.

Many of the " Instructions and Precautions" given in connection with the physical tables, page 12, also apply equally here.

Laboratory Records

For each mineral determined record should be made of tests and diagnostic characters, in the order in which they are met in the tables. Small loose-leaf note-books, with paper about by 5J inches, furnish ample space and have been found most convenient for this purpose.

Such records are particularly useful in case of error, and the separation into two parts, belonging to the general and the special tables, respectively, is also an advantage. The condensed skeleton form saves much of the student's and instructor's time without sacrificing clearness.

Emphasis should be placed on the necessity of recording each test immediately upon its completion.

The following records of the determination of pyrite and orthoclase will serve as illustrations.

Laboratory Records

No. 37

Luster metallic Fus. 3; S02 fumes No As nor Sb

(Sec. 3, p. 200)

No Ag, Pb, nor Cu Becomes mag. in o. f. Color brass-yellow Soluble in cold cone. HNOa No S residue

P YRITE, FeS2 Use: Mfr. H2S04

J. R. Brown May 20, 1981

No. 38

Luster vitreous', d. pearly Fus. 4~5', no flame color No metal w. ch. and soda Not mag. nor alk. after ign. Insoluble in HC1 Cl. 2 direc. about 90°

(Sec. 23, p. 238)

G.2.57', Feldspar Group K flame w. gypsum Cl. faces not striated

ORTHOCLASE KAlSi308 Use: Pottery mfr.

J. R. Brown

May 20, 1921

General Table

Caution. — In all chemical tests follow carefully the methods outlined on pages 174 to 190.

(For glossary and abbreviations, see pages 275-286.)

I. Metallic Or Submetallic Luster

A. Fusible, at least on thin edges (fus. 1-5), or volatile: SEC. PAGE

1. As minerals. White subl. on ch. far from assay; commonly

also garlic odor 1 196

2. Sb minerals. — Dense white subl. on ch. near assay 2 198

3. Sulphides, no As nor Sb. — Use soda test (p. 187) if SO2 fumes

not observed on ch 3 200

4. Not previously included 4 202

B. Infusible or nearly so (fus. above 5) :

1. Fe minerals. — Strongly magnetic or become so after heating

in r.f . and cooling 5 206

2. Mn minerals. — Minute quantity gives Mn reaction in soda or

borax bead; sol. in HC1 with evolution of Cl gas 6 208

3. Not previously included 7 210

Ii. Luster Not Metallic

A. Easily volatile or combustible 8 212

B. Fusible, at least on thin edges (fus. 1-5), or slowly or partially

volatile:

Part I. Metal globules when fused on ch. with equal volume of powdered ch. and 3 volumes of soda:

1. Pb minerals. — Yellow subl. and Pb globules on ch.; with

von Kobell's flux a chrome-yellow coat, darker while hot. 9 214

2. Cu minerals. — Cu globules; Cu reactions with acids 10 214

3. Ag and Bi minerals. — Ag-white metallic globules 11 216

Part II. Magnetic after heating in r.f. and cooling; Fe, Ni, and

Co minerals: 1. Fine powder sol. in HC1 without residue or formation of gel.

silica upon evaporation 12 218

General Table 195

2. Fine powder sol. in HC1 with gel. silica, or decomposed with SEC. PAQE

separation of silica (latter more translucent and settles

more slowly than mineral powder) 13 220

3. Fine powder insol. in HC1 or nearly so 14 220

Part III. Not included in the foregoing Parts I and II.

1. Alkaline reaction on moist turmeric paper after intense

ignition:

a. Fine powder easily and completely soluble in water. . . 15 224

b. Fine powder insol. in water or only slowly or partially

soluble 16 226

2. Fine powder sol. in HC1 without residue or formation- of gel.

silica upon evaporation 17 228

3. Fine powder sol. in HC1 with gel. silica:

a. Give water in closed tube 18 230

b. Little or no water given in closed tube 19 230

4. Fine powder decomposed by HC1 with separation of flaky

or granular silica (more translucent and settles more slowly than mineral powder) or yellow WO3 powder:

a. Give water in closed tube 20 232

b. Little or no water given in closed tube 21 234

5. Fine powder insoluble in HC1 or nearly so:

a. Micaceous, scaly, or foliated 22 236

6. Distinct cleavage 2 directions — feldspars, amphiboles,

pyroxenes 23 238

c. Mn reaction in soda bead 24 240

d. Not previously included 25 242

C. Infusible or nearly so (fus. above 5) :

1. Alkaline reaction on moist turmeric paper after intense ignition. 26 246

2. Fine powder sol. in HC1 without residue or formation of gel.

silica upon evaporation 27 248

3. Fine powder sol. in HC1 with gel. silica 28 252

4. Fine powder decomposed by HC1 with separation of flaky or

granular silica (more translucent and settles more slowly than

mineral powder) or yellow WO3 powder 29 254

5. Fine powder insol. in HC1 or nearly so:

a. Can be scratched with knife blade (H below 6) 30 254

b. Cannot be scratched with knife (H 6 or harder) 31 258

SECTION 1. Metallic luster:

Name.

Composition.

Vol. on ch. without fusion

As subl. in c.t.

ARSENIC (See p. 28)

As (Sb Iso. w. As)

Mag. globule on ch.

(Compare Co and Ni minerals below.)

As and S reac. in o.t. As in c.t.; red subl. precedes

Arsenopyrite

(Misplckel) (See p. 16)

(Co Iso. w. Fe)

As, but little or no S

Lollingite (Leucopyrite) (See p. 15)

FeAs2 to Fe3As4 (Some S, somet. Co.)

Cu flame on ch. after roasting and moistening with HC1. SO2 fumes in o.t. Pearceite has triangular markings on basal planes.

Disting. by phys. properties (Cp. tetrahedrite)

ENARGITE (See p. 20)

Cu3AsS4 (Some Sb)

Tennantite (See p. 21)

Cu3AsS3 (Ag, Zn, Fe, Sb, Iso.)

Ag w. soda on ch. (Cp. polybasite)

PEAECEITE (See p. 20)

Cu flame on ch. as above; no SO-2 fumes in o.t.

Disting. by phys. properties. All tar. to bnh. color. Whitneyite is rdh. on rubbed surface and malleable

Domeykite

Cu3As

Algodonite

Cu6As

Whitneyite

Cu9As

Rose col. sol. in cone. HNOa; Co in borax bd. after roasting (Compare Ni minerals, below)

As subl. in c.t.

SMALTITE (See p. 16)

CoAs2 (Fe, Nl Iso. w. Co)

As and S reac. in o.t., little or none in c.t.

Cobaltite

(See p. 15)

CoAsS (Fe Iso. w. Co)

Glaucodot

Apple-grn. sol. in HNOs and dimethylglyoxime test for Ni, abundant ppt.; Ni in borax bd. after roasting. (May be masked by Co)

As subl. in c.t.

CHLOANTHITE (See p. 16)

NiAs2 (Fe, Co Iso. w. Nl)

As in c.t. on intense ign.

NlCCOLITE (Copper Nickel) (See p. 25)

NiAs (Fe, Co Iso. w. Nl)

As and S reac. in o.t. S res. in cone HNOs

GERSDORFFITE (See p. 15)

NiAsS (Fe, Co Iso. w. Nl)

Ag in HNO3 sol., S set free

A bund, deep red subl. in c.t., rdh.-yel. cold; slight S subl. above it

PROUSTITE (Ruby Silver) (See p. 137)

Ag3AsS3 (Somet. Sb)

fus. 1-5 or vol.; As subl. on ch.

Color.

Streak.

Hardness.

Specific Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fracture.

Sn-wh.; tar. dk. gry.

Gry.

Vol.

Hex. rhom.; us. crusts

C. 1, basal, per. F. uneven

Ag-wh. to Fe-gry.

Blk.

5f-6

Orth.; gran.; comp.

C. 2, prism., 68°, poor F. uneven

Ag-wh. to steel-gry.

Blk.

Orth.; gran.; comp.

C. 1, basal, poor F. uneven

Gryh-blk.

Gryh-blk.

Orth.; gran.; comp.

C. 2, prism., per., 82° F. uneven

Dk. Pb-gry. to Fe-blk.

Blk. to dk. cherry-red

a

Iso. tetrh.; xls. Figs. 13, 14, 17; comp.

F. uneven

Blk.

Blk.

Mon; tabular, comp.

F. conch.

Sn-wh. to steel-gry.

Gry.

3 -3£

Massive

F. uneven

Steel-gry.

Gry.

Massive

F. uneven

Pale rdh. to gryh-wh.

Ag-wh.

3£

Massive

Malleable F. hackly

Sn-wh.

Blk.

Iso. pyrito.; gran. ; comp.

C. 4, oct. 70§°, poor F. uneven

Ag-wh. to gry. w. rdh. tone

Blk.

Iso. pyrito.; Figs. 5, 18, 20

C. 3, cubic, poor F. uneven

Gryh-wh.

Blk.

Orth.

C. basal F. uneven

Sn-wh.

Gryh-blk.

Iso. pyrito.; gran.; comp.

C. 4, oct., 70£° F. uneven

Pale Cu-red

-blk.

Hex.; comp.; dissem.

F. uneven

Sn-wh.

Blk.

Iso. pyrito.; gran.

C. 3, cubic, poor F. uneven

Scarlet to rubyred

Scarlet

Hex. rhom., hemimor; compact.

C. 3, rhom. poor F. conch.

SECTION 3. Metallic luster;

Name.

Composition.

Easily and completely vol. on ch.; no Pb reac.. Stibnite, slender xls. slightly flexible

Wh. slowly vol. subl. in o.t.

Antimony (See p. 28)

Sb (Somet. Ag, Fe, As)

SO2 and wh. non-vol. subl. in o.t.

Stibnite

(Antimony Glance) (See p. 18)

Sb2S3

Cu reac. in HNO3 sol. No Pb or Ag globule w. soda on ch.

May contain Pb, Ag, Zn, Fe, and As

TETRAHEDRITE (Gray Copper) (See p. 21)

Cu3SbS3 (Fe, Zn, Pb. Ag Iso. w. Cu; As Iso. w. Sb)

Ag reac. in HNOa sol. w. HC1; no Pb. Ag globule after roasting and fus. w. soda on ch. Subl. red to lilac when only Ag, Sb, and S are present

Cu reac. in HNOs sol.; mineral gray

FREIBERGITE (Ag Tetrahedrlte) (See p. 21)

(Fe, Zn Iso. w. Cu2; some As)

Deep red to blk.; st. Indian-red

PYRARGYRITE Ruby Silver, Dark Red Silver Ore) (See p. 129)

AgsSbSs (Somet. As)

Blk., stout 6-sided (orth.) prisms

STEPHANITE (Brittle Silver Ore) (See p. 18)

Ag5SbS4

Blk., 6-sided (mon.) plates ; triangul ar markings on basal plane

POLYBASITE (Cp. peareclte, p. 196) (See p. 19)

(As Iso. w. Sb)

Sb and Ag reac. No S. Sectile

Dyscrasite (See p. 28)

Pb reac. after roasting and fus. on ch. w. von Kobell's flux

Cu reac. with HNO3 sol.; steel-gry.

BOURNONITE (Cogwheel Ore) (See p. 20)

No Ag or Cu

JAMESONITE (Feather Ore) (See p. 14)

Pb2Sb2S5 (Often Fe)

Zinkenite

PbSb->S4

fus. 1-5 or vol.; Sb subl. on ch.

Color.

Streak.

Hardness.

Specific Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fracture.

Sn-wh.

Sn-wh.

3 -3£

Hex. rhom.; us. mass.

C. 1, basal, per. F. uneven

Pb-gry.

Pb-gry.

Orth.; long

prism.; xls.

C. 1, pinac. per. F. uneven

Gry. to

Fe-blk.

Gry. to Fe-blk.

Iso. tetrh., Figs. 13, 14, 17; comp.

F. uneven

Steel-gry.

Blk., often rdh.

Iso. tetrh.

F. uneven

Deep red to blk.

Purplish red

Hex. rhom.; hemimor. ; dissem. ; comp.

C. 3, rhom., poor, 72° F. conch., uneven

Fe-blk.

Fe-blk.

2 -2£

Orth.; comp., dissem.

F. uneven

Fe-blk.

Blk.

Mon., tabular; comp.; dissem.

C. 1, basal, poor F. uneven

Ag-wh.

Ag-wh.

a

Orth.; comp.; gran.

C. 3, basal and prism, 56°, 68° 124°

Steel-gry.

Fe-gry.

Orth.; gran.; cogwheel twins

F. uneven

-gry.

Gryh-blk.

Orth.; acic., feathery

C. 1, basal, per. F. uneven

Steel-gry.

Steel-gry.

Orth.

F. uneven

SECTION 3. Metallic luster;

Name.

Composition.

Ag globule in o.f. on ch.

Contains only Ag and S. Sectile

ARGENTITE (Silver Glance) (See p. 18)

Ag2S

Pb globule and yel. subl. on ch.

Galena

( Galenlte) (See p. 19)

PbS

(Often some Ag)

Cu flame on ch. after roasting and moistening w. HC1

Mag. in o.f. (Stannite only after long ign.) (Millerite, below, may have Cu impurities)

Brass-yel.

Chalcopyrite

(Copper Pyrites) (See p. 24)

-bronze, purple tar.

BORNITE (Peacock, Ore) (See p. 24)

Cu5FeS4

Steel-gray.; wh. subl. in o.f.

Stannite (Tin Pyrites) (See p. 15)

Cu2FeSnS4 (Zn Iso. w. Fe)

Not mag. in o.f. (unless impure from admixture of bornite, etc.)

Cu in r.f. after roast ing. Covellite much Sinc.t.,Chalcocite none

Chalcocite

(Copper Glance) (See p. 19)

Cu2S (Somet, Fe)

COVELLITE (Indigo Copper) (See p. 17)

CuS

Ag reac. in HNO3 sol.

STROMEYEBITE (See p. 20)

Mag. in o.f. ; no Cu. Contains Fe, Co, or Ni,

(Continued on next page)

Pale brass-yel. Completely sol. in cold cone. HNOs

Pyrite

(Iron Pyrites; Fool's Gold) (See p. 26)

FeS2 (Somet. Cu. Au. Nl, Co)

Pale brass-yel to wh. S separates from cold cone. HNO3 sol.

Marcasite

(White Iron Pyrites) (See p. 26)

FeS2 (Somet. As)

FeS (Nl Iso. w. Fe) S in sol. up to 3|%

ZnS (Fe. Mn, Cd, Iso. w. Zn)

ZnS (Some Fe)

Decomposed by HC1 with evolution of H2S.

-bronze ; us. mag.; st. blk.

Pyrrhotite

(Magnetic Pyrites; Mundlc)

(See p. 25)

Zn reac. w. soda; submetallic luster.

Sphalerite

(Zinc Blende; Black Jack) (See p. 88)

Wurtzite (See p. 130)

fus. 1-5 or vol; no As nor Sb; SO2 in o.t.

Color.

Hardness.

Specific Gravity.

Fusi.- bility.

Crystallization and Structure.

Cleavage and Fracture.

-gry.

-gry.

2 -2£

u

Iso., us. comp.

F. hackly, sectile

Pb-gry.

Pb-gry.

Iso.; us. xls. or gran. Fig. 5

C. 3, cubic, per. 90<

Brass-yel.

-blk.

Tet. sphenoidal ; us. comp.

F. uneven

-red bronze Purplish tar.

Pale gryh-blk.

Iso. ; us. comp.

F. uneven

Steel-gry. to Fe-blk.

.

Tetrag.,us. comp.

F. uneven

Dk. Pb-gry . or blue tar.

Dk. Pb-gry.

Orth. ; us. mass.

F. conch.

Indigo-blue

Pb-gry. to blk.

H-2

Hex.; us. comp. or crusts

C. 1, basal, per., thin flakes flexible

Dk. steel-gry.

Dk. steelgry.

ift

Orth.; us. comp.

F. uneven slightly sectile

Pale brass-yel.

-blk. to -blk.

6 -6J

Iso. pyrito. ; Figs. 1, 5, 18, 20; dissem.

F. uneven.

Pale yel. to almost wh.

Gryh. or -blk.

6 -6£

Orth.; tabular; pyram.; cockscomb xls.

C. 2, prism., 75°, poor F. uneven

Yelh. to bnh. bronze

Blk.

3Mj

Hex.; us. comp., gran.

C. 1, basal, poor F. uneven

Dk. bra. to blk.

Lt. to dk. brn.

Iso. tetr.; us. gran., comp.

C. 6, dodec., per., 60°, 90°, 120° F. conch.

Bnh-bik.

Bra

Hex. hemimor., fibr.

F. uneven, splintery

SECTION 3.— Concluded. Metallic luster;

Name.

Composition.

Mag. in o.f.; no Cu. — Concluded

HNOs sol. grn. Ni in borax bd. after roasting. Millerite capillary xls. or velvety crusts; Pentlandite gives Fe ppt. w. am. from HNO3 sol.

MILLERITE (Hair Pyrites) (See p. 24)

NiS (Slender xls. elastic)

PENTLANDITE (See p. 25)

HNOs sol. rose col. Co in borax bd. after roasting

(See p. 15)

(Fe. Cu Iso. w. Co)

Hg subl. in c.t. with dry soda

SO2 and Hg in o.t., blk. subl. in c.t.

Cinnabar

(See p. 137)

HgS

(Us. w. Fe2 Os. clay, bitumen)

Bi reac. w. von Kobell's flux

Te reac. w. H2SO4

Tetradymite

Contains only Bi and S Fuses with spiriting

Bismuthinite (Bismuth Glance) (See p. 14)

Bi2S3

Mn in borax bd. after roasting

H,S in HC1

ALABANDITE (See p. 148)

MnS

Rdh-violet sol. when gently heated in cone. H2SO4 (See p. 188)

TELLURIDES See page 206

SECTION 4. Metallic luster;

Native metal, malleable

Cu reac. w. HNO3 sol.

Copper

(See p. 138)

Cu (Often Ag, BI, Hg)

Ag reac. w. HNOs sol. (Cp. amalgam below)

Silver

(See p. 27)

Ag

(Somet. w. Au, Cu, Hg)

Insol. in NHO3

GOLD (See p. 139)

Au

(Us. w. some Ag)

Insol. in NHO3; much Ag

Electrum (See p. 139)

(Au.Ag)

Native metal, brittle or liquid

Bright red subl. on ch. w. von Kobell's flux

BISMUTH (See p. 27)

Bi

(Often S and Te)

Hg subl. in c.t.; amalgam leaves Ag res.

Mercury (Quicksilver) (See p. 26)

Hg

(Somet. Ag)

Amalgam (See p. 28)

(Ag.Hg)

fus. 1-5 or vol.; no As nor Sb; SO2 in o.t.

Color.

Streak.

Hardness.

Specific. Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fracture.

Brass-yel.

-blk.

3 -3£

1J-S

Hex. rhom. ; us. capil, fibr., crusts

C. rhom. F. uneven, splintery

Lt. bronze yel.

Blk.

3M

U-2

Iso., gran., comp.

C. 4, oct., 70£°, 109*° F. uneven

Palo steel-gry. ; tar. Cu-red

Gryh-blk.

Iso., xls., Fig. 1

C. cubic, 90° poor F. uneven

Conchineal-red to bnh.

Scarlet

Vol.

Hex. rhom.; gran., earthy

C. 3, prism, per., 60° F. uneven

Pale-steel gry.

Gry.

U-2

Hex. rhom.; us. bladed.

C. basal per., thin flakes flexible

Lt. Pb-gry.

Lt. Pb-gry.

Orth.; gran., fol., fibr.

C. 1, pinac., per., slightly sectile

Fe-blk. Brn. tar.

Olive-grn.

Iso. tetr.; comp.

C. 3, cubic, per. 90° F. uneven

fus. 1-5 or vol. ; no As, Sb, nor S

Cu-red, Tar-blk.

Cu-red, shiny

2£-3

Iso. ; scales, plates

F. hackly Duct, and mall.

Ag-wh. ; tar. gry. to blk.

Ag-wh., shiny

10.0-12.0

Iso.; scales, wire

F. hackly Duct, and mall.

Au-yel.

Au-yel., shiny

2f-3

15.6-19.3

2 £-3

Iso.; scales, grains

F. hackly Duct, and mall.

Yelh-wh.

Yelh-wh., shiny

12.5-15.5

Iso.; flakes, grains

F. hackly Duct, and mall.

Ag-wh., rdh. hue

Ag-wh., shiny

2 -2*

Hex. rhom.; us. gran.

C. 1, basal, per., sectile, slightly mall.

Sn-wh.

13.61iq. 14. 4 xls.

Vol.

Iso., oct. xls at -39° C. Fig. 1

C. 3, cubic, 90°

Ag-wh.

Ag-wh., shiny

13.7-14.1

Iso., plates, coatings

F. uneven, conch.

SECTION 4.— Continued. Metallic luster;

Name.

Composition.

Mag. or becomes so in r.f. Contains Fe (Cp. the dark micas (below), which sometimes become magnetic

Little or no H2O in c.t.

Strongly mag. before heating

Magnetite

(Magnetic Iron Ore; Lodestone) (See p. 22)

FeFe2O4

(Somet. Mg, Mn, Tl)

Nonmag. or but slightly so before heating

HEMATITE (Specular Iron) (See p. 134)

Fe2O3 (Somet. TI, Mg)

Martite (See p. 134)

Fe2O3

Much H2O in c.t.

Botryoidal, stalactitic, amorphous

Limonite

(Brown Hematite; Bog Iron Ore) (See p.131)

FeO-OH'ttH2O

Prismatic xls.; lepidocrocite scaly

GOETHITE (Lepldocroclte) (See p. 142)

FeO-OH

Rdh-blk. ; st. dark rdhbrn. Us. decrep. violently in c.t.

TURGITE (Hydrohematite) (See p. 144)

FeO-OH, Fe2O3, H2O

Cu globule in r.f. on ch.

Cuprite submetallic luster; Melaconite earthy or in scales (tenorite)

Cuprite

(See p. 141).

Cu2O

Melaconite (Tenorite) (See p. 21)

CuO

Micaceous or foliated

Decomposed by boiling cone. (see p. 236)

Biotite

(Black Mica) (See p. 58)

(A little F, often Tl)

Phlogopite

(Amber Mica) (See p. 106)

(A little F and Fe)

W. reac. after fus. w. soda Mag. w. little soda

Mn in soda bd. (Cp. hiibnerite, p. 234)

Wolframite

(See p. 21)

Little or no Mn reac.

FERBERITE (See p. 21)

(Some Mn)

Cb. reac. after fus. w. borax

Mn in soda bd. Mag. w. little soda

Columbite

(See p. 134)

Mn in soda bd.; U in s. ph. bd.

Samarskite (See p. 133)

fus. 1-5 or vol.; no As, Sb, nor S

Color.

Streak.

Hardness.

Specific Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fracture.

Fe-black

Blk.

Iso.; oct. and dodec. Figs. 1, 7, 8; gran.

P. 4, oct., 701°, 1091° F. conch., uneven

Steel-gry. to Fe-blk.

Dk. red to -red

Hex. rhom.; comp., gran.

F. uneven, splint. P. basal or rhom.

Fe-blk.

Rdh-brn. to purplish-brn

Iso.; us. oct. Fig. 1

F. conch. P. oct.

Dk. brn., blk., yel.

Yelh-brn.

Fibr. ; comp. botryoidal

F. splintery, uneven

Yelh. or redhbrn. to blk.

Yelh-brn.

5 -5J

Orth. ; acic. or

scaly xls.

C. 1, pinac., per. F. uneven

Rdh-blk.

Dk. rdh-brn.

Botry. ; stalac., earthy

F. splintery, uneven, earthy

Deep red

-red

Iso.; comp.

F. uneven

Fe-gry. to blk.

Gryh-blk.

Mon.; earthy, comp., scaly

F. uneven

Blk., brn., grn.

Pearly, submit.

Mon., pseudohex; plates, scales

C. 1, basal, per. Thin flakes very elastic

Yelh-brn., grn.

Pearly, submit.

Mon., pseudohex; plates, scales

C. 1, basal, per. Thin plates very elastic

Dk. gryh-blk. to -blk.

Blk.

Mon. ; us. xls.

C. 1, pinac., per. F. uneven

Blk.

-blk.

Mon.

C. 1, pinac., per. F. uneven

Fe-blk. to -blk.

Dk. red to blk

Orth. ; us. short prism.

C. 1, pinac., poor F. uneven, conch.

Velvet-blk.

Dk. rdh.-

Orth.; us. comp., dissem.

F. conch.

SECTION 4.— Concluded. Metallic luster;

Name.

Composition.

Gel. sil. 'in HC1 sol. on evaporation

Fus. w. much intumes. Insol. in HC1 after fus.

ALLANITE (Orthite) (See p. 71)

(Also LI. Nd, Pr, Y.'etc.)

Strongly mag. after fus. Little intumes

Ilvaite (Llevrite) (See p 22.)

Te minerals. Gently heated in cone H2SO4 gives rdhviolet sol. (See p. 188) (Mn minerals distinguish ed by borax bd. test)

Fusible and wholly vol.

Wh. subl. near assay; grn. flame

Tellurium (See p. 27)

Te

(Somet. Se. Au, Fe)

Ag globule in o.f.

May contain also Au; somewhat sectile

HESSITE (See p. 27)

Ag2Te

(Au Iso. w. Ag)

Au w. soda on Ch. Us. w. some Ag

Slightly sectile to brittle

PETZITE (See p. 14)

Ag3AuTe2

Very brittle; cleavable. Krennerite d o c r e p i - tates violently b.b. and fuses to Au button

SYLVANITE (See p. 26)

KRENNERITE (See p. 27)

Fuses to Au button

Very brittle; uneven to conchoidal fract.

CALAVERITE (See p. 27)

Bi w. soda on ch.

Red subl. on ch. w. von Kobell's flux

Tetradymite

Bi2Te3 (S !so. w. Te)

Pb w. soda on ch.

PbSO4 ppt. w. H2SO4 in HNO3 sol.

Altaite (See p. 28)

PbTe (Some Ag, Au)

Nagyagite

Au, Pb, Sb, Te, S

SECTION 5. Metallic luster;

Strongly mag. before heating. (Cp. platinum, v which i s sometimes mag.)

Completely sol. in HC1; sol. reac. for botb ferrous and ferric Fe. (Cp. ilmenite, below)

MAGNETITE (Magnetic Iron Ore; Lodestone) (See p. 22)

FeFe2O4 (Somet. Mg, Mn, Tl)

Malleable. Meteoric Fe and some terrestrial Fe contains Ni

Iron (Native Iron)

Fe (Us. w. some Nl)

H2O2 test for Ti

Somet. slightly mag.

ILMENITE (Menaccanlte; Titanic Iron) (See p. 22)

(Often also Fe2 Os; somet. Mg)

tr a :„ trri

fus. 1-5 or vol. ; no As, Sb, nor S

Color.

Streak.

Hardness.

Specific Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fracture.

Brn. to pitchblk.

Gry.

5 J-6

2J

Mon.; us. comp.

F. uneven conch.

Fe-blk.

Blk.

Orth. us. prism, xls.

C. 2, pinac. poor, 90°, 60°, 120° F. uneven

Sn-wh.

Sn-wh.

2 -2J

Hex. rhom. ; us., gran., comp.

C. 3, prism., per. Somewhat brittle

Ste'el-gry to Pb-gry.

Gry.

Iso. ; us. comp.

F. uneven

Steel-gry to Fe-blk.

Gry.

2J-3

H

Comp., gran.

F. uneven

Steel-gry to Ag-wh.

Gry.

Mon. ; branching aggregates

C. 1, pinac., per. F. uneven

Ag-wh. to brass-yell.

Gry.

Orth; us. prism., striated

C. 1, basal, per. F. uneven

Pale bronzeyel.

Yelh-gry.

2£

Monocl.; us. comp.

F. uneven, conch.

Pale steel-gry.

Gry.

n

Hex. rhom.; us. bladed

C. basal., per. Laminae flex.

Sn-wh.; tar. bronze-yel.

Gry.

a

Iso. ; us. mass.

C. 3, cubic, 90° F. uneven, sec tile

Dk. Pb-gry.

Dk. Pb-gry.

1 -U

Orth.; us. fol.

C. pinac., per. Laminae flex.

fus. above 5; becomes strongly mag. in r.f.

Fe-blk.

Blk.

5Hh

Iso.; xls., Oct., dodec., Figs. 1,7,8; gran.

P. 4, oct., 70£°, 109£° F. uneven, conch.

Steel-gry.

Steel-gry.

Iso. ; us. mass.

C. cubic F. hackly

Fe-blk.

Blk. to -red

Hex. rhom.; us. plates or mass.

F. conch. P. basal, rhom.

SECTION 5.— Concluded. Metallic luster;

Name.

Composition.

Cr in s.ph. bead

Bead shows Fe reac. while hot and Cr on cooling

CHROMITE (Chromic Iron) (See p. 133)

FeCr2O4 (Mgiso. w.Fe; Aland Fe'" Iso. w. Cr

Mn in soda bd.

Wh. ZnO subl. on intense ign. w. soda on pt wire; grn. w. (Fig. 81, p. 189)

Franklinite

(See p. 23)

(Fe,Zn,Mn)

Not included above

Little or noH2O in c.t.

Sometimes slightly mag. before heating. Dif. fus.

HEMATITE (Specular Iron) (See p. 134)

Fe2O3 (Somet. Tl. Mg)

Martite (See p. 134)

Fe2O3

H2O in c.t. Dif. fus.

Mammillary, botryoidal, stalactitic, amorphous

Limonite

(Brown Hematite; Bog Iron Ore) (See p. 131)

FeO.OH-rzH2O

Us. prisms. ; lepidocrocite scaly

Goethite

(Lepidocrocite) (See p. 142)

FeO-OH

Us. decrepitates violently in c.t.

TUBGITE (Hydrohematlte) (See p. 144)

FeO.OH,Fe2O3,H2O

SECTION 6. Metallic luster;

Little or no H2O in c.t.

O in c.t.

Pyrolusite

(See p. 18)

MnO2 (A little Hz 0)

Slowly sol. in HC1 w. gel. sil.

Braunite (See p. 23)

No gel. sil.

Hausmannite (See p. 131)

Much H2O in c.t.

Prismatic xls., us. striated

MANGANITE (See p. 130)

MnO-OH

Amorphous; us. Ba reac. in HC1 sol. Botry., reniform, stalactitic

Psilomelane

(See p. 22)

MnO2,MnO,H2O, BaO,K2O, etc.

Dull, earthy, frothy, powdery, or reniform and compact

Wad

(Bog Manganese) (See p. 17)

MnO, MnO2,H2O (Often Fe. SI, Al. Ba)

f us above 5 ; becomes strongly mag. in r.f

Color.

Streak.

Hardness.

Specific Gravity.

Crystallization and Structure.

Cleavage and Fracture.

Fe-blk. to -blk

Dk. brn.

Iso. ; gran., comp.

F. uneven, conch.

Fe-blk.

Rdh-brn. to blk.

5Hh

Iso.; gran., comp., oct. xls., Fig. 1

P. oct. F. uneven conch. '

Steel-gry. to Fe-blk. Earthy, red

Cherry-red -red

5Mi

Hex. rhom.; comp., gran.

F. uneven, splint. P. basal, rhom.

Fe-blk.

Purplish or rdh-brn.

Iso. ; us oct. xls. Fig. 1

P. oct. F. conch.

Brn. to blk. Earthy, yel.

Yelh-brn. Yel. ocher

No xls.; us. comp. or fibr., botryoidal

F. splintery, uneven

Dk. brn. to blk.

-yel. to ocheryel.

5 -5J

Orth. ; acic. or scaly xls.

C. 1, pinac., per F. uneven, splintery

Blk to rdh-blk.

-red

5 £-6

Botry., stalac., earthy

F. splintery, uneven, earthy

fus. above 5; not. mag. after r.f.; Mn in borax bead

Fe-blk.

Blk.

Pseudm., gran., columnar

F. splintery, uneven

Dk. -blk. to steel-gry.

-blk.

6 -6£

Tetr.; us. pyram.

C. pyram., per. F. uneven

-blk.

Tetr. ; us. gran. ; pyram. xls.

C. 1, basal F. uneven

Steel-gry. to Fe-blk.

Rdh-brn. to blk.

3M

Orth.; prism., striated

C. 1, pinac., per. F. uneven

Fe-blk.

-blk.

Amor., comp., botry.

F. uneven, conch.

Bluish or -blk. to dull blk.

-blk. to blk.

Amorph., earthy, comp.

F. earthy

'210

SECTION 7. Metallic luster; fus. above 5;

Name.

Composition.

Very soft. Soils fingers and marks paper easily. Greasy feel.

S and Mo reac. in o.t. Yel-grn. flame. Characteristic gnh. streak on porcelain or glazed paper.

MOLYBDENITE (See p. 17)

MoS2

No reac. in o.t. Very refractory b.b.

Graphite

(Plumbago; Black Lead) (See p. 17)

(Often Fe, clay, etc.)

Cr in borax or s. ph. bd.

Mag. on intense ign. w. equal amt. of soda on ch. (except varieties with much Mg and Al)

Chromite

(Chromic Iron) (See p. 133)

FeCr2O4 (Mg Iso. w. Fe; Al and Fe'" Iso. w. Cr)

H2O2 test for Ti after fus. w. soda

Mag. on intense ign. w. equal amt. of soda on ch.

Ilmenite

(Menaccanlte ; Titanic Iron) (See p. 22)

FeTiO3 (Some Fe O and Mg)

Submetallic to adamantine luster; us. prismatic xls.

RUTILE (See p. 72)

TiO2

(Us. a little Fe)

Similar to Rutile. Disting. by xl. habit and phys. properties. Brookite us. tabular xls.

Octahedrite (Anatase) (See p. 68)

TiO2

Brookite (See p. 72)

TiO2

Ca reac. in HC1 sol. after fus. w. soda and precipitating Ti w. am.

Perovskite (Perofsktte) (See p. 91)

CaTiO3 (Fe Iso. w. Ca)

Cb. reac. after fus. w. soda or borax, dissolving in HC1, and boiling w. Sn.

W. little soda becomes mag. ; us. Mn reac. also

Columbite

(See p. 134)

(Ta Iso. w. Cb; a little Sn. andW)

Tantalite (See p. 134)

(Cb Iso. w. Ta; slight Sn and W)

Disting. by st. and dull exterior, brilliant on fresh fracture

Fergusonite (See p. 133)

(Y,Er,Ce,U)

TJ in s. ph. bd. Little or no Cb

Very heavy; sol. in dil. H2SO4 w. slight evolution of gas (He)

URANINITE (Pitchblende) (See p. 22)

Uranate of Pb and U (Also Th, La, Y, C'a. X, lie, A, and us. H2 O)

Pt or metals of the Pt group

Malleable; b.b. unaltered; sometimes mag.

PLATINUM (See p. 29)

Pt

(Us. w. Fe, Pd, Rh, Tr, Os)

Slightly malleable to brittle; Os in o.t.

Iridosmium (Osmlrldlum) (See p. 29)

Ir.Os

(Somet. Rh, Pt, Tlu)

1 No reac. for Os

Iridium (See p. 29)

Ir

(W. Pt, Pd, Rh)

not. mag. after r.f . ; no Mn in borax bead

Color.

Streak.

Hardness.

Specific Gravity.

Crystallization and Structure.

Cleavage and Fracture.

Pb-gry.

Gryh-blk., . on glazed paper

1 -H

Hex. (?); foliated, scaly

C. 1, basal, per.; thin flakes, flex. Sectile

Fe-blk. to dk. steel-gry.

Gryh-blk.

Hex. rhom.; foliated, earthy

C. 1, basal, per.; thin flakes, flex.

Fe-blk. to -blk.

Dk. brn.

Iso.; us. gran., comp.

F. uneven, conch.

Fe-blk.

-red to blk.

Hex. rhom.; , us. plates or gran.

F. conch. P. basal, rhom.

Rdh-brn. to blk. and yelh.

Pale brn. to gry.

G -7

Tetr. ; us. xls. ; twins

C. 2, prism F. uneven

Brn. to dk. blue and blk.

Wh.

Tetr. ; us. pyram., tabular

C. 5. basal and pyram, 82°, 111°, 136|° F. uneven

Hair-brn to blk.

Wh. to gryh. or yelh.

5 £-6

Orth. ; us. xls. often pseudohex.

F. uneven

Yel. and brn. to blk.

Wh. to gryh.

5 §-6

Iso., cubes, Fig. 5; striated; dissem.

C. 3, cubic, 90° F. uneven

Fe-blk. to gryh. and -blk.

Dk. red to blk.

Orth.; short prism, xls.

F. uneven, conch. C. 1, pinac., poor

Blk.

Blk.

6 . 5—7 . 3

Orth.; short prism, xls.

F. conch., uneven C. 1, pinac., poor

-blk

Pale brn.

Tetr.; us. comp.

F. uneven

Gryh., ., or -blk.

-blk.

Iso.; us. botry., comp., gran.

F. conch.

Whh. steel-gry.

Gry., shiny

4 -4J

Iso. ; us. grains or scales

F. hackly mall., duct.

Sn-wh. to It. steel-gry.

Gry.

18.9-21.2

Hex. rhom.; us. flat grains

C. 1, basal, per. F. uneven

Ag-wh., tinge of yd.

Gry.

22 . 6-22 . 8

Iso.; angular grains

F. hackly; somewhat mall.

SECTION 8. Nonmetallic luster;

Name.

Composition.

Burns w. blue flame and fumes

Subl. in c.t. is red liquid while hot, yel. solid when cold

Sulphur

(See p. 94)

S

(Traces Te, Se. As; often clay, bitumen, etc.)

As2O3 subl. on ch. ; wh. xln., vol.; far from assay

Subl. in c.t. deep red, nearly blk. when hot; a rdh-yel. transp. solid when cold Orpiment, thin flakes flexible

REALGAR (See p. 136)

AsS (Slightly sectlle)

ORPIMENT (See p. 136)

As2S3

Vol. on ch. ; As2O3, subl. in c.t.

Arsenolite

As203

Sb2O3 subl. on ch.; dense wh. and near assay

SO2 in o.t.

Kermesite

Sb2S20

Easily fus. in c.t. w. slight wh. subl.

Senarmontite (See p. 49)

Sb2O3

Hg subl. in c.t. w. dry soda

SO2 and Hg in o.t.; blk. subl. in

c.t.

Cinnabar

(See p. 137)

HgS

(Us. w. Fez Os, clay, bitumen)

Cl reac. w. AgNO3 after soda fus.

Calomel (See p. 47)

Hg2Cl2

K or Na flame color; sol in H2O

Alkaline residue after ign. ; wholly vol. only by prolonged heating

See Section 15, p. 224)

Str. Fe - black to black

Burns w. pale feeble flame

ANTHRACITE COAL (Hard Coal) (See p. 19)

C,H,O, etc. (C 85-95%)

Str. blk. to - blk.

Smoky yellow flame

BITUMINOUS COAL (Soft Coal) (See p. 19)

C,H,O, etc.

(C 76-88%)

Str. brown to bnhblk.

Smoky yellow flame

LIGNITE (Brown Coal) (See p. 128)

C,H,O, etc.

(C 65-76%)

Str. b n h - b 1 k. Sticky when plastic

Bright flame and pitchy odor

ASPHALT (Mineral Pitch) (See p. 17)

C,H,O, etc.

Str. wh. Electrified by friction

Dense wh. aromatic fumes on ign.

AMBER (Succinite) (See p. 95)

C20H3202

Str. bnh-yel., pale yel. Plastic

Smoky yel. flame, paraffin odor. Somet. sticky

OZOCERITE (Native Paraffin) (See p. 128)

CnH2n+2

easily vol. or combustible

Color.

Luster

Hardness.

Specific Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fracture.

Pale yel. to . and -yel.

Resinous

Orth.; Figs. 34, 35 gran., comp.

F. conch.

Aurora-red and orange-yel.

Resinous

1J-2

Mon.; gran, dissem.

C. 1, pinac. F. conch.

Lemon-yel.

Resinous C. pearly

Mon.; us. fol.

C. pinac., per.; striated; flex.

Cols, to wh.

Vitreous or silky

U

Iso.; us. capil.

F. uneven

Cherry-red to -red

Adamantine

i -u

Mon.; us. acic.

C. pinac., per.

Cols, to wh. and gryh.

Resinous

[so., oct. Fig. 1; gran.

F. uneven

Cochineal-red to .

Adamantine

Vol.

Hex. rhom. ; gran., earthy

C. 3, prism., per., 60°, 120° F. uneven

Cols., wh., or gry.

Adamantine

1 -2 '

Vol.

Tetr.; xls., coatings

F. conch. Sectile

Fe-blk. to blk.

Vitreous, submit.

1 . 3-1 . 7

Amorph.

F. conch.

Blk. to bnh-blk.

Pitchy, dull

2 -2J

Amorph.

F. cubical, conch.

Bnh-blk to blk.

Dull

2 -2J

Amorph., often woody

F. conch., splint.

Blk. to bnh-blk.

Pitchy, dull

Amorph.

F. conch.

Yel., bnh., whitish

Greasy, resinous.

Amorph.

F. conch.

Bnh-blk., yel., grn.

Waxy, greasy, submit.

Amorph.

F. uneven

SECTION 9. Nonmetallic luster; fus 1-5;

Name.

Composition.

CO-2 efferv. in warm dil. acids

In c.t. dark yel. while hot; decrepitates

CERUSITE (See p. 51)

HC1 sol. w. BaCl2 gives wh. ppt. BaSO4; slightly sectile

Leadhillite (See p. 31)

S. reac. in fus. w. soda; sol. in dil. HC1; PbCl2 ppt. on cooling

Little or no H2O in c.t. ; decrepitates

ANGLESITE (See p. 40)

PbS04

Canary-yel. powder; ferric Fe and Cu in HC1 sol.

Beaverite (See p. 135)

HNO3 sol. reacts for P w. am. mol.

In c.t. slight wh. subl. PbCl2

PYROMORPHITE (See p. 122)

(Often also Ca and As)

As subl. in c.t. w. ch.

%

Wh. ppt, AgCl w. AgNO3 in HNO3 sol.

(See p. 97)

(Often also Ca and P)

V in s. ph. bead

Wh. ppt. AgCl w. AgNO3 in HNO3 sol.

VANADINITE (See p. 96)

(Somet. P and As)

H2O in c.t. Reacts for Zn. Cuprodescloizite contains Cu

DESCLOIZITE (Cuprodesciolzlte) (See p. 140)

(Somet. Cu, As)

Cr in s. ph. bead

Streak orange-yel. Decrepitates on ign.

CKOCOITE (See p. 139)

Mo in s. ph. bead

Streak white. Decrepitates on ign.

Wulfenite

(See p. 96)

PbMoO4 (Ca somet. Iso. w. Pb)

SECTION 10. Nonmetallic luster; fus. 1-5;

Deep red color (Hydrocuprite orange)

Strong sol. in HC1 gives wh. ppt. CuCl when much diluted (a cuprous compound)

Cuprite

(Hydrocuprite) (See p. 141)

Cu2O (GH In hydrocuprlte)

CO2 efferv. in HC1

H2O in c.t. Disting. by color

MALACHITE (See p. 147)

/

Azurite

(See p. 147)

Blue flame col.

H2O in c.t.

Atacamite

(See p. 147)

Pb globule w. soda and ch. on ch.

Color.

Luster.

Hardness.

Specific Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fracture.

Cols, to wh. and gry.

Adamantine

3 -3fc

Orth.; pseudohex.

F. conch.

Cols., wh., yel., grn., or gry.

Resinous C. pearly

2f

H

Mon.; us. tab.; comp.

C. 1, basal, per. F. uneven, conch.

Cols., wh., yelh., .

Adamantine to vitreous

Orth.; us. xls.

C. 3, basal and prism. 76°, 90° F. conch.

Canary-yel.

Dull

Hex.; microscopic plates

F. earthy

Grn., yel., brn. and wh.

Resinous

3M

Hex.; us. prism.

F. uneven conch.

Cols, yel., orange, brn.

Resinous

H

Hex.; prism.; crusts

F/ uneven

Ruby-red, brn., yel.

Resinous

U

Hex.; us. prism. ; Fig. 49

F. uneven, conch.

-blk. .to red

Greasy

U

Orth.; us. xls.; drusy

F. uneven, small conch.

Bright red

Adamantine to vitreous

u

Mon.; us. prism.

C. 2, prism., 86° F. uneven, conch.

Yel., orangered, gry., wh.

Resinous to adamantine

Tetr.; square tab.

C. pyram. F. uneven* conch.

Cu globule w. soda and ch. on ch.

Ruby-red to rdh-blk. (Orange)

Adamantine to earthy

3 J-4

Iso.; comp. (Hydrocuprite earthy)

F. uneven

Bright grn.

Vitreous, silky, or dull

3M

Mon.; us. ' bo try., incrusting.

C. 1, basal, per. F. conch., splint.

Azure-blue

Vitreous

Mon.; us. xls.; incrust.

C. 2, domal, 29° F. conch.

Emerald-grn.

Adamantine to vitreous

Orth.; us. prism.

C. 1, pinac., per. F. conch.

SECTION 10. Concluded. Nonmetallic luster;

Name.

Composition.

S reac. in fus. w. soda (Compare Covellite, p. 200)

Much H2O in c.t. Sol. in H2O Plates moist Fe with Cu

CHALCANTHITE (See p. 16)

CuSO4-5H2O

Acid H2O on intense ign. in c.t. Insol. in H2O

BKOCHANTITE (See p. 147)

Canary-yel. powder; ferric Fe and Cu in HC1 sol.

Beaverite (See p. 135)

Deflagrates on ch.; As fumes on ch. ; As mirror w. ch. in c. t.

Globule xln. after fus.; little H2O at red heat

Olivenite (See p. 146)

Decrep. and gives much H2O in c.t. ; res. of olive-grn. scales

Chalcophyllite

10H2O

SECTION 11. Nonmetallic luster; fus. 1-5;

Ag globule, brittle if containing Sb. SO2 fumes and wh. subl. of As2Oa or Sb2Oa in c.t. (Cp. polybasite)

Abund. subl. in c.t., deep red hot, rdh-yel. cold; slight S subl. above it

PKOUSTITE (Ruby Silver) (See p. 137)

Ag3AsS3 (Somet. Sb)

Slight subl. in c.t., blk. hot, redbrn. cold; slight S subl. above it

PYRARGYRITE (Ruby Silver; Dark Ruby Silver) (See p. 129)

Ag3SbS3 (Somet. As)

Mall. Ag globule; Cl, Br, or I reac. w. powdered galena in c.t.

Subl. wh. both hot and cold. Highly sectile mineral

CERAKGYKITE (Horn Silver) (See p. 46)

AgCl (Somet. Hg Iso. w. Ag)

Subl. yel. hot, wh. cold. Not disting. by bp. methods. Sectile

EMBOLITE (See p. 93)

Bromyrite (See p. 95)

Subl. orange-red hot, lemon-yel. cold. Sectile; flakes flex.

lodyrite (See p. 136)

Agl

Brittle Bi globule; red subl. w. von Kobell's flux

CO2efferv.inHCl; H2Oinc.t.

Bismutite

fus. 1-5; Cu globule w. soda and ch. on ch.

Color.

Luster.

Hardness.

Specific Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fracture.

Deep azureblue

Vitreous

Tri.; xls., crusts stalac.

F. conch.

Deep emerald prn.

Vitreous

Orth. ; us. xls.

C. 1, pinac., per. F. uneven

Canary-yel.

Dull

Hex.; microscopic plates

F. earthy

-grn. to olive-grn. and brn.

Vitreous to adamantine

3

2-2 £

Orth.; prism., fiber, crusts

F. conch, to uneven

Grass-grn.

Vitreous; C. pearly

2-2 £

Hex. rhom.; us. tab.

C. basal, per.

Ag-wh. globule w. soda and ch. on ch.

Scarlet to ruby-red St. scarlet

Adamantine

2 -2£

Hex. rhom. hemimor. ; comp.

C. 3, rhom., poor, 72° F. conch.

Dk. red to blk. St. purplish

Metallic adamantine

Hex. rhom. hemimor. ; comp., dissem.

C. 3, rhom., poor, 72° F. conch., uneven

Pearl-gry. and . to cols.

Resinous to adamantine

1 -H

Iso.; us. wax-like crusts

F. uneven Sectile

Grn. or yel.

Resinous to adamantine

1 -H

Iso. ; us. comp.

F. uneven Sectile

Grn. or yel.

Resinous to adamantine

Iso.; us. comp.

F. uneven Sectile

Yel. to . and .

Resinous to adamantine

1 -H

Hex. hemimor. ; prisms, scales

C. 1, basal, per. Sectile Thin flakes flex.

Wh., grn. yel., gry.

Dull

4 -4*

H

Amorph., earthy

F. earthy

SECTION 12. Nonmctallic luster; f us. 1-5; no metal on

Name.

Composition.

CO2 efferv. in hot HC1

Decrepitates; becomes blk. and mag. in c.t.

Siderite

(Spathic Iron) (See p. 41)

FeCO3 (Mg, Mn. Ca Iso. w. Fe)

Dif. fus.; strongly mag. after heating in r.f.

Little or no H2O in c.t. ; st. red

HEMATITE (See p. 134)

Fe203 (Somet. Tl and Mg)

Martite (See p. 134)

Fe203

H2O in c.t. Earthy, mammillary, stalactitic

Limonite

(Brown Hematite) (See p. 131)

FeO-OH-nH2O

Us. prismatic xls. H2O in c.t. Lepidocrocite scaly

GOETHITE (Lepidocrocite) (See p. 142)

FeO-OH

Us. decrepitates in c.t. H2O in c.t.

TURGITE (Hydrohematlte) (See p. 144)

Sol. in cold HoO; wh. ppt. BaSO4 w. BaCl2 in HC1 sol. Acid H2O in c.t. The ferric salts give ppt. in boiling water

Ferrous iron only; yelh. on exposure. Sweetish astringent metallic taste

MELANTERITE (Copperas) (See p. 120)

FeSO4-7H2O

(Mg and Mn Iso. w. Fe)

Ferric iron only. Disagreeable metallic taste

Copiapite

(See p. 76)

(Often Al.Mg)

Ferric Fe only; K flame; little H2O in c.t.

Jarosite

(NI Iso. w. K)

P reac. w. am. mol. Much ferrous Fe

Mn in borax bd. Little or no H2O in c.t.

Li flame. (Cp. lithiophilite, p. 228)

Triphylite

(Mn Iso. w. Fe)

F reac. w. KHSO4

Triplite

(R Fe, Mn, Ca. Mg)

Little or no Mn

Whitens w. gentle heat in c.t.

(See p. 104)

P reac. w. am. mol.

Ferric Fe

H2O in c.t.

Dufrenite

As subl. in c.t. w. ch. fragment

HC1 sol. rose-red; Co in borax bd. after roasting (Cp. annabergite, below)

ERYTHRITE (Cobalt Bloom) (See p. 137)

(Nl, Fe, Ca Iso. w. Co)

HC1 sol. grn.; Ni in borax bd., after roasting (Co may mask bd. reac. for Ni)

Annabergite

(Nickel Bloom) (See p. 120)

(Co Iso. w. Nl)

HC1 sol. yel; rdh-brn. ppt. w. am.; ferric but no ferrous Fe

Scorodite

(See p. 122)

FeAsO4-2H2O

ch. ; mag. after r.f . ; sol. in HC1 without res. or gel. sil.

Color.

Luster.

Hardness.

Specific Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fracture.

Lt. to dk. brn. and gry.

Vitreous; C. pearly

3M

4H>

Hex. rhom.; gran., comp.

C. 3, rhom., per., 73° F. uneven

- red to

blk.

Dull

5J-61

5 -5£

Hex. rhom.; earthy; reniform

F. uneven to splint.

Fe-blk.

Submetallic to dull

Iso.

P. 4 oct., 70°, 109|° F. conch.

Yelh-brn to dk. brn

Silky or dull

Fibr., bo try., earthy

F. splint., uneven

Yclh- or redhbrn. to blk.

Adamantine to dull

5 -5*

Orth.; acic. or scaly

C. 1, pinac., per. F. uneven, splint.

Rdh-blk. St. dk. redhbrn.

Dull, silky to submetal.

Botry., incrust., stalac., earthy

F. splint., uneven, earthy

Apple-grn to wh.

Vitreous

Mon.; capil., fibr., comp.

C. 1, basal, poor F. conch., earthy

S-yel.

Pearly

4H>

Mon.; us. gran, scales

C. 1, pinac. F. uneven

Ocher-yel. to clove-brn.

Vitreous

2Hh

Hex. rhom.; us. xls.

C. 1, basal , F. uneven

Lt. blue, grn. or gry.

Vitreous to resinous

4H>

H

Orth.; us. comp.

C. 2, basal, per. and pinac.

Chestnut-brn. to -brn

Resinous

Mon.; us. comp.

C. 2, at 90° F. uneven

Blue, bluishgrn. to cols.

Vitreous; C. pearly

1J-2

Mon.; earthy, radial

C. 1, pinac., per. F. splint., earthy

Dull olive to -grn.

Silky, weak

8M

Orth. us. fibr.

F. splint.

Crimson to peach-red

Dull; vitreous; C. pearly

Mon.; us. earthy, acic.

C. 1, pinac., per.; sectile Thin flakes flex.

Apple-grn.

Vitreous

1 -2*

Mon.; us. earthy, capil.

F. uneven

Pale grn or brn.

Vitreous

3H

Orth.; us. xls.

F. uneven conch.

SECTION 13.— Nonmetallic luster; fus. 1-5; no metal

Name.

Composition.

Micaceous, foliated, or scaly. Thin flakes tough and elastic

Gel. sil. w. HC1 on evaporation

Lepidomelane

Slightly sol. in HC1 w. separation of SiO2

Biotite

(Black Mica) (See p. 58)

Gel. imperfectly; iso.

xls.

Mostly ferric Fe

ANDRADITE (Ca-Fe Garnet) (See p. 102)

(Fe, Mn. Mg, Iso. w. Ca; Al Iso. w. Fe)

Gel. after fus. but not before

Partly decomp. by HC1

GLAUCONITE (Greensand) (See p. 11 9)

approx. (Some Al; Mg)

Gel. ; much ferrous Fe

May be mag. from included magnetite

Fayalite (See p. 85)

Fe2SiO4 (Some Mn, Mg)

Gel. sil. w. HC1; both ferrous and ferric Fe

Fuses quietly

Ilvaite (Llevrlte) (See p. 22)

Fus. w. intumes

ALLANITE (Orthlte) (See p. 71)

(OH)(SiO4)

(Some La, Nd. Pr. Y. etc.)

H2S and gel. sil. w. HC1

ZnO subl. on ch. w. soda; grn. w. (See p. 189)

Danalite

(K Mn, Fe, Zn)

SECTION 14. Nonmetallic luster; fus. 1-5

Micaceous; thin flakes tough and flex, or elastic

Easily fus. ; Li flame

Zinnwaldite

Dif. fus.

Biotite

(Black Mica) (See p. 58)

Red; isometric

Sol. in HC1 w. gel. after fus.

ALMANDITE (Fe-Al Garnet) (See p. 101)

(Mn, Mg, Ca Iso. w. Fe)

Fus. quietly or w. little intumes. to shiny blk. glass

(Concluded on next page)

Little or no Al. Diallage, lamellar to fibr., w. pearly to metalloidal luster

Pyroxene

(Diallage) (See p. Ill)

Hedenbergite (See p. Ill)

(Some Mg)

on ch. ; mag. after r.f . ; sol in HC1 w. gel. or granular sil.

Color.

Luster.

Hardness.

Specific. Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fracture.

Blk. to -blk.

Adamantine to pearly

4H>

Mon., 6-sided plates

C. 1, basal, per.; elastic

Grn. to . or -blk.

Splendent ; C. pearly

Mon., often 6-sided

C. 1, basal, per.; elastic

Wine-red, ., yel., brn., to blk.

Vitreous to resinous

Iso.,dodecahedron and trapezohedron common

F. uneven to conch.

Yelh-grn. to gryh. and -grn.

Vitreous, dull

Amor ph., gran., earthy

F. earthy, uneven

Yel. to dark yelh-grn. and blk.

Metalloidal, resinous

Orth.; tabular, comp.

C. 2, pinac., 90° F. uneven

Fe-blk.

Submetallic

5£-6

Orth.; us. prism, xls.

C. 2, pinac., poor, 90° F. uneven

Brn. to pitchblk.

Resinous to submetallic

2§

Mon.; us. comp.

F. uneven, conch.

Flesh-red to gry.

Vitreous to resinous

Iso. tetrh. ; us. comp.

F. uneven

no metal on ch. ; mag. after r.f. ; insol. in HC1

Gry., yel., brn., violet

Pearly

2H?

Mon., 6-sided plates

C. 1, basal, per.; flex.

Grn. to . or -blk.

Splendent C. pearly

Mon., 6-sided plates

C. 1, basal, per.; elastic

Deep red to -blk.

Vitreous

Iso., dodecahedrons and trapezohedrons common

F. uneven to conch.

Lt. to dk. grn.

Vitreous

Mon.; us. xls., Figs. 40, 41

C. 2, prism., poor, 87° F. uneven

Grn-blk. to blk.

Vitreous

Mon. xls. Figs. 40, 41

C. 2, prism., poor, 87° F. uneven

SECTION 14.— Concluded. Nonmetallic luster; fus

Name.

Composition.

Fus. quietly or w. little intumes. to shiny blk. glass. — Concluded.

Often Na flame. Contains Al and ferric Fe

Augite

(See p. 62)

(Alto 15-20%; somet. Mn. Na)

HORNBLENDE (See p. 61)

(Al to 10-18%, Na, and often H, F)

Na flame; fus. quietly

Prism and cl. angles near 90°

Aegirite (Acmlte) (See p. 63)

Quietly and dif. fus.

Us. bronzy, metalloidal luster; prism and cl. angles near 90°

HYPERSTHENE (See p. 59)

Prism and cl. angles 54° and 126°; Fe chiefly ferrous; sometimes fibrous (asbestos)

Anthophyttite (Asbestos in part) (See p. 62),

(Somet. also Al)

Fus. w. intumes.

Fused mass dk. brn. or blk. ; gel. w. HC1 after fus.

Epidote

(Plstaclte) (See p. 79)

Pyroelectric. Prismatic xls. w. curved triangular cross section

Tourmaline

(Schorl) (See p. 74)

R Mg, Fe, Ca. Na, K, LI (Often a little F)

Fus. w. intumes ; Na flame

Prism and cl. angles 54° and 126°; Fe chiefly ferrous

Arfvedsonite

(Some Al, Fe'")

Both ferrous and ferric Fe, us. fibrous

CROCIDOLITE (See p. 148)

NaFe"/(Fe'/,Mg)

Fus. w. difficulty H2O in c. t. on intense ign.

Rosettes; foliated; thin scales

Chloritoid (See p. 60)

H2FeAl2Si07 (Some Mg, somet. Mn)

Oblong shining scales and plates

Ottrelite (See p. 60)

Si2O9

W reac. after fus. w. soda. Very heavy

Mn in soda bd.

WOLFRAMITE (See p. 21)

Little or no Mn reac.

FERBERITE (Seep. 21)

(Some Mn)

1-5; no metal on ch.; mag. after r.f. ; insoi. in IIC1

Color.

Luster.

Hardness.

Specific Gravity.

Fusibility.

Crystallization and Structure.1

Cleavage and Fracture.

Gnh-blk. to blk.

Vitreous

Mon. xls. Figs. 40, 41 gran, colum.

C. 2, prism., poor, 87° F. uneven

Gnh-blk. to blk.

Vitreous to pearly

Mon. prism, xls., gran.

C. 2, prism., per. 56° F. uneven, splint.

. to - blk.

Vitreous

Mon.; prism.

C. 2, prism. F. uneven

-blk. to brn. and bronze

Pearly to bronzy

Orth. ; us. mass.

C. 2, pinac. per. F. uneven

Gry. clove-brn., grn.

Vitreous C. pearly

Orth. ; us. fibr. or mass.

C. 2, prism, per.

Yelh. to -grn and gry.

Vitreous

Mon.; us. prism.

C. 1, basal, per. F. uneven

Blk., brn., grn.

Vitreous to resinous

Us. 3

Hex. rhom. hemimor. Fig. 58

F. conch., uneven

Blk.; st. dk. bluish-gry.

Vitreous

Mon.; us. prism.

C. 2, prism., per. F. uneven

Leek-grn. to deep lavenderblue

Silky, dull

3£

Fibrous

Fibrous

Dk. gry., grn., gnh-blk.

Pearly

Tri., us. foliated or scaly

C. 1, basal, per. Brittle

Gnh-gry., blk

Vitreous

Tri., oblong scales

C. 1, basal, per. Brittle

Gryh. to - blk.; st. blk.

Submetallic

5-5 £

Mon. ; us. xls

C. 1, pinac. per. F. uneven

Blk. St. -blk

Submetallic

Mon., us. xls.

C. 1, pinac. per. F. uneven

SECTION 15. Xonmetallic luster; fus. 1-5; no

Make flame tests below with Pt wire. Most minerals give some yellow color to the flame after

yellow. The violet flame of K is purplish-red

Name.

Composition.

Wh. AgCl ppt. w. HNO3 sol. and AgNO3

Wh. BaSO4 ppt. K flame in H2O sol. w. HC1 and BaCl2.

KAINITE (See p. 39)

KMgClSO4-3H2O

bitter, astrin- Na flame; gent taste salty taste

Hanksite

9Na2SO4-2Na2CO3- KC1

Intense Na flame; no S; salty taste

Halite

(Rock Salt; Common Salt)

(See p. 39)

(Us. also Ca and Mg)

K flame, Little or no H2O in no S c.t. ; salty, bitter

SYLVITE (iSee p. 39)

Kc1

(Xa Iso. w. K)

Much H2O in c.t.; bitter taste; absorbs moisture

CARNALLITE (See p. 47)

KMgCl3-6H2O

CO2 efferv. w. HC1. H2O sol. gives alkaline reac. w. turmeric paper

Sol. in H2O of xln. if gently heated in c.t. (H2O 63%) Alkaline taste

Natron (Sal Soda)

Na2CO3-10H2O

H2O and CO2 when gently heated in c.t. ; alkaline taste

TKONA (See p. 32)

H2O in c.t. ; partly sol. in H2O

Gay-Lussite

Sulphates.— H2O sol. w. HC1 and BaCl2 gives wh. ppt. BaSO4

Much H2O in c.t.; fine powder sol. in 500 parts H2O; Ca flame

Gypsum

(Selenlte) (See p. 30)

CaSO4-2H2O

Na flame; little or no H2O in c.t.

THENARDITE (See p. 31)

Na2,SO4

B.b. swells and gives K flame; H2O sol. w. HC1 and am. gives gel. ppt. of

Kalinite (Potash Alum)

Mg reac. w. on ch. Bitter salty taste

EPSOMITE (Epsom Salt) (See p. 49)

MgSO4-7H2O

Intense Na flame; much H2O in c.t.

MlBABILITE (Glauber Salt) (See p. 48)

Na2SO4-10H2O

Nitrates. — Deflagrate on ch. ; NO2 fumes w. KHSO4 in c.t. (Concluded next page)

Intense Na flame; cooling salty taste

Soda Niter

(See p. 48)

metal on ch.; not mag. after r.f.; alk. after ign.; sol. in water

being handled, but those containing Na as an essential constituent give an intense and persistent when seen through dark blue glass.

Color.

Luster.

Hardness.

Specific Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fracture.

Cols., wh. to redh.

Vitreous

U-2

Mon.; comp., gran.

C. 3, pinac. and prism., 39|°, 101°

Cols., wh. to yelh.

Vitreous

Hex.; us. xls.

C. 1, basal F. uneven

Cols., wh., redh., bluish

Vitreous

U

Iso. ; us. cubic, Fig. 5; gran., comp.

C. 3, cubic, per., 90° F. conch.

Cols., wh., redh., bluish

Vitreous

U

Iso.; cubes, Fig. 5; gran.

C. 3, cubic, per., 90° F. conch.

Cols., wh., redh.

Vitreous to greasy

i-H

Orth. ; us. mass.

F. conch.

Cols., gry., wh., yelh.

Vitreous

1 -U

Mon.

C. 1, basal F. conch.

Cols., gry., wh., yelh.

Vitreous

Mon.; incrusting

C. 1, pinac.,, per. F. uneven

Cols., wh., yelh., gryh.

Vitreous

H

Mon., us. xls.

C. 2, prism., per., 111° F. conch.'

Cols., wh., yel., red, gray

Vitreous C. pearly

1J-2

Mon.; Figs. 38, 39; gran., comp.

C. 3, prism, and pinac., per., 90°, 66°, 114° F. splint.

Cols., wh., .

Vitreous

Orth.; xls.; cross-twins

C. 1, basal F. uneven

Cols, or wh.

Vitreous

2 -2£

Iso. pyr.; us. fibr.

F. conch.

Cols, or wh.

Vitreous; earthy

2 -2£

Orth.; us. fibr., gran.

C. 1, pinac., per. F. conch.

Cols, or wh.

Vitreous

U-2

H

Mon.; us. cnists, mealy efflores.

C. 1, pinac., per. F. conch.

Cols, or wh.

Vitreous

Hex. rhom. ; us. incrust., gran.

C. 3, rhom., per., F. conch.

SECTION 15.— Concluded. Nonmetallic luster; fus. 1-5; no

Name.

Composition.

Nitrates — Concluded

K flame ; cooling salty taste

Niter

(Saltpeter) (See p. 48)

Kno3

H2O in c.t.; deliquescent before ign.; taste bitter

Nitrocalcite

B reac. w. turmeric paper

Swells and fus. to clear glass; taste sweetish alkaline

BORAX (Seep. 30)

Na2B4O7-10H2O

SECTION 16. Nonmetallic luster; fus. 1-5; no metal Make flame tests below with Pt wire and HC1.

CO2 efferv. in dil. HC1

No H2O in c.t.; Ba flame

Witherite

(See p. 51)

H2O in c.t. ; alkaline sol. in boiling H20

Gay-Lussite

S reac. w. powdered ch. and soda on ch.

Much H2O in c.t. Readily sol. in hot. dil. HC1 (Cp. anhydrite, below)

Sol. in 500 parts H2O; Ca flame; flakes flex.

Gypsum

(Selenlte; Alabaster) (See p. 30)

CaSO4-2H2O

K flame; Mg reac. w. Na phosphate; slight bitter astringent taste

Polyhalite (See p. 78)

2H2O

Little or no H2O in c.t. A nhydrite somet. much H2O; distinguish b y H

Na flame; sol.inHCl; salty taste

Glauberite (See p. 31)

No flame col. ; slowly sol. in hot dil. HC1

Anhydrite

(See p. 40)

Sr flame; nearly insol. in HC1

Celestite

(See p. 40)

SrSO4 (Somet. Ca and Ba)

Ba flame; nearly insol. in HC1 Decrepitates

Barite

(Heavy Spar) (See p. 39)

BaSO4 (Somet. Ca and Sr)

F reac. w. KHSO4 and

glass in c.t.

Little or no H2Oinc.t.

Na flame; easily fus.

Cryolite

(See p. 49)

Na3AlF6

Ca flame ; often phosphoresces and decrepitates in c.t.

Fluorite

(Fluor Spar) (See p. 116)

CaF2 (Somet. Cl Iso. w. F)

metal on ch.; riot mag. after r.f.; alk. after ign.; sol. in water

Color.

Luster.

Hardness.

Specific Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fracture.

Cols, or wh.

Vitreous; silky

Orth. ; us. crusts, acic.

C. 2, prism., per., 70° F. uneven

Wh. or gry.

Silky

Fibrous, efflores.

Fibrous

Cols., wh., gryh.

Vitreous to resinous

2 -2J

1-1*

Mon.; us. comp.

C. 1, pinac., per. F. conch.

onch.; not mag. after r.f .; alk. after ign. ; insol. in water

Cols., wh., yelh., gryh.

Vitreous

Orth. twinned pseudohex.

F. uneven

Cols., wh., yelh., gryh.

Vitreous

Mon.; us. xls.

C. 2, prism., per., 111°

Cols., wh., yel., red, gry.

Vitreous C. pearly

Mon., Figs. 38, 39; gran., comp.

C. 3, prism., pinac., per., 90°, 66° F. conch., splint.

Brick-red to yel. and wh.

Vitreous to resinous

Mon.; fibr., lam el.

C. 1, pinac. F. splint,

Cols., wh., yelh., gryh.

Vitreous

l*-2

Mon.; us. tab. and xls.

C. 1, basal, per. F. conch.

Cols., wh., blue, gry., red

Vitreous; basal cl., pearly

3 -3£

Orth.; us. mass.

C. 3, pinac., per., 90°

Cols., wh., blue, red

Vitreous to pearly

Orth., Fig. 37 xls., fibers

C. 3, basal, per. and prism., 76°, 90°

Cols., wh., blue, yel., red, brn.

Vitreous to pearly

Orth., xls., comp. lamellar

C. 3, basal, per. and prism., 78£°, 90°

Cols., wh., .

Vitreous to greasy

|Mon.; us. gran., comp.

F. uneven P. 3, often, 88°, 90°

Cols., violet, blue, grn., yel., pink

Vitreous

Iso.; us. cubes, Fig. 5

C. 4, oct., per., 70£°, 109|° F. uneven

SECTION 17. Nonmetallic luster; f us. 1-5; no metal on ch.; not

Name.

Composition.

H2S efferv. in hot HC1

Wh. ZnO subl. after intense ign. w. soda on Pt. wire; subl. grn. w. Co (NO 3) 2 (See p. 189)

Sphalerite

(Zinc Blende) (See p. 88)

ZnS (Fe, Mn, Cd Iso. w. Zn)

Wurtzite (See p. 130)

ZnS (Some Fe)

P reac. w. am. mol.

Slight F reac w. KHSO4 in c.t.

CaSO4 ppt. w. H2SO4 in HCl-sol.

No H2O in c.t.

Apatite

(See p. 98)

(Cl Iso. w. F)

A little H20; HF vapor in c.t.

Herderite

Mn in soda bd.

Li flame

(Cp. triphylite),p.218

Lithiophilite

(Fe Iso. w. Mn)

H2O in c.t.

No flame color

Purpurite

U in s. ph. bd.

CaSO4 ppt. w. dil. H2SO4 in HC1 sol.

Autunite (See p. 138)

8H2O

B reac. w. turmeric paper

Na flame

Swells; sol. in H2O

BORAX (See p. 30)

Na2B4O7-10H2O

Ca reac. w. am. oxalate

Ulexite

(Boronatrocalclte) (See p. 46)

NaCaB5O9-8HO

B flame

No H2O in c.t.; Cl reac. after fus. w. soda

BORACITE (See p. 56)

Slowly vol.; small scales

sol. in H2O ; greasy feel

Sassolite ( Boric Acid) (See p. 29)

H3Bo3

Mn in borax bd.

Sussexite

Decrepitates, exfoliates; Ca reac. in dil. sol. w. am. oxalate

Colemanite

(See p. 34)

Mo reac. in s.ph. bd. or H2SO4; H2O in c.t.; on ch. fus. and MoO3 subl.

Molybdite (See p. 92)

Yel. powder or earthy mass ; greasy feel ; V in s.ph. bd. ; H2O in c.t. ; fus. easily to blk. non-mag, slag

CARNOTITE (See p. 135)

V2O5-nH2O

As subl. w. soda and ch. in c.t.

CaSO4 ppt. w. H2SO4 in cone. HC1 sol. Sectile; thin flakes flex.

Pharmacolite (See p. 49)

HCaAsO4-2H2O

'mag. after r.f.; not alk. after ign.; sol. in HC1 without res. or gel. sil.

Color.

Luster.

Hardness.

Specific Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fracture.

Wh., grn., yel., red, brn., blk.

Res. to

adamant

3J-4

Iso. tetr. ; gran., comp.

C. 6, dodec. per., 60°, 90°, 120° F. conch.

Bnh-blk. .

Resinous

8M

Hex. hemimor. ; fibr.

F. uneven, splintery

Grn., blue, violet, red, brn., cols.

Vitreous to greasy

Hex., us. prisms

C. 1, basal, poor to distinct F. uneven, conch.

Wh. to pale grn. or yel.

Vitreous to resinous

Mon.

F. uneven

Salmon-color, yel. to brn.

Vitreous to resinous

Orth. ; us. mass.

C. 2, basal, per. and pinac.

Deep red or redh-purple

Silky

Orth.(?); us. mass.

C. 2, pinac. 90° F. uneven

Lemon-yel. to S-yel.

Adamant. C. pearly

Orth.; tabular, pseudotetr.

C. 1, basal, per., flakes brittle

Cols., wh., gryh., bluish, .

Vitreous to resinous

i-U

Mon.; us. comp.

C. 1, pinac., per. F. conch.

Wh.

Silky

Mon.; fibrous

Very fragile

Cols., wh., yel., gry., grn.

Vitreous

Iso. tetrh.; us. isolated xls.

F. conch, 'uneven

Cols., wh., yel., gry.

Pearly

Tri.; small scales

C. 1, basal, per. greasy feel

Wh., yelh., pinkish

Silky

Orth.(?); fibr.

F. splint.

Cols., wh., yelh., gryh.

Vitreous to adamant.

Mon.; prism, xls.; gran.

C. 2, pinac., per., 90° F. uneven, conch.

Straw-yel. to wh.

Silky to adamant; C. pearly

Orth.; earthy, crusts

C. 1, basal

Canary-yel.

Dull

Hex.(?); us. earthy

Wh., gryh., redh.

Vitreous to pearly

2 -2£

Mon.; us. fibr. crusts, powder

C. 1, pinac., per. F. uneven

SECTION 18. Nomnctallie luster; f us. 1-5; no metal on ch.; not

Name.

Composition.

Fus. quietly to cols, glass

Whitens in c.t.; Na flame w. gypsum

Natrolite

(See p. 35)

2H20

Fus. with intumescence

To cols, glass; B-flame

DATOLITE (See p. 53)

To blebby glass; efferv. in HC1

CANCRINITE (See p. 91)

To wh. blebby enamel ; Na flame w. gypsum ; pyroelectric

THOMSONITE (See p. 53)

5H2O

To voluminous frothy slag; pyelectric

Scolecite (See p. 36)

3H2O

To wh. blebby enamel ; Na flame w. gypsum ; not pyroelectric

Mesolite

To white blebby enamel ; not pyelectric

LAUMONTITE (See p. 41)

2H2O

SECTION 19. Nonmetallic luster; fus. 1-5; no metal on ch.; not mag.

Efferv. of H2S in HC1

Na flame; BaSO4 ppt. w. BaCl2 in HC1 sol.

LAZURITE (Lapis Lazuli) (See p. 148)

ZnO subl. w. soda on Pt wire. (See p. 189)

Danalite

(R Mn. Fe, Zn)

A g C 1 p p t. w. AgNO3 in HNO3 sol.; Na flame

Fus. to cols, glass

SODALITE (See p. 124)

Fus. to opaq. . bd.; Zr reac. w. turmeric paper

Eudialyte (Eucolite)

(Some K, H, Fe, Mn: Ce, Cl)

Wh. BaSO4 ppt. w. BaCl8 in dil. HC1 sol.

Contains much Ca (Ppt. Si and Al first). See Silicon (2), p. 185

Hauynite (Hauyne)

Contains little or no Ca

Noselite (Nosean)

Mn in borax bd. Cp. willemite, below)

Wh. ZnO subl. in fine powder w. soda on Pt. wire; grn. w. (See p. 189)

TROOSTITE (See p. 90)

Little or no Zn; gel. in cold HC1

TEPHROITE (See p. 63)

Mn2SiO4 (Some Mg, Fe)

mag. after r.f.; not alk. after ign.; sol. in HC1 w. gel. sil.; water in c.t.

Color.

Luster.

Hardness.

Specific Gravity.

Fusibility.

Crystallization and Structure.

Cleavage arid Fracture.

Cols., wh., yelh., ., .

Vitreous to pearly

2.2-2. 3

Orth. ; prism., pseudotetrag, radial, fibr.

C. 2, prism., per., 89° F. uneven

Cols., ., yelh., .

Vitreous

5 -5J

2-2 . 5

Mon. ; us. xls. ; gran.

F. conch, to uneven

YeL, pink, ., bluish, gry., wh.

Vitreous to greasy

Hex.; us. comp.

C. 3, prism., GO0, 120° F. uneven

Cols., wh., grn., brn.,

gry.

Vitreous to pearly

Orth. ; us. radial, fibr.

C. 2, pinac., per., 90° F. uneven

Cols., or wh.

Vitreous or

silky

Mon.; us. slender radiated

C. 2, prism., 88J° F. splint., uneven

Cols., wh., gry-, ycl.

Vitreous to silky

Mon.; acic.

C. 2, prism., per.

Wh., yelh., gryh., redh.

Vitreous C. pearly

Mon.; prism., radial

C. 3, pinac. and prism., per., 96°, 94°, 137° F. uneven

after r.f. ; not alk. after ign. ; sol. in HC1 w. gel. sil. ; little or no water in c.t.

Deep azure to -blue

Vitreous

Iso.; comp.; xls., Fig. 7, dodec.

C. 6, dodec. 60°, 120°, poor F. uneven

Flesh-red to gry.

Vitreous to resinous

5H>

Iso. tetrh.; us. mass.

F. uneven

Wh., gry., blue grn., redh.

Vitreous to

greasy

3M

Iso.; comp., dissem.

C. 6, dodec., 60°, 90°, 120° F. conch., uneven

Rose, -red, brn.

Vitreous

Hex. rhom.

C. 1, basal, per. F. splint.

Blue, grn., red, yel., wh.

Vitreous

Iso.

C. 6, dodec. F. uneven

Gry., grn., blue, brn., blk.

Vitreous

5.}

3 §-4

Iso.

F. uneven

Apple-grn., flesh-red, brn.

Vitreous

4-4 £

Hex. rhom.; us. mass.

C "%

prism., 60°, 120° F. uneven

Smoky-gry., -red

Vitreous to greasy

5f-6

3-3 J

Orth.; us. C. 2, pinac., 90° gran., comp. IF. uneven, conch.

SECTION 19. — Concluded. Nonmetallic luster; f us. 1-5; no metal on ch.; not

Name.

Composition.

ZnO subl. w. soda on Pt wire (See p. 189)

May also contain Mn

(See p. 90)

Zn2SiO4 (Often Mn, Fe)

Contain Si, Al, and Ca. See Silicon (2), p. 185

Easily sol. in HC1; Na flame

Nephelite

( Elaeollte) (See p. 44)

Approx. NaAlSiO4 (Some K and Ca)

Dif. sol. in HC1; Na flame w. powdered gypsum; fus. to cols, glass

ANORTHITE (Lime Feldspar) (See p. 37)

(Some Na)

Fus. w. intumes. to dark slag

ALLANITB (Orthlte) (Seep. 71)

(Also La. Nd. Pr. Y. etc.)

Fus. w. slight intumes. to . or yelh. glass

Melilite

Ti w. H2O2

Gel. sil. in HC1

Schorlomite (See p. 102)

Not included above

Swells and cracks apart on ign.; often glows; str. gnh-gry.

Gadolinite (See p. 73)

SECTION 20. Nonmetallic luster; fus. 1-5; no metal on ch.; not mag. after

Micaceous; flex., but not elastic, or little so

Exfoliates greatly b.b. Hydrated mica

VEKMICULITB (Jefferlslte) (See p. 75)

Hydrous Mg-Fe-Al silicate (Somet. Na. K)

Dif. fus.; little or no Al or Ca; much Mg. See Silicon, (2) p. 185

Us. compact . mass.; sometimes fibrous (chrysotile, commercial "asbestos") or foliated (marmolite)

Serpentine

(Chrysotile: Marmolite) (See p. 122)

H4Mg3Si2O9

(Some Fe, somet. Nl)

Somewhat like a gum or resin

DEWEYLITE (Gymnlte) (See p. 50)

(Somet. Nl)

Compact, fine earthy texture; when dry floats on H2O

SEPIOLITE (Meerschaum) (See p. 49)

H4Mg2Si3Oio (Somet. Cu and Nl)

Whitens and fus. quietly

To clear glass ; Na flame

Analcite

(See p. 53)

To translucent glass; BainHCl

HARMOTOME (See p. 34)

4H2O

To blebby wh. enamel. ; K flame w. gypsum

Phillipsite (See p. 34)

5H2O

mag. after r.f.; not alk. after ign.; sol. in IIC1 w. gel. sil.; little or no water in c.t.

Color.

Luster.

Hardness.

Specific Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fracture.

Yel., red, grn., brn., wh., cols.

Vitreous

Hex. rhom.; comp., gran., dissem.

C. 3, basal and prism., 60°, 120° F. uneven, conch.

Cols., gry., ., redli., yelh.

Vitreous to greasy

Hex. hemimorph. ; comp., gran.

C. 3, prism., 60°, 120° F. uneven, conch.

Cols., wh., gry., redh.

Vitreous

C -G£

Tri., prism, xls., cleav., comp.

C. 2, basal., per. and pinac., 87° F. uneven

Brn. to blk.

Res., vitr. to submit.

5f-6

3 . 0-4 . 2

Mon.; us. mass.

F. uneven, conch.

Grn., yel., brn., wh.

Vitreous to resinous

Tetr.; us. xls.

C. 1, basal F. uneven

Blk.

Vitreous

Iso. ; comp.

F. conch.

. to -blk.

Vitreous to greasy

Mon.; comp., gran.

F. conch., splint.

r.f.; not alk. after ign.; decomposed by HC1 w. separation of sil.; water in c.t.

Yel., brn., It. to dk. grn.

Pearly

i-U

si

Mon.; fol., scaly, flaky

C. 1, basal, per. Thin flakes flex., not elastic

Olive to - grn., yelhgrn., wh.

Greasy, wax-like, silky

5-5 J

Mass.; pseudomorphous, fibrous

F. uneven, splint. Fibers tough

Yel., wh., ., redh.

Resinous

Amorph.

F. uneven, conch. Much cracked

Wh. to gryh-wh.

Dull

2 -2J

Compact; earthy

F. uneven, conch.

Cols., wh. yelh., redh.

Vitreous

Iso.; us. xls., Trapazoh., Fig. 3

F. uneven, conch.

Wh., gry., yel., red, brn.

Vitreous

Mon.; us. twinned or radiated tufts

C. 2, pinac., 90° F. uneven

Wh., redh.

Vitreous

Mon. ; twinned, or radiated tufts

C. 2, pinac., 90° F. uneven

234 SECTION 20.— Concluded. Nonmetallic luster; f us. 1-5; no metal on ch.; not mag.

Name.

Composition.

Fus. quietly

To wh. enamel; Na flame; little H2O. Gmelinite often cracks and splits b.b.

PECTOLITE (Seep. 52)

Gmelinite

6H2O

Fus. with intumes.

To b 1 e b b y white enamel

K flame

APOPHYLLITE (See p. 33)

(A little F)

Slowly and diff. sol. in HC1; little H2O

PREHNITE (See p. 125)

(Fe Iso. w. Al)

Gives slimy sil. inHCl

Chabazite

(See p. 42)

(Somet. K. Na, Ba, Sr)

To white enamel

Exfoliates b.b.

Stilbite

(Desmlne) (See p. 32)

Pearly cl. faces lozenge-shaped

HEULANDITE (See p. 32)

SECTION 21. Nonmetallic luster; fus. 1-5; no metal on ch.; not mag. after r.f.; not alk.

Yel. WO3 res. on boiling inHCl

Strong Mn reac. in borax bead

Huebnerite

(See p. 21)

(Fe Iso. w. Mn)

Ca w. am. oxalate; cuproscheelite, Cu flame

SCHE ELITE (Cuproscheellte) (See p. 89)

(Us. also Mo; somet. Cu)

Fus. quietly to glassy globule; slowly sol. in HC1

Us. striated on best cl. ; often brilliant play of color

Labradorite

(Ca-Na Feldspar) (See p. 37)

(n:m l:l to 1:3)

Fus. dif. to wh. globule; rather easily sol. in HC1

HC1 sol. gives no Al ppt. w. am.; but Ca reac. w. am. oxalate

Wollastonite

(See p. 35)

CaSiO3 (Somet. H, Mg)

Ti reac. w. H2O2

Fus. w. intumes. to dk. glass

Titanite

(Sphene) (See p. 82)

CaSiTiO5 (Some Fe; somet. Mn)

Fus. w. intumes. to white mass

Cl reac. w. AgNOs; slowly sol. in acids; Na flame

WERNERITE (Scapollte) (See p. 44)

n:m 3: 1 to 1:2)

after r.f . ; not alk. after ign. ; decomposed by HC1 w. separation of sil. ; water in c.t.

Color.

Luster.

Hardness.

Specific Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fracture.

Cols., wh., gry.

Vitr, silky. C. pearly

4H>

Mon.; fibr., radiated, comp.

C. 2, pinac., per., 85°, 95° F. splint., uneven

Wh., yel., flesh- red, .

Vitreous

2£

Hex. rhom.; us. xls.

C.3,prism.60°,1200 F. uneven

Wh., ., yelh., redh.

Vitreous; C. pearly

4£-5

H

Tetr.; us. cube-like xls.

C. 1, basal, per. F. uneven

Apple-grn., gry., wh.

Vitreous

Orth.; us. globular; tabular xls.

C. 1, basal, poor F. uneven

Wh., yel., flesh-red

Vitreous

Hex. rhom.; xls. nearly cubic

C. 3, rhom., 85° F. uneven

Wh., yel., brn., red

Vitreous; C. pearly

2-2 £

Mon.; twinned; sheaf-like radiated

C. 1, pinac. per. F. uneven

Wh., yel., gry., red, brn.

Vitreous; C. pearly

Mon.; tabular xls. look orth.

C. 1, pinac. per. F. uneven

after ign. ; decomposed by HC1 w. separation of sil. or yel. WO3 res. ; little or no water in c.t.

Brn. to - blk.

Resinous

Mon., us. xls.

C. 1, pinac. per. F. uneven

Wh., yel., grn., brn., redh.

Vitreous to adamant

Tetr. ; gran. ; xls. like octahedrons.

C. 4, pyram., 49°, 80° F. uneven, conch.

Wh., gry., brn., grn.

Vitreous to pearly

Tri. ; us. mass.

C. 2, basal, per. and pinac., 86° F. uneven

Cols., wh., gry., yel., red, brn.

Vitreous ; C. pearly

Mon.; us. gran., fibr., comp.

C. 2, pinac., per., 84 £° F. uneven

Gry., brn., yel., grn.

Res. to

adamant

5 -5£

Mon.; tabular wedge-shaped xls.

C. 2, prism.,66r F. conch. P. 4, pyram.

Wh., gry., ., bluish, redh.

Vitreous to pearly

Tetr.; comp., gran., stout prisms

C. 3, prism, and pinac., poor F. uneven, conch.

SECTION 23. Nonmetallic luster; f us. 1-5; no metal on ch.; not mag.

Name.

Composition.

Li flame; thin flakes elastic

Easily fus. to wh. or gry. globule; acid H2O in c.t. on intense ign.

Lepidoljte

(Llthla Mica) (See p. 31)

Exfoliates greatly; fus. w. dif . ; much H2O in c.t.

Cookeite

Decomposed by boiling cone. H2SO4. (Flakes lose luster and transp. and acid becomes turbid) ; thin flakes elastic, except chlorite and kammererite

Us. dk. col.; often w. quartz and feldspar and in igneous rocks

Biotite

(Black Mica) (See p. 58)

(A little F, often TO

Gel. silica w.HCl

Lepidomelane

Lt. to dk. col.; much more readily decomposed than biotite

Phlogopite

(Magnesia Mica) (See p. 106)

(Some F, Fe)

Thin flakes flex, but not elastic; much H2O

Chlorite

(Cllnochlore, etc.) (See p. 104)

H,Fe,Mg,Al silicates

Rose-red; Cr in borax bd.; thin flakes flex, but not elastic

Kammererite (Chrome Chlorite) (See p. 75)

Si30i3

Not decomposed by boiling cone. H2SO4. (Flakes retain luster and transp., acid remans clear)

Common It. colored mica; elastic; us. w. quartz and feldspar

Muscovite

(Potash Mica) (See p. 30)

(Often some Na, Ca, Mg, Fe, F)

Na flame ; thin flakes elastic

Paragonite (Soda Mica) (See p. 31)

Soft; greasy feel; thin flakes flex, but not elastic ; sectile

Talc

(Steatite, Soapstone) (See p. 29)

H2CaAl4Si2Oi2 (Some Fe, Na, K)

Thin flakes brittle; harder than true micas

Margarite

(Brittle Mica) (See p. 32)

Fus. easily to blk glass; V in s. ph. bead

ROSCOELITE (Vanadium Mica) (See p. 105)

(Some Mg, Fe)

after r.f.; not alk. after ign.; insol. in HC1; micaceous, foliated, or scaly

Color.

Luster.

Hardness.

Specific Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fracture.

Lilac., gryh-wh., redh., yelh.

Pearly

2-2J

Mon.; us. scaly, comp.

C. 1, basal, per. Flakes tough, elastic

Wh. to yelhgrn.

Pearly

Mon.; us. scaly

C. 1, basal, per. Flakes elastic

Grn., yel., brn., blk.

Splendent to pearly and submit.

Mon.; 6-sided plates, scaly

C. 1, basal, per. Flakes tough, elastic

Blk. to -blk.

Adamant, to pearly

Mon.

C. 1. basal, per. Flakes tough

Yelh-brn., grn., wh., cols.

Pearly to submit.

Mon.; 6-sided xls., plates, scales

C. 1, basal, per. Flakes tough, elastic

Grn. of various shades

Vitreous to pearly

5-5 £

Mon.; scaly, foliated

C. 1, basal, per.

Rose-red to deep red

Vitreous to pearly

Mon.; scaly, foliated

C. 1, basal, per. Flakes tough, flex.

Wh., gryh., yelh., ., .

Vitreous to pearly

Mon.; foliated, flaky, scaly

C. 1, basal, per. Flakes tough, elastic

Yelh., ., gryh-wh.

Pearly to vitreous

2 . 8-2 . 9

Mon.; us. scaly, comp.

C. 1, basal,, per. Flakes tough, elastic

Apple-grn., gry., wh.

Greasy ; C. pearly

(Somet. 3 -4)

Mon.; us. foliated, gran., comp.

C. 1, basal, per. Sectile Flakes flex. F. uneven

Pink, gry., wh., yelh.

Vitreous; C. pearly

Smi

Mon., scaly, micaceous

C. 1, basal, per. Flakes brittle

Dk. grn. to brn.

Pearly

Mon.(?) minute scales

C. 1, basal, per.

SECTION 23. Nonmetallic luster; f us. 1-5; no metal on ch.; not mag.

Name.

Composition.

FELDSPAR Group. — G. 2.5-2.8. 2 cl. at 90° or nearly so; It. col. Fus. quietly; H. near

K flame, w. gypsum

Microcline may show striations on cl. or xl. faces ; adularia transp. or opalescent; sanidine glassy

Orthoclase

(Potash Feldspar; adularia; sanidlne)

(See p. 37)

KAlSi3Os (Na Iso. w. K) (Sanidlne contains Na)

MICROCLINE (See p. 37)

(Na Iso. w. K)

Strong Na flame w. gypsum ; little or noK

Us. fine striations on best cleavage; these Plagioclase Feldspars form a continuous series from albite to ariorthite. Labradorite and bytownite slightly sol in HC1; anorthite slowly sol. giving gel. sil. Distinguished by sp.gr.

Albite

(Soda Feldspar) (See p. 37)

NaAlSi3O8 (Us. some Ca; often K)

Oligoclase

(Na-Ca Feldspar) (See p. 37)

(m:n 6:l to 3: 1)

Andesine

(Na-Ca Feldspar) (See p. 37)

(w:n 3:'l to 1:1)

Labradorite

(Ca-Na Feldspar) (See p. 37)

m:n= 1: 1 to 1:3

Bytownite

(Ca-Na Feldspar) (See p. 37)

(m:n=l:3tol:6)

Anorthite

(Lime Feldspar) (See p. 37)

CaAl2Si2O8 (Us. some Na)

AMPHIBOLE Group.— G. 2.9-3.4. Prism and cl. angles 56° and 124°. Xls. us prismatic, often divergent or radialcolumnar. Separate xls. us. 6-sided, vertically striated, and terminated by 2 planes. Fus. quietly or w. little intumes.

Fus. to dark shiny globule ; us. intumes. slightly and gives Na flame

Hornblende

(See p. 61)

(Also Al, Na; often H. F)

Fus. to . or . globule; but little Na flame; sometimes asbestiform (fibrous)

Actinolite

(Nephrite or Jade In part)

(See p. 110)

(Somet. Fe)

(Somet. also Al)

(SiO3):

Fus. to cols, or nearly cols, glass; sometimes asbestiform (fibrous)

Tremolite

(Asbestos In part; (Nephrite or Jade In part)

(See p. 36)

Dif. fus. (5-6); sometimes asbestiform (fibrous)

Anthophyllite (Asbestos In part) (See p. 62)

Strong Na flame ; fus. easily

Glaucophane (See p. 112)

after r.f.; not alk. after ign.; insol. in HC1; distinct cleav., 2 directions

Color.

Luster.

Hardness.

Specific Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fracture.

Cols., wh., cream, fleshred, gry.,

Mon.; Figs. 24-44

C. 2, basal, per. and pinac. 90°

grn.

6-6?

2.54-2.57

Tri.

C. 2, basal, per. and pinac. 89° 30'

2.62-2.64

Tri.; Fig. 46

C. 2, basal, per. and pinac. 86° 24'

Vitreous

2.65-2.67

3M

Tri.; us. comp.

C. 2, basal, per. and pinac. 86° 32'

gry., ., bluish, redh. Often a beau-

to pearly

2.68-2.69

Tri.; us. comp.

C. 2, basal, per. and pinac. 86° 14'

colors on (010), most notable in

2.70-2.72

Tri.; us. comp.

C. 2, basal, per. and pinac. 86° 4'

2.73-2.75

Tri.; us. comp.

C. 2, basal, per. and pinac.

85° 58'

2 . 75-2 . 76

Tri.

C. 2, basal, per. and pinac.

Grn. to blk.

Vitreous to pearly

Mon.; us. prism, xls.; gran.

C. 2, prisnx per., 56° F. uneven, splint.

Grn. of various shades

Vitreous to pearly

Mon.; slender prism., radiating

C. 2, prism, per., 56° F. uneven, splint Fibers flex.

Wh., gry.

Vitreous to pearly

Mon., bladed, fibr., comp.

C. 2, prism, per., 56° F. uneven Fibers flex.

Gry., clove-brn., grn.

Vitreous to pearly

Orth.; us. fibr. or lamellar

C. 2, prism, per., 54i° F. splint. Fibers flex.

Lavender-blue to azure-blue; gryh., and bluish-blk.

Vitreous to pearly

6-6 £

Mon.; us. columnar or fibr.

C. 2, prism, per., 58° F. uneven, conch. Fibers flex.

SECTION 23.— Concluded. Nonmetallic luster; fus. 1-5; no metal on ch.

PYROXENE Group. — G. 3.0-3.7. Prism and cleav. angles 87° and 93°; cleav. not very pronounced. Xls. us. nearly square prism w. truncated edges 4- or 8-sided. Basal parting often distinct. Fus. quietly or w. little intumes.

Dif. fus. (6); luster often metalloidal (Cp. hypersthene)

Fus. to cols, or nearly cols. glass

Fus. to . or . col. deepens w. increase of Fe. Diallage is lamellar to fibrous w. pearly to metalloidal luster

Fus. to shiny blk. glass; often Na flame; contains Al and ferric Fe

Fus. to blk. globule, somewhat mag.; strong Na flame

Fus. readily to transp. blebby glass; Na flame. Us. in very tough compact mass

Swells and fus. to clear or wh. glass; Li flame (may be obscured by Na)

Mn in soda bead; fus. to nearly blk. glass

Mn in soda; Zn w. soda on Pt. wire. (See p. 189)

Name.

Enstatite

(Bronzlte) (See p. 36)

Diopside

(See p. 36)

Pyroxene

(Diallage) (See p. Ill)

Hedenbergite (See p. Ill)

AUGITE (See p. 62)

Aegirite (Acmite) (See p. 63)

JADEITE (Jade In part) (See p. 54)

SPODUMENE (Hldenlte; Kunzlte) (See p. 38)

Rhodonite

(See p. 83)

Fowlerite (See p. 83)

Jeffersonite

(Also Al, somet. Mn Na)

Zn-Mn-Pyroxene

SECTION 24. Nonmetallic luster; fus. 1-5; no metal on ch;

Gel. w. HC1 after fus. ; iso. xls.; red color

SPESSARTITE (Mn Garnet) (See p. 102)

(Us. also Fe and Ca)

Do not gel. after fus.; I 2 cl. nearly 90°

Fus. to nearly blk. glass

Rhodonite

(See p. 83)

MnSiO3 (Fe, Ca Iso. w. Mn)

(Fe, Ca.Mg Iso. w. Mn)

(Ca,Mn)(Mg,Fe,Zn) (SiO.-Oa

Wh. ZnO subl. w. soda on Pt. wire (slight); grn. w.

Fowlerite (Zn Rhodonite) (See p. 83)

Jeffersonite (Mn-Zn Pyroxene)

not mag. after r.f.; not alk. after ign.; insol. in HC1; distinct clcav., 2 directions

Color.

Luster.

Hardness.

Specific Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fra.cture.

Yelh., gry., brn., grn.

Pearly to bronzy

Orth.; us. lamellar

C. 2, prism., 88°, poor F. uneven

Cols., wh., pale grn.

Vitreous

3 .2-3.6

Mon.; us. xls., Figs. 40, 41

C. 2,, prism, 87°, poor F. uneven

Lt. to dk. grn.

Vitreous

Mon.; us. xls., Figs. 40, 41

C. 2, prism, 87°, poor F. uneven

-blk. to blk.

Vitreous

Mon.

C.2,prism,87°,poor F. uneven

-blk to blk.

Vitreous

Mon., gran., columnar

C. 2, prism, 87°, poor F. uneven

. to -blk.

Vitreous

6 -6£

Mon.; prism.

C. 2, prism., 87°, poor F. uneven

Wh., gryh., .

Vitreous C. pearly

Mon.; comp.

F. splint., tough

Wh., gry., pink, emeraldgrn., purple

Vitreous pearly

Mon.; cleavable, comp.

C.2,prism,per.,87° F. uneven, splint.

Rose-red, pink, brn.

Vitreous

2J-3

Tri.; us. gran., comp.

C. 2, prism., per.,

87§° F. uneven, conch.

(See below)

(See below)

mag. after r.f.; not alk. after ign.; insol. in HC1; Mn reac. in soda bead

-red to hyacinth-red

Vitreous

61-7*

Iso.; us. xls.

F. uneven, conch.

Rose-red pink, brn.

Vitreous

2H*

Tri.; us. gran., comp.

C. 2, prism, per., 87£° F. uneven, conch.

Rose-red

Vitreous

2 £-3

Tri.; gran., comp.

C. 2, prism, per.,

87£° F. uneven, conch.

-blk to brn.

Vitreous

Mon.; xls., gran., comp.

C. 2, prism., 87° F. uneven

SECTION 24.— Concluded. Nonmetallic luster; fus. 1-5; no metal on ch;

Name.

Composition.

Fus. w. much intumes. to blk. glass

Piedmontite (Mn Epldote)

Cb. reac. after fus. w. borax; samarskite gives U reac. in s.ph. bd.

Columbite

(See p. 134)

(Also Ta, and some Sn and W)

Samarskite (See p. 133)

W reac. after fus. w. soda

W. little soda on ch. becomes mag.

Wolframite

(See p. 21)

Little or no Fe

Huebneeitb

(See p. 21)

(Some Fe)

SECTION 25. Nonmetallic luster; fus. 1-5; no metal on ch.; not

Li flame; may beyelh-red or obscured by Na

Swells and fus. to clear or wh. glass. Hiddenite (emeraldgreen) and kunzite (lilac) are transp.

SPODUMENE (Hiddenite; Kunzite)

(See p. 38)

(Na Iso. w. LI)

Blue phosphorescence with gentle heat. Fus. to wh. enamel

Petalite

(Na Iso. w. LI)

P reac. after fus. w. soda Fus. easily w. intumes. to wh. globule

AMBLYGONITE (See p. 37)

(Nalso.>.Ll: OHw.F)

B flame (Cp. axinite, below)

Rdh. phosphorescence on heating; fus. to cols, glass

DANBURITE (See p. 102)

Fus. w. intumes. to wh. globule; Cl reac. w. CuO on ch.

Bobacite

(See p. 56)

Mg7Cl2Bi6O3o

(Mn, Fe, Mg Iso. w. Ca)

B flame w. KHSO4 and fluorite

Fus. w. intumes. and pale B flame

AXINITE (See p. 80)

Fus. w. intumes. to blebby glass or slag. Pyroelectric, especially lighter colored varieties. Achroite cols.; indicolite blue; rubellite red

Tourmaline

(Schorl; Achroite; Indlollte; Rubellite)

(See p. 74)

(R Mg, Fe,Ca,Na,K, LI; of ten some

not mag. after r.f.; not alk. after ign.; insol. in HC1; Mn reac. in soda bead.

Color.

Luster.

Hardness.

Specific Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fracture.

Redh-brn to redh-blk.

Vitreous

Mon. ; comp.

C. 1, basal, per. F. uneven

Fe-blk. to gry. and -blk.

Res. to submit.

Orth.; short prism, xls.

C. lr pinac., poor F. uneven, conch.

Velvet-blk.

Vitreous to res.

4J-5

Orth.; us. mass.

F. conch.

Dk. gryh-blk. to . blk.

Res. to submit.

5 -5*

Mon.; us. xls., gran.

C. 1, pinac. per. F. uneven

Brn. to bnh-blk.

Resinous

Mon.; us. xls.

C. 1, pinac. per. F. uneven

mag. after r.f.; not alk. after ign.; insol. in HC1; not previously included

Wh., gry., pink, emeraldgrn., purple

Vitreous to pearly

Mon.; cleavable, comp.

C. 1, prism, per., 87° F. uneven, splint. P. 1, pinac.

Wh., gry., pink, .

Vitreous; C. pearly

Mon.; us. mass.

C. 1, basal, per. F. uneven '

Wh. to pale grn., or blue

Vitreous to greasy; C. pearly

Tri.; us. mass.

C. 1, basal, per. F. uneven

Wh. to pale yel., yelh-brn. and cols.

Vitreous

7 -7*

Orth.; us. xls. like topaz

F. uneven, conch.

Cols., wh., gry., yel., grn.

Vitreous

Iso. tetrh.; us. isolated xls.

F. conch., uneven

Clove-brn., gry., grn., yel., blk.

Vitreous

2-2 £

Tri. xls., Fig. 45 tabular

C. 1, pinac. F. conch.

Blk., brn., grn., blue, red, pink wh.

Vitreous to resinous

Us. .3

Hex. rhom. hemimor. ; Fig. 58; prism., curved triangular cross-section

F. conch., uneven

SECTION 25.— Continued. Nonmetallic luster; f us. 1-5; no metal on ch.;

Name.

Composition.

GARNET Group.— Fus. quietly (except uvarovite) and gel. w. HC1 after fus. Us. dodecahedrons and trapezohedrons. (Figs. 3, 7, 8). No cleavage; parting somet. distinct 6 directions, 60°, 90°, 120° (110)

Ca (grossularite) or Mg (pyrope) ppt. after fus. w. soda and separating Si and Al (See Silicon (2), p. 185)

GROSSULARITE (Ca-Al Garnet) (See p. 102)

(Often Fe. Mg, Mn)

Pyrope

(Mg-Al Garnet) (See p. 101)

(Often Fe, Ca. Cr)

Fus. to mag. globule

ALMANDITE (Fe-Al Garnet) (See p. 101)

(Mn, Mg, Ca Iso. w. Fe)

Mn in borax bd. (strong)

SPESSARTITE (Mn Garnet) (See p. 102)

(Fe, Ca Iso. w. Mn; Fe Iso. w. Al)

Partially sol. in HC1 w. gel. sil.

ANDRADITE (Ca-Fe Garnet) (See p. 102)

(Fe, Mn, Mg Iso. w. Ca; Al Iso. w. Fe)

Cr in s.ph. bd. ; fus. w. dif.

Uvarovite (Ca-Cr Garnet) (See p. 102)

(Al Iso. w. Cr.)

Fus. easily to wh. transl. glass

Wh. ppt. BaSO4 in HC1 sol.; much H2O in c.t. at low temp.

HARMOTOME (See p. 34)

Fus. easily to cols, blebby glass

Sol. w. gel. after ign.; H2O in c.t.; very hard

Lawsonite (See p. 38)

Fus. dif. and quietly

Whitens and fus. to vedic. scoria; varieties with Na, Li, Cs, more fus.

BERYL (Emerald, deep green; Aquamarine, pale)

(See p. 127)

(Some H; somet. Na, LI, Cs. Ca)

A little H2O on intense ign. of powder in c.t.

CORDIERITE (lollte) (See p. 108)

Fus. to wh. enamel w. orange-yel. phosphoescence

Acid H2O in c.t.; P reac. w. am. mol. after fus. w. soda

Herderite

Fus w. intumes.

(Concluded on next page)

To . or . glass; gel. w. HC1 after fus.

Vesuvianite

(Idocrase) (See p. 101)

(Mg. Fe. Mn Iso. w. Ca)

To wh. blebby glass; strong Na flame; AgCl ppt. w. AgNOs in dil. HNO3 sol. after fus. w. soda

Wernerite

(Scapollte) (See p. 44)

(n : m 3 : 1 to 1 : 2)

To wh. blebby glass; gel. w. HC1 after fus. H2O in c.t.

PREHNITE (See p. 125)

(Fe Iso. w. Al)

not mag. after r.f.; not alk. after ign.; insol. in IIC1; not previously included

Color.

Luster.

Hardness.

Specific Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fracture.

Pale red, yel., grn., wh.

Vitreous

tt-n

Iso.; us. xls., Figs. 3, 7, 8

F. uneven to conch.

Deep red to redh-blk., rarely purple

Vitreous

6J-7J

Iso.; us. xls., Figs. 3, 7, 8

F. uneven to conch.

Deep red to -blk.

Vitreous

Iso.; us. xls., Figs. 3, 7, 8

F. uneven, conch.

-red to hyacinth-red

Vitreous

6I-7J

Iso.; us. xls., Figs. 3, 7, 8

F. uneven to conch.

Wine-red, ., yel., brn. to blk.

Vitreous to resinous

Iso.; us. xls., Figs. 3, 7, 8

F. uneven to conch.

Emerald-grn.

Vitreous

Iso.; us. xls., Figs. 3, 7, 8

F. conch.

Wh., gry., yel., red, brn.

Vitreous

Mon.; us. twinned, radiating

C: 2, pinac., 90° F. uneven

Pale blue to gryh-blue

Vitreous to greasy

7*-8

Orth. ; us. xls.

C. 2, basal and pinac., per., 90°

Grn., blue, yel., pink, cols.

Vitreous to resinous

Hex.; us. prism, xls., Fig. 49

C. indistinct F. conch touneven

Blue to violet and cols.

Vitreous

. 7 -71

5-5 £

Orth.; pseudohex. xls., gran.

C. 1, pinac. F. conch., uneven P. 1, basal

Wh. to pale grn. or yel.

Vitreous

Mon.

F. uneven

Grn., brn., yel.

Vitreous to resinous

Tetr. Figs. 27, 28; gran.

F. uneven

Wh., gry., grrih., bluish, redh.

Vitreous to pearly

Tetr.; stout prism., comp., gran.

C. 3, prism, and pinac., poor F. uneven, conch.

Apple-grn., gry., wh.

Vitreous

Orth.; us. reniform

F. uneven

SECTION 25.— Concluded. Nonmetallic luster; fus. 1-5; no metal on

Name.

Composition.

Fus. w. intumes. — Concluded

To a slag which gel. w. HC1; a little H2O on intense ign. in c.t.

Lt. col. slag

Zoisite

(See p. 33)

Brn. or blk. slag; us. mag.

Epidote

(Plstaclte) (See p. 79)

Fus. w. slight intumes. to colored glass

Ti reac. w. H2O2

Titanite

(Sphene) (See p. 82)

CaSiTiO6 (Some Fe; somet. Mn)

Benitoite

Exfoliates and fus. w. dif. Greasy feel

Pink col. after ign. w. us. gives H2O in c.t. on intense ign.

Talc

(Steatite, Soapstone) (See p. 29)

SECTION 26. Nonmetallic luster;

CARBO- NATES.— CO2 efferv. in dil. HC1.

(Cp. also the carbonates on the next page, particularly r h o- do chrosite and siderite, which may contain some Ca and give alkaline reaction after ignition.)

(Concluded on next page)

Sr flame; swells and throws out fine branches on intense ign.

Wh. ppt. SrSO4 w. dil. H2SO4 in dil. HC1 sol.

Strontianite

(See p. 34)

(Somet. Ca Iso. w. Sr)

Ba flame on intense ign.

Wh. ppt. BaSO4 w. dil. H2SO4 in dil. HC1 sol.

Barytocalcite

Ca flame w. HC1; dil. H2SO4 gives w h . p p t . CaSO4 i n cone. HC1 sol. but n o t i n very dil. sol., showing presence of Ca and absence of Sr and Ba (Abundant ppt. w. am. oxalate. See P. 177)

Lumps efferv. freely in cold dil. HC1. Aragonite powder colored lavender on boiling in sol.; decrepitates b.b.

Calcite

(CalcSpar: Marble Limestone; Chalk.)

(See p. 40)

CaC03 (Mg. Fe, Mn, Pb Iso. w. Ca)

CaCO3 (Sr, Pb Iso. w. Ca)

(Fe, Mn Iso. w. Mg)

(Mn Iso. w. Mg)

CaCO3-CaSiO3- CaSO4-15H2O

Aragonite

(See p. 41)

Lumps efferv. freely in hot but not in cold dil. HC1; sol. reac. for Mg after ppt. of Ca

Dolomite

(Pearl Spar) (See p. 40)

Becomes blk. and slightly mag. on ign.

Ankerite (Fe Dolomite) (See p. 40)

Much H2O in c.t.; wh. BaSO4 ppt. w. BaCl2 in dil. HC1 sol.

Thaumasite

ch.; not mag. after r.f.; not alk. after ign.; insol. in HC1; not previously included.

Color.

Luster.

Hard- . ness.

Specific Gravity.

Fusibility.

Crystallization and Structure.

Cleavage and Fracture.

Gryh-wh., grn., pink, yelh-brn.

Vitreous; C. pearly

6 -6£

Orth.; columnar, bladed

C. 1, pinac. per. F. uneven

Yelh. to - grn., gry.

Vitreous

Mon.; us. prism.

C. 1, basal, per. F. uneven

Gry., brn., yel., grn.

Resinous to adamant.

5 -5£

3 .4-3.6

Mon.; us. tabular, wedgeshape xls.

C. 2, prism, F. uneven P. 4, pyram.

Sapphire-blue, It. blue, cols.

Hex.; us. prism.

Apple-grn., gry., wh.

Greasy; C. pearly

1 -2* (somet. 3 -4)

Mon.; us. foliated, comp., gran.

C. 1, basal, per. F. uneven; sec tile, thin flakes flex.

fus. above 5; alk. after ign.

Wh., gry., yel., grn.

Vitreous

3J-4

Orth.; us. columnar; xls. pseudohex.

C. 2, prism., 63° F. uneven

Wh., gry., yel., grn.

Vitreous

Mon.; us. prism.

C. 2, prism, per. F. uneven

Cols., wh., and variously tinted

Vitreous

Hex. rhom.; Figs. 52-57

C. 3, rhom. per., 75° F. conch., seldom observable

Cols., wh., and variously tinted

Vitreous

Orth.; often pseudohex.

C. 3, pinac., poor F. uneven

Cols., wh., and variously tinted

Vitreous to pearly

3*-4

Hex. rhom.; gran., corp.; xl. faces curved

C. 3, rhom. per., 74° F. conch., uneven

Brn., gry., redh., seldom wh.

Vitreous to pearly

Hex. rhom.

C. 3, rhom. per., 74°

Wh., cols.

Vitreous to dull

Hex.; fibr. or mass.

F. splint., uneven

SECTION 20.— Concluded. Nonmetallic

Name.

Composition.

Carbonates — Concluded

Contains Mg — Little or no ppt. w. am. oxalate i n HC1 sol., but much w. Na phosphate. Alkaline reac. w. turmeric paper may be weak

Scarcely affected by colddil.HCl. Wh. fragments become pale pink on ign. w. Co (NO 3) 2. Breunnerite gives much ppt. w. am. after boiling HC1 sol. w. a drop of HNO3, Hydromagnesite gives much H2O in c.t.

Magnesite

(See p. 42)

MgC03

(Somet. Fe, Mn)

Breunnerite (Fe Magneslte; Brown Spar)

(See p. 42)

(Mn Iso. w. Mg)

Hydromagnesite

3H2O

Sol. quietly in warm HC1

Glows on ign.; becomes pale pink if previously moistened w. Co (NO 3) 2

BKUCITE (See p. 30)

(Fe, Mn Iso. w. Mg)

Sulphates. — Acid H2O in c.t. and SO odor after intense ign.

Al reac. w.

Readily sol. in H2O

Kalinite (Potash Alum)

Slowly attacked by HC1 ; decrepitates b.b.

ALUNITB (See p. 52)

(Na Iso. w. K)

SECTION 27. Nonmetallic luster; fus. above 5; not

CARBO- NATES CO2 e

fferv. [Cl.

Mn in borax bd. ; decrepitates b.b.

Sometimes enough Fe to make mag. on ch.

Rhodochrosite

(Dlaloglte) (See p. 88)

(Ca, Fe, Mg, Zn !so. w.

Mn) j

Ni in borax bd.

H2O in c.t.

Zaratite (See p. 147)

Wh. ZnO subl. w. soda on Pt wire ; grn. subl. w.

(See p. 189)

Little or no H2O in c.t.

Smithsonite

(Dry-bone Ore) (See p. 43)

(Often Fe, Mn; somet. Ca, Mg)

H2O in c.t. ; Cu flame w. HC1

Aurichalcite

H2O in c.t.; no Cu

Hydrozincite (See p. 49)

(Mn Iso. w. Mg)

FeC03 (Ca, Mg. Mn Iso. w. Fe)

MgCO3 (Somet. Fe, Mn)

3H20

Becomes blk. and mag. on ign.; much ferrous Fe

HC1 sol. reac. for both Mg and Fe. (See breunnerite, Sec. 26, above)

Breunnerite (Fe Magneslte) (See p. 42)

Decrep. inc. t. ; little or no Mg or Ca

Siderite

(Spathic Iron) (See p. 41)

Mg re.ic. in HC1. sol. after removing Fe and Ca. (See Magnesium (3), p. 182)

Little or no H2O in c.t.

MAGNESITE (See p. 42)

Much H2O in c.t.

Hydromagnesite

luster; fus. above 5; alk. after in.

Color.

Luster.

Hardness.

Specific Gravity.

Crystallization and Structure.

Cleavage and Fracture.

Wh., yel., gry., brn.

Vitreous, silky, dull

3 Ml

Hex. rhom.; us. comp., gran.

C. 3, rhom. per., 72° F. conch.

Yelh., .,- gry. Seldom wh.

Vitreous

3Mi

Hex. rhom.

C. 3, rhom. per.72|°

Wh.

Vitreous to silky

Mon. ; us. acic.

Wh., gry., grn., blue

Waxy, vitr. C. pearly

2£

Hex. rhom.; us. foliated

C. 1, basal, per. Sectile; flakes flex.

Cols., wh.

Vitreous

Iso. pyr.; us. fibr.

C. conch.

Wh., gry., redh.

Vitreous

3J-4

Hex. rhom.

C. 1, basal, poor F. uneven

alk. after ign. ; sol. in HC1 without res. or gel. sil.

Rose-red, dk. red, brn.

Vitreous to pearly

3Mi

Hex. rhom.; gran., comp.

C. 3, rhom. per., 73° F. uneven

Emerald-grn.

Vitreous

Compact, incrust.

F. smooth

Brn., grn., blue, pink, wh.

Vitreous

Hex. rhom.; us. botry., incrust., cellular

C. 3, rhom. per., 72° F. uneven, splint.

Pale grn. to blue

Pearly

Mon.; us. acic., gran., laminated

F. splint.

Wh., gry., yel.

Dull

Earthy, compact, fibr.

F. uneven, splint.

Yelh. ., gry. Seldom wh.

Vitreous

Hex. rhom.

C. 3, rhom. per., 72 £° F. conch.

Gry. and brn. of different shades

Vitreous to pearly

Hex. rhom.; gran., comp.

C. 3, rhom. per., 73° F. uneven

Wh., yel., gry., brn.

Vitreous, silky, dull

3Mi

Hex. rhom.; gran., comp.

C. 3, rhom. per., 72|° F. conch.

White

Vitreous to silky

Mon.; us. acic., bladed, chalky

F. splint., uneven

SECTION 27.— Continued. Nonmotallic luster; fua.

Name.

Composition.

SULPHIDES. — H2S efferv. inhotHCl

Wh. ZnO subl. after intense ign. w. soda on Pt wire; subl. grn w. (See p. 189)

Sphalerite

(Zinc Blende) (See p. 88)

ZnS (Fe, Mn, Cd Iso. w. Zn)

Wurttite (See p. 130)

ZnS (Some Fe)

Red-brn. CdO subl. after intense ign. w. soda on ch.

GREENOCKITE (See p. 140)

CdS

SULPHATES. — Wh. p p t. BaSO4 w. BaCl2 i n HC1 sol.

Al reac. w. on ch.

Readily sol. in H2O; K flame

Kalinite (Potash Alum)

Sol. in H2O; no flame react; alum taste

Alunogen

Readily sol. in H2O; wh. ZnO subl. w. soda on Pt wire after intense ign.; taste astringent, metallic, nauseous

Goslarite

ZnSO4-7H2O

(Fe Iso. w. Zn)

Blackens and becomes strongly mag. b.b.; fus. 5-6 in fine splinters; slowly sol. in HC1 to yel. sol. which reacts for ferric Fe

St. -red

Little or no H2O in c.t.

Hematite

(See p. 134)

Fe2O3 (Somet. Tl, Mg)

H2O in c.t.; us. decrepitates

TURGITE (Hydrohematlte) (See p. 144)

FeO-OH, Fe2O3,H2O

St. yelh-brn. H2O in c.t.

Us. prismatic xls. Lepidocrocite scaly

GOETHITE (Lepidocrocite) (See p. 142)

FeO-OH

Amorphous, mammillary, botryoidal, stalactitic

Limonite

(Brown Hematite; Bog Iron Ore)

(See p. 131)

FeO-OH-nH2O (Often clay, sand, etc.)

Mn in borax bd.

Wh. ZnO subl. w. soda on Pt wire after intense ign.; subl. grn. w. (See p. 189)

Zincite

(Red Zinc Ore) (See p. 141)

ZnO

(Mn Iso. w. Zn)

Earthy, powdery, frothy; H2Oinc.t.

Wad

(Bog Manganese) (See p. 17)

MnO,MnO2,H2O

(Often Fe, SI, Al, Ba)

MnMn2O4

:

Co.Mn oxides (Often Fe, SI. Al)

Little or no H2O in c.t.

Hausmannite (See p. 131)

Co in borax bd.

Mn in soda bd. ; H2O in c.t.

Asbolite (Earthy Cobalt)

P reac. w. am. mol.

(Concluded on next page)

Cu flame

TURQUOIS (See p. 124)

(Some Cu)

Wh. CaSO4 ppt. w. H2SO4 in cold cone. HC1 sol. F reac. w. H2SO4

APATITE (See p. 98)

(Cl ISO. W. F)

above 5; not alk. after ign.; sol. in HC1 without res. or gel. sil.

Color.

Luster.

Hardness.

Specific Gravity.

Crystallization and Structure.

Cleavage and Fracture.

Wh., grn., yel., red, bra., blk.

Resinous to adamant.

Iso. tetr.; gran., comp.

C. 6, dodec. per., 60°, 90°, 120° F. conch.

Bnh-blk.

Resinous

3J-4

Hex. hemimor.; us. fibr.

F. uneven, splint.

Honey-, citron-, or orange-yel.

Resinous to adamant.

Hex. hemimor.; us. incrust.

C. 3, prism., 60°, poor F. conch.

Cols., white

Vitreous

2 -2£

Iso. pyr.; us. fibr.

F. conch.

Wh., yelh., redh.

Vitreous to silky

1J-2

Mon.; us. fibr., incrust.

F. splint.

Wh., yelh., redh.

Vitreous

2 -2J

Orth. ; us. comp.

C. 1, pinac. per.

Red to redh-blk.

Dull to submit.

Mass.; earthy Hex. rhom.

F. uneven splint.

Red to redh-blk.

Dull to submit.

Botry- crusts, stalac., earthy

F. uneven, splint, earthy

Yel. or redh-brn. to blk.

Dull to adamant.

Orth.; acic. or scaly

C. 1, pinac. per. F. splint., uneven

Yel., brn. to . blk.

Dull, silky

5 -5J

Mass., fibr., bo try., earthy

F. splint., uneven,

Deep red to orange-yel. St. yel.

Adamant.

4 -4J

Hex. hemimor.; us. gran., lamellar

C. 1, basal, per. F. uneven

Bluish or - blk. to dull blk.

Dull

Earthy, amorph., comp.

F. earthy

Bnh-blk. St. chestnutbrn.

Submetallic

Tetr.; pyr. xls.; gran.

C. 1, basal F. uneven

Blk., brn.

Dull

1 -2J

Mass.; earthy

F. uneven, earthy

Blue, bluishgrn., grn.

Waxy

Tri.; incrust., comp.

F. conch.

Grn., blue, violet, brn., yelh., cols.

Vitreous to sabres.

Hex., us. prisms; gran.

C. 1, basal, poor, to distinct F. uneven, conch.

SECTION 27.— Concluded. Nonmetallic luster; fus. above

Name.

Composition.

P reac.

— Concluded.

Al reac. w. on ch.

WAVELLITE (See p. 122)

(Some F Iso. w. OH)

Much Mg; no Ca. See Magnesium (3), p. 182. Sectile

Brilliant glow on intense ign.; Mg reac. w. on ch. if mineral is light colored.

BRUCITE (See p. 30)

(Fe. Mn Iso. w. Mg)

SECTION 28. Nonmetallic luster; fus. above

Wh. ZnO subl. w. soda on Pt wire. G r n. subl. w.

(See p. 189)

Decrep. and gives H2O in c.t.; pyroelectric ; almost infus. (fus. 6)

Calamine

(Hemlmorphlte; Smlthsonite)

(See p. 35)

Little or no H2O A little H2S on sol. in c.t. in HC1

Danalite

(R Mn, Fe, Zn)

No H2S on sol. in HC1 (Cp. troostite, p. 230)

WILLEMITE (See p. 90)

Zn2SiO4 (Mn, Fe Iso. w. Zn)

Cu globule w. soda on ch.

H2O in c.t.

(See p. 148)

H2CuSiO4

Fein borax bd.; little or no H2O in c.t. (Cp. next 2 minerals, which often contain a little Fe)

Much Mg but no Al or Ca in HC1 sol. (See Magnesium (3), p. 182)

Olivine

(Chrysolite, Peridot) (See p. 85)

(Somet. a little Nl, Sn, Tl)

Swells and cracks apart on ign. ; often glows; str. gnh-gry.

Gadolinite (See p. 73)

Mg2SiO4 (Some Fe)

Little or no Fe

Much Mg; noAlnorCa

Forsterite (See p. 85)

F reac. w. KHS"O4; may react for Fe

A little H2O on intense ign. in c.t.

CHRONDEODITE (See p. 100)

(Some Fe)

Al2SiO5-5H2O

ThSiO4 (Some H2O, somet. U)

Al reac. w. on ch.

Much H2O in c.t. ; crumbles on ign.

ALLOPHANE (See p. 121)

Str. orange to dk. brn.

Brn. to -red on ign.

Thorite (Orangelte) (See p. 130)

5; not ;ilk. ;ift<-r ipi.; sol. in IK'l v,it!i!;ut res. or gel. sil.

Color.

Luster.

Hardness.

Specific Gravity.

Crystallization and Structure.

Cleavage and Fracture.

Wh., yel., grn., brn.

Vitreous to pearly

3-J-4

Orth.; us.

radiating

C. 3, pinac., 73°, 90° F. uneven, conch.

Wh., gry., , grn., blue

Waxy, vitreous; C. pearly

2 -2£

Hex. rhom.; us. foliated

C. 1, basal, per.; flakes and fibers flex.

5; not alk. after ign.; sol. in HC1 w. gel. sil.

Wh., pale-grn., blue

Vitreous

Orth. hemimor., cockscomb groups, tabular

C. 2, prism, per., 76° F. uneven, conch.

Flesh-red to

gry.

Vitreous to resinous

Iso. tetrh.; us. mass.

F. uneven

Yel., red,, grn., brn., wh., cols.

Vitreous

Hex. rhom.; comp., gran.

C. 3, prism., 60°, 120° F. uneven, conch.

Emerald-grn.

Vitreous

Hex. rhom.; us. prism.

C. 3, rhom. per., 54° F. conch., uneven

Olive-grn. to gryh-grn., brn.

Vitreous

Orth; Fig. 36; gran., dissem.

C. 2, pinac., 90°, F. conch., uneven

Blk., -blk., brn.

Vitreous to greasy

Mon.; comp., gran.

F. conch., splint.

Wh., yelh., gryh., gnh.

Vitreous

Orth.; us. xls.

C. 2, pinac., 90° F. uneven

-red., yel., wh.

Vitreous

6-6£

Mon.; comp., gran.

C. 1, basal F. uneven

Cois., yel., grn., blue

Vitreous to waxy

Amorph. ; us. crusts

F. conch., earthy

Blk., brn., orange

Resinous, greasy

4 §-5

Tetr. ; us. xls.

C. 2, prism., 90° F. conch.

SECTION 29. Nonmetallic luster; fus. above 5; not alk. after

Name.

Composition.

Yel. WO 3 powder in boiling HC1

Ca reac. w. am. oxalate in HC1 sol.

SCHEELITE (See p. 89)

(Us. some Mo, somet. Cu)

Darkens and gives H2O in c.t.

Cu globule w. soda on ch.

CHRYSOCOLLA (See p. 120)

CuSiO3-2H2O

Ni in borax bd.

GARNIERITE (Genthlte) (See p. 120)

H2O in c.t.; amorphous, fibrous, or foliated

Us. compact .; sometimes fibrous (chrysotile, commercial "asbestos") or foliated (marmolite)

Serpentine

(Chrysotile; Marmolite)

(See p. 122)

H4Mg3Si2O9 (Some Fe, somet. Nl)

Resembles a gum or resin

DEWEYLITE (Gymnlte) (See p. 50)

(Somet. Nl Iso. w. Mg)

H4Mg2Si3Oio (Somet. Cu and Nl Iso. w. Mg)

Compact; fine earthy texture; Mg reac. w. on ch. Fus. 5. Adheres to tongue

SEPIOLITE (Meerschaum) (See p. 49)

Al reac. w. on ch.

K flame w. powdered gypsum; us. trapezohedrons

Leucite

(See p. 54)

(Na Iso. w. K)

Clay-like; sometimes transl. or transp. in H2O

Halloysite (See p. 47)

H4Al2Si2O9-nH2O

SECTION 30. Nonmetallic luster; fus. above 5; not

Slowly attacked by hot HC1 w. evolution of H2S

Wh. ZnO subl. w. soda on Pt wire; grn. w.

(Seep. 189)

Sphalerite

(Zinc Blende) (See p. 88)

ZnS (Fe, Mn, Cd Iso. w. Zn)

ZnS (Some Fe)

H,Fe,Mg,Al silicates (Often a little Cr)

Si3Ol8

Wurtzite (See p. 130)

Become strongly mag. on ign.

Slowly and dif. sol. in HC1

Iron Ores

(See Sec. 12, p. 218)

Micaceous or foliated

(Concludec

Flakes tough and elastic

Fus. w. dif.

MICA (See Sec. 22, p. 236)

Flakes flexible but not elastic (Cp. talc, and pyrophyllite, next page)

on next page)

Much H2O in c.t. on intense ign.; varieties rich in Fe become black and mag. (prochlorite)

Chlorite

(Cllnochlore; Pennine; Prochlorlte)

(See p. 104)

Cr in borax bd.; mineral pink to rose-red

Kammererite (Chrome Chlorite) (See p. 75)

ign.; decomposed by HC1 w. separation of sil. or yel. WO3 powder

Color.

Luster.

Hardness.

Specific Gravity.

Crystallization and Structure.

Cleavage and Fracture.

Wh., yel., grn., brn., redh.

Vitreous to adamant.

5 . 9-6 . 1

Tetr.: xls. like oct., gran

C. 4, pyram., 49 1°, 80° F. uneven, conch.

Bluish-grn., -blue, brn., blk.

Vitreous, earthy

Amorph., comp.

F. conch, to uneven

Pale to deep grn., yelh.

Dull to resinous

Amorph., botry., comp.

F. uneven, conch.

Olive-grn., -grn., yelh-grn., wh.

Greasy, waxy, silky

Comp., fibr.

F. conch., splint. Fibers flex., tough

Yelh., wh., ., redh.

Resinous

Amorph., like gum or resin

F. uneven, conch., much cracked

Wh., to gryhwh.

Dull

Compact; earthy

F. uneven, conch.

Wh., gry., cols.

Vitreous

5J-6

Iso.; us. trapezo., Fig. 3

F. uneven, conch.

Wh., gry., ., yelh., bluish, redh.

Pearly, waxy, dull

Mass.; earthy

F. uneven

alk. after ign.; insol. in HC1; scratched w. knife

Wh., grn., yel., red, brn., blk.

Resinous to adamant

8M

Iso. tetrh.; gran., comp.

C. 6, dodec. per., 60°, 90°, 120° F. con~h.

Bnh-blk.

Resinous

3M

Hex. hemimor.; fibr.

F. uneven, splintery

t

Grn. of various shades

Vitreous to pearly

Mon.; scaly, foliated

C. I, basal, per. Thin flakes flex.

Rose-red to deep red

Vitreous to pearly

1 -2J

Mon.; scaly, foliated

C. 1, basal, per. Thin flakes flex.

SECTION 30. — Continued. Nonmetallic luster; fus. above 5;

Name.

Composition.

Micaceous — Concluded

Flakes brittle; H2O in c.t.

Whitens and fus. w. dif . on thin edges

MARGARITE (Brittle Mica) (See p. 32)

H2CaAl4Si2Oi2 (Some Fe, Na. K)

Greasy feel; very soft

A little H2O in c.t. on intense ign. (Cp. kaolinite and bauxite, below)

Al reac. w. on ch.; radiated variety exfoliates greatly b.b.

Pyrophyllite

(Agalmatollte) (See p. 29)

Mg reac. w. onch.; sectile

Talc

(Steatite; Soapstone) (See p. 29)

14H2O

(Often Th, Yt)

Yp04

(Er; somet. Ce and Th)

(F Iso. w. OH)

(Some Cu)

SiO2-nH2O

or Al2Si05

(Na Iso. w. K)

H4Al2Si209

Mixture A1O- OH and

(Often Fe, Si, Ca, Mg)

Much H2O readily given in c.t.

Like butter or cheese; brittle when dry; decomposed by £[2804

Saponile

P reac. w. am. mol. after fus. w. soda; us. pale blue-grn. flame

Monazite us. transp. or transl.; Xenotime is opaque

Monazite

(See p. 99)

XENOTIME (See p. 81)

Al reac. w. on ch.; us. radiated or globular

WAVELLITE (See p. 122)

Blue col.; b.b. swells, loses col. and crumbles

Lazulite (See p. 124)

Cu flame; in c.t. decrepitates, yields H2O, turns brn. or blk.

Turquois

(See p. 124)

Fus. to clear glass w. equal amt. of soda on Pt wire

H2O in c.t. at high temp.

Opal

(See p. 54)

Al reac. w. on ch.

Little or no H2O in c.t. H4-5 lengthwise; 6- 7 crosswise

CYANITE (Dlsthene) (See pp. 109, 113)

H20

in c.t.

Decrep. b.b. ; SO2 and acid H2O at high temp, in c.t.

ALUNITE (See p. 52)

Insol. sil. skeleton in s.ph.bd.; us. clay-like, compact, or mealy

Kaolinite

(Kaolin: Porcelain Clay) (See p. 47)

Wholly sol. in s.ph. bd. (Bauxite mark on glass with heavy pressure, adheres firmly)

BAUXITE (See p. 47)

GlBBSITE (Hydrargllllte) (See p. 50)

not alk. after ign.; insol. in HC1; scratched w. knife

Color.

Luster.

Hardness.

Specific Gravity.

Crystallization and Structure.

Cleavage and Fracture.

Pink, gry., wh., yelh.

Vitreous; C. pearly

Smj

Mon.; scaly, micac., gran.

C. 1, basal, per.; thin flakes brittle

Wh., apple-grn., gry., yel., brn.

Pearly to dull

Orth.; fol., fibr., radial

C. 1, basal, per.; thin flakes flexible F. uneven, splint.

Apple-grn., gry., wh.

Greasy ; C. pearly

Mon. us.; fol., comp.

C. 1, basal, per.; sectile F. uneven Flakes flexible

Wh., yelh., ., bluish, redh.