Economic Geology and the Bulletin of the Society of Economic Geologists 1924-12: Vol 19 Iss 8

1924 · Historical

Economic Geology and the Bulletin of the Society of Economic Geologists 1924-12: Volume 19 , Issue 8. Digitized from IA1518511-02 . Previous issue:…

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Economic Geology

VoL. XIX. DECEMBER, 1924. No. 8

The Pegmatites.’*

James Furman Kemp.

In the present-day development of views on the origin of many ore-deposits, pegmatites have come to occupy a place of increas- ing significance. We may almost consider them the cardinal pivot on which our arguments turn. They have not been alto- gether overlooked in the past, as will be seen by any reader who with this point in mind goes over the text-books and papers of general and comprehensive character which began to appear in the early nineties with the rejuvenation of mining geology. As attention has been more and more drawn, however, to the con- nection between the processes set up by expiring igneous activity, especially when developed by intrusive masses, the pegmatites have acquired additional significance. Doubtless they have been overlooked in their true theoretical relations by many students of mining geology in the past because, among the common metals, tin is almost the sole one of out-standing importance which is characteristically found in them. Only in quite recent years have tungsten and molybdenum come into the foreground as constituents of special steels. The pegmatites as the home of feldspar and quartz for porcelains; of mica for its various uses, and of the rarer oxides, lithia, glucina, zirconia, thoria and the other members of the cerium group of elements, have not espe- cially appealed to those observers and students whose attention

1 Presidential Address before the Society of Economic Geologists, New York Meeting, May, 1924.

698 Sames Furman Kemp.

was concentrated on copper, lead, zinc, the precious metals and even iron.

Yet in the very dawn of mining, in the remote prehistoric times, pegmatites as the source of tin for bronze must have caught the eye of some acute observer whose placers and gossans began to fail in their yield. It is not a coincidence without an underlying cause that we find the earliest writers of the significant papers about the pegmatites drawing their illustrations from Cornwall and Saxony, the ancient sources of tin and the an- cestral homes respectively of English-speaking and German- speaking miners. While the mining geologists may have ne- glected their study somewhat, the geologists who were busied with rocks and especially igneous rocks and their relations—the petrologists of an earlier day—were not unmindful of them, nor of their variations toward the siliceous extreme of the quartz vein; nor of the related more diffused reactions which led to wide impregnation of rocks with tourmaline and topaz as well as feldspar, quartz, and mica.”

2In the preparation of this address, the writer has been especially aided by the following papers in addition to the early ones subsequently cited in the text. The subject has also been one of personal observation and study since student days in the early eighties.

1890. W. C. Broegger, “ Die Mineralien der Syenitpegmatitgange der Siid- norwegischen Augit- und Nephelinsyenite.” Zeitsch Kryst., 16: especially 215- 235, 1890. A translation by N. N. Evans of the part relating to the origin of pegmatites appears in the Canadian Record of Science, 6: 33-46, 61-71, 1894. The term “ pneumatolitic ” was used by Broegger in 1890.

1894. W. O. Crosby, “The Origin of the Coarsely Crystalline Vein-Granite or Pegmatite,” Am. Geol., 13: 215-216, 1894. The paper is a condensation of one read before the Geological Society of America, Dec. 27-29, 1893, but not printed in the Society’s Bulletin. It was the forerunner of the completer elabo- ration by W. O. Crosby and M. L. Fuller, “ Origin of Pegmatite,” Technology Quarterly, 9: 326-356, Dec., 1896; Am. Geol., 19: 147-180, 1897, but the theo- retical views are quite well set forth in the earlier citation. Professor Crosby introduced the term “ aqueo-igneous ” which is very significant. We find it also in W. O. Crosby, “A Classification of Economic Geological Deposits, Based on Origin and Original Structure,” Am. Geol., 13: 249-268, 1894. Tech. Quart., 7: 27-48, 1894. Three grand divisions are established: A, Deposits of igneous origin; B, Deposits of aqueo-igneous origin (giant granite or pegmatite) ; C, De- posits of aqueous origin.

eres

The Pegmatites. 699

The name pegmatite is generally believed to have been given by the Abbé Haiiy in 1822 to the peculiar intergrowth of quartz

1894. J. H. L. Vogt, “ Ueber die durch pneumatolytische Processe an Granit gebundenen Mineral-Neubildungen,” Zeitschr. fiir prak. Geol., 2: 458, Dec., 1894. This paper is an elaboration of an earlier one in Norwegian: “Om dannelse af jernmalmforekomster ” (On the Formation of Iron Ore-deposits), 1892.

1895. George H. Williams, “ Origin of the Maryland Pegmatites,” 15th Ann. Rep. U. S. Geol. Sur., 675-684, 1895.

1896. C. R. Van Hise. The origin of pegmatites is discussed in the “ Princi- ples of North American Precambrian Geology,” 16th Ann. Rep. U. S. Geol. Sur., Part I., 686-688. On p. 687 is the following: “ Under sufficient pressure and at a high temperature there are all gradations between heated waters containing mineral material in solution and a magma containing water in solution. In other words under proper conditions water and liquid rock are miscible in all propor- tions.”

1899. J. F. Kemp, “ Granites of Southern Rhode Island and Connecticut,” etc Bull. Geol. Soc. Amer., 10: 372-375, 1899. Transitions from normal pegmatite to quartz veins with a few feldspars, and to pure quartz veins, are noted.

1904 and 1906. J. E. Spurr, “ Development of the Theory of Metalliferous Veins of Magmatic Quartz,” Chapter IV. of Professional Paper 55, U. S. Geol. Survey, pp. 129-156, 1906. A valuable review of the literature on this phase of pegmatites and of localities. Earlier, in Bull. 225, U. S. Geol. Sur., pp. 113-114, 1904, the same general conception of the veins is briefly outlined.

1908. John B. Hastings, “ Origin of Pegmatite,’ Trans. Amer. Inst. Min. Eng., 39: 104-128, 1908.

1909. QO. Stutzer, “ Ueber Pegmatite und Erzinjectionen,” etc., Zeitsch. fiir prak. Geol., 17: 130-135, March, 1909.

In recent years many papers have also appeared upon the pegmatites of Mada- gascar by Alfred Lacroix and other French writers. The richness of these dikes in rare minerals, many of gem grade, is their special claim to interest.

In Waldemar Lindgren’s invaluable treatise on “ Mineral Deposits,” the chapter on Pegmatites is of great importance and full of suggestions.

3 The custom prevails in the textbooks on rocks, which one ordinarily con- sults, such as Zirkel’s, Rosenbusch’s, and Holmes’ Nomenclature of Petrology, to simply refer to “ Hatiy, 1822,” for the first use of the name pegmatite. F. H. Hatch in his “ Textbook of Petrology,” London 1910, cites Haiiy’s “ Traité de Mineralogie,” 1822, p. 536. There were two editions of this famous work, one in 1801, which is generally in the libraries, but makes no mention of pegmatites; and a later one in 1822 not so generally accessible. The full reference is “ Traité de Mineralogie,” IV., 536, Paris 1822; “ Pegmatite(**), Feldspath laminaire avec cristaux de quartz enclavés. Schrift-granit, W. Vulgairement granite graphique. Composans accidentals, Mica, Tourmaline, Feldspath nacré dit pierre de lune. Appendice, Kaolin, Porcellanerde, W. Feldspath decomposé, provenant ordinairement du pegmatite.” W. stands for Werner.

De wijyua c’est-a-dire renfermant des piéces qui sont comme fichées dans une matiére principale.”

700 James Furman Kemp.

and orthoclase, or microcline, which had been previously called graphic granite and various other names based upon the re- semblance of the cross sections of the quartz to hebraic letters. The word pegmatite is derived from the Greek and means “ bound or cemented together in a framework,” the reference being to the quartz crystals which were held in the matrix of the feldspar. The significance of the word experienced modifications in the next thirty years, so that, especially among the French, it was applied to the veins or dikes of coarsely crystallized granite wherein these peculiar intergrowths were found. The next citation usually given for pegmatite is a paper by Delesse in 1849. When translated, he says:

The rock which I intend to describe forms very irregular veins which, without having a constant direction, cut all the granitoid rocks of the Vosges; the minerals which make it up are quartz, orthoclase, silvery mica, and most often also tourmaline. They are always nicely crystal- lized, and they even possess ordinarily a very coarse crystalline granitoid structure which is characteristic of pegmatite and which favors this type of deposit... .

The quartz is white, opaque and affords nothing of particular interest: it is in coarse crystals, a condition which generally holds good for the pegmatite; but in the Vosges its crystals are not oriented, although this relation is found in the variety of this rock which the geologists more especially include under the name graphic granite.

By the kindness of Professors F. D. Adams and R. Graham of McGill Univer- sity I have learned that Robert Jameson, in his “ Manual of Mineralogy,” Edin- burgh 1821, p. 348, in speaking of the crystallization of the constituent parts of granite refers to graphic granite as follows: ‘‘ This variety has been denominated Graphic Stone and is the Pegmatite of some geologists.” I have also found that in Cleveland’s “ Mineralogy,” Boston 1822, II., 732, under graphic granite a foot- note states: “‘ Pegmatite, Hatiy, Brogniart.” Using the suggestion of the name Brogniart as a clue and with the help of Miss A. P. Hepburn of the Columbia University Library, the following additional and older reference has been found:

“Essai d’une Classification Minéralogique des Roches Mélangées, par A. Brog- niart. Journal des Mines, tome 34, 1813, p. 32, in which is the following: “Espéce Pegmatite (Hatiy) Granite graphite, etc. Composée essentiellement de felspath lamellaire et de quartz. Observ. Tous les beaux kaolins dérivent de cette roche.” Thus Haiiy must have given the name before 1813 in some refer- ence not yet run down.

4Delesse, “Sur la constitution mineralogique et chimique des roches des Vosges; Sur la pegmatite avec tourmalines de Saint-Etienne (Vosges),” Annales des Mines, (4) XVI., 97-110, 1849.

The Pegmatites. 701

From the description by Delesse in 1849, we see that the name pegmatite since Hai coined it before 1822 had become expanded so as to mean a mass of rock in which the original graphic granite, or strictly speaking pegmatite, characteristically appeared, but even graphic granite was no longer necessary to it.

Reference is also frequently made to the standard textbook of C. F. Naumann, published in 1850. In Naumann’s “ Geog- nosie,” vol. I., page 574, under the varieties of granite, we find the following definitions.

Aplite or pegmatite; by these names the granites are described which consist almost entirely of orthoclase and quartz; one also means such granites as have been earlier included under the word halfgranite, in which for the most part only two essential components appear. .

Schriftgranit, 7.e., graphic granite (pegmatite in part); this remark- able aggregate of feldspar and quartz never appears in very large masses as an individual rock, but it forms only subordinate portions well within certain granites or gneisses; hence G. Rose has declared himself against the view that graphic granite should be regarded as a particular species of rock. As is well known, graphic granite consists of large feldspar in- dividuals, each of which encloses a number of prismatic quartz-individ- uals which are bounded by contact surfaces. The contact surfaces are usually striated and rarely show also evidences of corrosion. The pris- matic quartz crystals are all intergrown in the feldspar mass in parallel position according to a sharply defined law. On the cleavage faces of the feldspar the quartz-individuals appear with the cross sections which remind one of hebraic letters in their form and their arrangement in rows.

From these definitions it is evident that, in addition to the graphic granite of the Abbé Haity, Naumann included under the name pegmatite what later writers in English have called aplite or binary granite, practically the Alaskite of J. E. Spurr. In the second volume of his work, under what we would call strati- graphic geology, Naumann takes up under two heads the oldest rocks, 1.e., the ones which we today call the Precambrian. First he discusses the primitive formations; and second the granitic, eruptive ones. Under the last named, he describes on pages 195— 197 the different varieties of granite. One of these is pegma- tite. After referring to his definition of pegmatite in the first

- 702 James Furman Kemp.

volume, which I have cited above, he gives on page 196 the fol- lowing paragraph showing that, after all, he had in mind the same meaning for pegmatite which we understand today.

“ With the outstanding occurrences of pegmatite, belong also the beryl-bearing, extremely coarsely crystalline granite of Lan- genbielau in Silesia which forms dikes in gneisses. Quite similar are the dikes and stocks of granite which appear in the gneisses and mica schists of the Bavarian Mts. near Zwiesel; on Harlach Mt. near Maisried; and on the Hiinerkobel not far from Raben- stein.” A more detailed description of these three cases follows which shows them to be exactly what we mean by the coarsely crystalline granitic dikes or veins customarily named pegmatite today.

In 1853 Delesse discussed the pegmatites found in the north- eastern portions of Ireland.° This peculiar pegmatite was well supplied with cavities, having thus the structure later described as miarolitic. Into the cavities beautifully terminated crystals projected. On page 570, in discussing these phenomena, the author states: “It is then probable that the cavities are the re- sults of the action of gases; their forms and their character in- dicate, moreover, that the gases were set free at the moment when the rock was sufficiently consolidated to preserve the cavi- ties, but when it was still so plastic that the minerals could de- velop very freely.” We would conclude from this description that the author regarded the pegmatites as essentially igneous rocks, richly charged, however, with gases.

It would be tedious and ill advised to make too many citations from the earlier writers regarding the granite veins, as they were generally called among the English-speaking geologists. I will only refer to the writings of Edward Hitchcock, the pioneer State Geologist of Massachusetts and the first of the state ge- ologists who brought to completion an important report. In his famous volume on the geology of the State, published in 1833, he gives in his discussion of granite, from page 465 to 515, a

5“ Sur la Pegmatite de I’Irelande” in the Bull. Soc. Geol. de France, (2) 10: 568, 1853.

The Pegmatites. 703

great number of sketches of what he calls “veins of granite.” They are obviously the rocks which we would call pegmatites to- day because of the graphic granite which they contain and which is figured by Dr. Hitchcock and because of the associated min- erals which he frequently describes. The term vein is con- sistently applied to them. One would naturally infer that he meant by this, deposits from solution, but that is far from his intention. In the last paragraph on page 477, after giving many sketches of the so-called veins and irregular intrusive masses of the granite, he says: “I feel the inadequacy of such sketches to convey a just idea of the very great confusion which this spot exhibits. But if anyone can examine such places and still main- tain that granite was not forced up through the slate while in a fused state, I can only say that his mind must view facts in a very different light from my own.” Again after describing the occurrences with forty-eight different illustrations, he sums up five different arguments to prove the igneous origin of the granite in the so-called veins. We can scarcely avoid the im- pression that he had essentially the conception of dike veins. These illustrations of the views prevailing nearly a hundred years ago will perhaps suffice.

It is certainly true that at least a hundred years ago geologists were aware that in the pegmatites were concentrated many rare elements. As soon as the minerals had been systematically named and described and their compositions had been determined, the mineralogists and geologists of the day realized that the source of many of the species which contain the rare elements was evi- dently in the pegmatites. No good observer of field relations could, therefore, avoid realizing these associations; yet as re- marked above the pegmatites were regarded by mining engi- neers and geologists, and quite justly so, as being notably barren of useful metallic ores.

As we have come to realize, however, in the last thirty or thirty-five years and with greater and greater force the strong and important influence exerted by igneous phenomena in the production of our ore deposits, the pegmatites have acquired

704. James Furman Kemp.

much more prominent theoretical and scientific importance. They serve as a sort of connecting link between the igneous pro- cesses and those which we ordinarily associate with vein forma- tion.

One of the most important features which must be considered in reasoning about them is the enormous size of the individual crystals which appear in them. No conception of their method of origin will be defensible which does not satisfactorily estab- lish conditions favorable to these gigantic individuals. The largest of which I have discovered records or have any knowl- edge are the spodumene crystals in the pegmatites of the Harney Peak region, Black Hills of South Dakota. They were early de- scribed by W. P. Blake in the “ Mineral Resources” for 1884, page 608, and one unbroken crystal 36 feet long is mentioned; but they have also been reviewed at some length by Victor Ziegler in Bulletin 10 from the State School of Mines of South Dakota, in 1914. The largest crystal of which we have record was 42 feet long. A number have been exposed between 30 and 40 feet which were three to four feet in diameter. One, indeed is mentioned five feet four inches in diameter. They stand or lie like huge timbers in the midst of feldspar and quartz. Ziegler assumes a single crystal 35 feet long and three feet in diameter. He estimates that it will weigh 50,300 pounds or over 25 tons. We have three analyses of spodumene from these pegmatites giv- ing percentages of lithia, 1.18, 3.56, and 6.16. The first named would involve 593.5 pounds of lithia; the second 1790.7; and the last 3,098.5. In considering the process whereby pegmatites with these enormous crystals could form, we must also provide for the concentration in amounts something like the number of pounds given of such a rare oxide as lithia. Obviously, extreme mobility of molecules or ions must have existed, if, from an ordinary magma, this rare element is to be localized in such great quantities.

It should be remarked, however, that the Etta pegmatite knob or boss which contained the huge crystals projected 250 feet above the surrounding micaceous sandstone (W. P. Blake as

The Pegmatites.

cited, pages 603 and 606). In cross-section it is pear-shaped and roughly 230 by 280 feet. A small reproduction of a larg¢~ map made by Gilbert E. Bailey (“ Min. Res.,” 1884, p. 606).%

many banded pegmatites. The outer band up to 10 feet thick consisted of biotite and muscovite. The next band 40 to 100 feet thick contained the huge spodumenes in quartz and shading into an irregular inner band of greisen, containing cassiterite. As generalized on the map this inner band, specially rich in greisen and cassiterite, was 10-30 feet across. The innermost core which is eccentric in the mass consisted of quartz and feld- spar and was roughly 100 feet by 75 feet. If we picture to our- selves an intrusive stock of about the above dimensions forced from below into a resting place obviously beneath a thick cover- ing load of metamorphic rocks and itself a differentiate of some deeper seated granitic magma, we can see that it further differ- entiated as above. Assuming a homogeneous mass at the start, the components of biotite and to a less degree of muscovite, tended to the border. The spodumene became segregated in the next zone with quartz and toward the center with increasing pockets and masses of muscovite, quartz and cassiterite, or, col- lectively, “ greisen.” Finally in the portion last of all to chill and crystallize at the center, quartz and feldspar were the chief components. If we omit the unusual spodumene and cassiterite, very similar banded relationships may be observed in many rel- atively narrow dikes of which mention will be made farther on.

Other pegmatites in the Black Hills give crystals of great size for several other species, but none approach the gigantic dimen- sions of the spodumene. Tourmaline is recorded one foot in diameter ; garnets, up to seven and one quarter inches; masses of microcline five by six feet on the cleavage face; so-called “ books ” or crystals of muscovite two feet in diameter.

Passing to the pegmatites of New Hampshire, one recalls at ) once the great beryl crystals. J. D. Dana in his Treatise on : Mineralogy mentions one thirty-two inches by twenty-two inches

and four feet three inches long. Another crystal, according to

shows it to have a marked concentric structure, analogous to\ +

706 James Furman Kemp.

O. P. Hubbard, was forty-five inches long by twenty-four inches in diameter. Professor Hubbard estimated that it weighed 1,076 pounds per running foot in length, making in all nearly 2 1/2 tons. Crosby and Fuller state that the largest known of these beryls is in the Museum of the Boston Society of Natural His- tory, but do not give its exact dimensions. One would infer from the context that it was a yard in diameter (Tech. Quar., 9: 333). All the important mineral collections of the country have others not so large but very impressive in size.

Beryllium, or glucinum, is one of our rarer elements, so that conditions must be provided for its assemblage in these enormous amounts. Theoretically, the mineral contains 14.1 per cent. of beryllium oxide or glucina.

Among the feldspars, microcline sometimes grows to enor- mous size. In addition to the one mentioned above from the Black Hills, we may recall several others. Brush and Dana record in their studies of the extraordinary lithium and man- ganese minerals at Branchville, Connecticut, a single continuous cleavage face of microcline ten feet long.° Crosby and Fuller mention feldspars ten feet and more in length as frequent in the New Hampshire pegmatites. One crystal in the American Mine at Groton was measured by them at 20 feet. They recall Brog- ger’s observations described in the Canadian Record of Science, 6: 67, footnote (Zeitsch. Kryst., 16: 231). Brogger states: “In the granitic pegmatite dikes near Kure, south of Moss, I have seen individual feldspars more than 10 meters in length.”

Quartz crystals sometimes project into the vugs or miarolitic cavities and attain huge dimensions. In the Natural History Museum in Berne, Switzerland, I recall a group seen in student days abroad, whose individuals were each comparable to the thigh ofalargeman. J. D. Dana cites in the Treatise on Mineralogy, one from Waterbury, Vt., 2 feet long and 18 inches in diameter. Crosby and Fuller mention a vug at the Palermo Mine in Groton, N. H., which afforded a well-formed crystal about a yard in diameter (p. 336).

6 Amer. Jour. Sci., 20: 274, 1880.

The Pegmatites. 707

Mica crystals five and six inches in diameter are not uncommon. I have seen an aggregate of large biotite plates in Roe’s Spar “Bed” in the southwestern part of Crown Point, eastern Adirondacks, as large as a barrel. J. D. Dana in the “ Treatise on Mineralogy,” records crystals from Siberian pegmatites a yard in diameter. Great freedom of growth and lack of inter- ference must be assumed for these huge crystallizations of so soft and easily bent a mineral.

Some of the rarer minerals reach relatively large dimensions. From the pegmatites cut at Mineville in the eastern Adirondacks in the Sanford Bed, now called Old Bed Mine, W. P. Blake in 1858 described crystals of allanite, 8 to 10 inches long by 6 or 8 inches broad and one half inch thick. One crystal was secured by James Hall from this locality which was afterward given to the mineral collections of Yale, and was described by E. S. Dana.* In later years a pegmatite dike was cut in the working of the Smith Mine about a mile north of Old Bed, and from the dump, a rich supply of allanites have been collected by myself and others. The crystals perhaps reaching 5 or 6 inches in length as a maximum and half an inch in thickness form a sort of angular cellular aggregate with a filling of quartz and red ortho- clase or microcline. Hundreds of pounds of the material rich in allanite have been taken from the dump. Once when mentioning this occurrence to Professor Brogger while on an excursion in 1910 with him in the Christiania Fjord and visiting some of his

7W. P. Blake, “ Lanthanite and Allanite in Essex Co., N. Y.,” Amer. Jour. Sci., Sept., 1858, p. 245.

8 E. S. Dana, “ On a Crystal of Allanite from Port Henry, N. Y., Amer. Jour. Sci., June, 1884, p. 279. Port Henry is the large town on Lake Champlain, the shipping port of the Mineville ore which lies six miles back in the mountains The crystal came from Mineville. Many additional details of the local mineral- ogy will be found in Bulletin 138, N. Y. State Museum, “ Geology of the Eliza- bethtown and Port Henry Quadrangles,” by J. F. Kemp and R. Ruedemann, 1910, pp. 152-165. Dr. Ruedemann described the paleozoic strata. The writer has searched the Old Bed locality for the large allanites several times but only small ones could be found. The crystals from the Smith Mine are not greatly inferior and were entrusted to H. Ries, who has described and figured them in Trans. N. Y. Acad. Sciences, 16: 329-330, 1808.

708 James Furman Kemp.

most interesting pegmatites along with Whitman Cross, George Otis Smith and Joh. Konigsberger, he told us of a crystal of this rare mineral weighing, as I recall, about 75 pounds which he had carefully collected. While a deckhand was wheeling it in a truck over the gangplank to a small coasting steamer or launch, the man stumbled, and the crystal went overboard to the pro- found depths of the fjord—where it still reposes.

Instances could be multiplied of the huge crystals of the spe- cies mentioned and of others, such as tourmaline, but those al- ready cited will suffice. They show that no conception of the process or processes whereby pegmatites have formed can be de- fended unless it admits conditions of great mobility of the mole- cules or ions, so that not only the normal and abundant constitu- ents of the magma or solution, such as silica, alumina, potash and soda, can assemble in vast quantities and crystallize to gigantic crystals ; but that also the rare components such as lithia, glucina, the oxides of the cerium group, boron and fluorine can be drawn from what must have been a wide source of supply to centers of crystallization of impressive concentration. Whether this proc- ess is one of convection or of diffusion in a standing magma and of ionic transfer may be difficult to decide. Our one safe ground is great mobility of movement and consequently a high degree of fluidity in the conveying medium.

The interrelations of the minerals present also a subject dis- cussed by many of the writers who have written of the pegma- tites. Crosby and Fuller remark that in the mass of the rock as distinguished from the cavities, the order of crystallization is similar to normal granites, thus, from earliest to latest, “ tour- maline (and other basic species), biotite, muscovite, basic feld- spar, acid feldspar, and quartz.” This order coincides with the writer’s observations. Quartz certainly, is the last of all, and in many dikes forms the central part where it seems to be the last residue and to run along the central part like a residual filling. In the vugs, however, there is some reversal of the order—feld- spar preceding mica. In the latter half of the nineties the writer studied the granites along the northern shore of Long Island

: (

nd nd ee

ter

The Pegmatites. 709

Sound from Narragansett Bay to New Haven and was aided by G. van Ingen and W. D. Matthew in the preparation of the paper cited below. We found some interesting monazite crystals which were always included in biotite, having obviously preceded the biotite and become involved in its substance.°

The banded structure shown by pegmatites has been remarked by several early writers and has been referred to above. That muscovite plates grow out perpendicularly to the walls has been often observed. An excellent case can be seen on 110th St., New York, in the ledge beneath the southeast corner of the site of the Cathedral of St. John the Divine.*° Crosby and Fuller record the finer grain of crystallization which often marks the edges of pegmatite dikes next the wallrocks in the New Hampshire ex- posures and remark the analogy in this respect with true dikes. But it is the writer’s experience that we never see as finely fel- sitic textures as in the dikes from relatively dry igneous fusion, but rather textures of fairly coarse granitoid plutonics, which look finely crystalline only in comparison with the excessively coarse central portions. One of the chief characteristics of the pegmatites is this extremely coarse grain which is shown by dikes but a few inches across, and it is this character which forces us to explain the pegmatites by the abnormal presence of abundant vapors or mineralizers.

The intergrowth of quartz and feldspar, especially microcline, in graphic granite is one of the features noted more than a cen- tury ago, but it was only in fairly recent years and with the help of metallographic investigations that we have reached the concep- tion of the eutectic in explaining it. On any other basis this peculiar intergrowth is a hard thing to understand. By eutectic we mean the result of the simultaneous crystallization of two

9 J. F. Kemp, “ Granites of Southern Rhode Island and Connecticut,” etc., Bull. Geol. Soc. of Amer., 10: 374, 1899. W. D. Matthew, “ Monazite and Orthoclase from South Lyme, Conn.,” Sch. of Mines Quarterly, Apr., 1895, p. 231. The microcline of these pegmatites is often twinned on the Manebacher law—giving the mineral some crystallographic interest.

10 The banding was noted in 1884 by the writer, then a student under J. S. Newberry and described in a graduation thesis, published four years later in the Trans. N. Y. Acad. Science, 7: 55-56, 1888.

710 James Furman Kemp.

members of a binary series because they reach a state of mutual saturation and must, therefore, crystallize together. Quartz and orthoclase (or microcline) reach this stage when the proportions are approximately 25 per cent. quartz and 75 per cent. ortho- clase. The containing orthoclase is a single individual and the separate quartz blades belong to one individual or at least are of uniform crystallographic and optical orientation. Eutectics in pegmatites are not limited to quartz and feldspar. Tourmaline and quartz may display the same relationship.

The perthitic intergrowth of two kinds of feldspar suggests the same method of crystallization. An extraordinary case of what is probably also a eutectic is afforded by the tourmaline crystals which have been found in earlier years at Roe’s Spar Bed in Crown Point, N. Y. The tourmaline crystals up to an inch and more in diameter exhibit outer crystal form and even rhombohedral terminal faces quite comparable to the usual crys- tals, but except at the termination the tourmaline substance is at times not much thicker than a heavy coat of paint and the inside is feldspar. These tourmalines were first collected in 1875, and described by Professor E. H. Williams from a pile of feldspar on the dock at Port Henry.** Later in the systematic mapping of Crown Point township, I collected a number of crystals at the quarry. The eutectic conception of later years affords the most reasonable explanation of this, an otherwise difficult, problem.

Metallic or distinctly metalliferous minerals are not espe- cially abundant components of the usual pegmatites. Cassiterite, wolframite, molybdenite and pitchblende, the last three from their association with the former, have been long known. Mag- netite is prominent in the pegmatite dikes which cut the great magnetic iron ore-bodies at Mineville in the eastern Adirondacks and has been known to the writer for over thirty years, and to others much longer. A very careful and thorough review of the recorded instances of metals in pegmatites is given by J. E.

11 E. H. Williams, “ On Crystals of Tourmaline with Enveloped Orthoclase,”

Amer. Jour. Sci., Apr., 1876, pp. 273-275. The crystals are also figured in E. S.

Dana’s “ Textbook of Mineralogy,” p. 109, 1894, 17th edition.

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The Pegmatites. 7Ii

Spurr in the Professional Paper 55 of the U. S. Geological Sur- vey, in 1906, pp. 138. The metalliferous minerals embrace in addition to those mentioned, columbite, tantalite, zincblende, galena, pyrite, arsenopyrite, chalcopyrite, bornite, stibnite, sper- rylite and native gold. In the closely related quartz veins, re- viewed in their world-wide distribution on pp. 142-156, a num- ber of others were added. It is quite evident, therefore, that in instances minerals, such as magnetite and pyrite, have been rather abundantly observed, and others in many localities the world over. Their presence adds to the interest of the pegmatites in relation to what we have regarded as veins.

While I have thus far adhered closely in the discussion to the typical dikes or veins or dike-veins of pegmatitic and its siliceous extreme the associated quartz vein, there is still another extreme of the pegmatite exhalation or differentiation which is scarcely less important in connection with reasoning about ores. I refer to the wonderful penetrating power of pegmatitic matter into neighboring bodies of stratified or foliated rocks. For a fairly long series of years we have been accustomed to the phrase “ lit- par-lit ” injection, meaning thereby that pegmatitic matter wan- ders outward along bedding planes or foliation surfaces and is precipitated as small lenses, eyes, or even fairly well developed, so-called porphyritic feldspars. The Manhattan schist, at the moment beneath our feet, is filled with these injections of all sizes up to a few feet in length. They favor especially the small folds of extreme compression and almost circular or ring-like doubling back of the beds on themselves; but they are every- where in the schist. They consist of feldspars both red and white, of quartz and of coarser mica than that of the schist.

At times they contain less frequent minerals, such as apatite, garnet, tourmaline, dumortierite and even chrysoberyl. The dumortierite is of special interest because of its relatively high percentage of fluorine.

Our still lower-lying Fordham gneiss, without doubt the local equivalent of the Pochuck gneiss which we shall see tomorrow at Franklin Furnace, has been shown by my colleague, Professor

712 James Furman Kemp.

Berkey, to be such a complex intermingling of old sediments and of matter injected from intrusives, that even with the microscope one can hardly separate the two. A “soaking” with what we have described as the “ juice of the magma’”’ is our only satis- factory explanation of these phenomena. At the Chicago meet- ing of the Geological Society in 1920, at the joint session of our Society with it, I brought up an Idaho case where there is an ex- tended exposure of a rock which had been mapped as a gneissoid, porphyritic granite, but which was originally a thinly foliated normal mica schist, later soaked with pegmatitic matter along an intrusive granite contact. The soaking gradually faded out half a mile away from the contact into normal and not visibly affected schist. Observations proving the thesis could be satisfactorily made and clearly traced both on the surface and in the under- ground workings of a gold quartz vein which cut across the foliation.

At the Ann Arbor meeting of the Geological Society, and at the joint session with our Society, I showed a series of lantern slides taken from the foundations of these University buildings.” Our foundation stone is the Stony Creek granite, which is quarried about ten miles east of New Haven, Conn. Around the edges of the intrusive mass and well in from its border the gran- ite contains many included fragments of the older hornblendic, possibly somewhat micaceous schist or gneiss. The inclusions of the older rock through which it has forced its way are to be de- tected in the cut blocks of the University foundations, and can be traced in a series from sharply angular fragments, through others slightly rounded, corroded and split apart, to others penetrated through and through with pegmatitic matter until as the extreme stage only a ghostly foliation in abnormally coarsely crystalline granite remains. If we had not the series we would never sus- pect the cause of the localized foliation. The dark silicates of the inclusions each time are worked over into coarse biotite, some- times, although rarely, with notable magnetite. One cannot re- sist the inference that the pegmatitic juices of the granite tend to

12 The address was delivered in Schermerhorn Hail, Columbia University.

The Pegmatites. 713

gather about an inclusion, or if it is a large one, to harbor unde St 16 eee its lee, so that the inclusion or xenolith seems to act in a way a e a catalyser or precipitant and in the end may be itself destroyed. 3X In the paper offered for this meeting by J. S. Brown on the “Graphite Deposits of the Ashland District, Alabama,” the constant and important presence of introduced quartz in addition to that native in the rocks is shown beyond question. Intrusive granite is not far distant as well as more basic igneous rocks. Pegmatites and related quartz veins also do not fail. We are reminded as well of Joseph Barrell’s important paper in which he brings out the evidences of the influence of intrusives in cer- tain New England metamorphics which were not suspected by the early observers to have been affected in this way. One of the most important of all the contributions made in North America, along these lines, resulted from the studies of F. D. Adams and A. E. Barlow in the Haliburton-Bancroft area of central Ontario,” which were summarized by F. D. Adams as cited below.” Dr. Adams shows that along the great intru- sions of granite into Grenville limestones three products result :

(a) The alteration of the limestones into masses of granular, greenish pyroxene rock, usually containing scapolite, or into a rock consisting of a fine-grained aggregate of scales of dark brown miea.

(b) Intense alteration of the limestone along the immediate contact into a pyroxene gneiss or an amphibolite.

(c) ... In certain cases the granite dissolves or digests the invaded rock, after having altered it in one or other of the ways above mentioned.

The alteration products of Class a@ may be considered as due to the heated waters or vapors given off by the cooling magma, that is to be of pneumatolitic origin, while the alteration products of Class b result

13 This process is remarked in the paper by the writer on the “Granites of Southern Rhode Island and Connecticut, etc.,” Bull. Geol. Soc. Amer., 10: 371, 1899. The supposedly “ basic segregations from the magma” are doubtless the more thoroughly digested inclusions.

14 Relations of Subjacent, Igneous Invasion to Regional Metamorphism, Amer. Jour. Sci., Jan., 1921, 1-19; Feb., 174-186; Mar., 255-267.

15 F. D, Adams and A. E. Barlow, “ Geology of the Haliburton and Bancroft Areas, Prov. of Ontario,” Can. Geol. Surv. Memoir 6, 1910.

16 F, D. Adams, “ On the Origin of the Amphibolites of the Laurentian Area

of Canada,” Jour. Geol., 17: 1-18, 1909, especially p. 7.

714 James Furman Kemp.

from the more immediate action of the molten magma itself. The prod- ucts of these two classes of alteration, however, have much in common and naturally pass into one another.

The rocks of Class a also contain a variety of other minerals such as black mica, hornblende, epidote, garnet, sphene, spinel, zircon, tourmaline, pyrrhotite, pyrite, molybdenite, calcite, apatite, quartz and feldspar. The effects are shown not only near the large intrusions but also where thin sills and dikes wander off in lit-par-lit injections for impressive distances from the parent mass. The assemblage of minerals is strongly pegmatitic in character and the instances bring out the close connection between true pegmatites and the results of contact metamorphism. Chemical analyses demonstrated the introduction into the lime- stone of silica, alumina, iron oxides, magnesia and the alkalies.

If, now, we imagine a mineral such as auriferous pyrite, or a copper-bearing sulphide added to the “ juices of the magma ” there results a wide encircling area of possible impregnation around the intrusive. Specially favorable calcareous beds, such as we find in the Homestake Mine at Lead City, S. D., exercise an important selective influence as has been recently shown by Sidney Paige.”

I am not at all pnmindful that in citing these matters I am in close accord with much that is emphatically set forth by J. E. Spurr as the result of life-long observations recorded in the recent work, “ Ore-Magmas;” nor am I unmindful of the generaliza- tions of B. S. Butler and his associates after their comprehensive studies of the ore deposits of Utah.** It is, however, no lessen- ing of the credit due all the observers whom I have cited that step by step and independently others have been approaching the same goal. As to just where we may draw the line, if we do feel impelled to draw a line, between so-called igneous phenomena and so-called aqueous, or ordinary solution phenomena, there is an interesting question which I will reserve for the conclusion, having still an additional case or two to cite.

17“ The Geology of the Homestake Mine,” Econ. Grot., 18: 205-237, 1923.

18 B. S. Butler, “ Relation of Ore-deposits to Different Types of Intrusive Bodies in Utah,” Econ. GEOL., 10: 101-122, 1915.

tv

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The Pegmatites. 715

In the explanation of at least some of the magnetic iron ores in gneissic regions, processes for the introduction of the iron oxide akin to pegmatites have been advocated with much reason. No doubt can longer exist in the mind of any well-informed stu- dent of contact metamorphism that magmas give forth vast quantities of iron, perhaps as ferrous and ferric chlorides or fluorides, which are precipitated by bordering limestones as magnetite and sometimes specularite. That great quantities of silica and other bases than iron, such as magnesia, alumina and the alkalies may also be derived from the same source is equally shown by the associated silicates. The latter emissions seem to precede the former, and are of the nature of normal pegmatite. The separate emissions of the iron compounds are less frequent, perhaps, but are far from uncommon. At the Cornwall Ore Banks of Pennsylvania, the amount of ore in the contact zone is impressive in the highest degree. If to the well-attested observa- tions of these two contrasted emissions we add the penetrating ability just described for the lit-par-lit injections and the possibil- ity of their encountering replaceable beds, we have an explana- tion of the very difficult magnetite lenses well worthy of re- spectful attention. W. S. Bayley has used the conception with convincing effect for some of the New Jersey magnetites and for those of western North Carolina. My colleague, R. J. Colony, as he has verbally set forth at this meeting has added to the above outline two other conceptions. He has shown the abundant presence of intrusive granites and related igneous rocks in southeastern New York, and their assumption of the sill- form. They have penetrated into the ancient Grenville sedi- ments and have enclosed great blocks of them. Some of the ore bodies have originated by the replacement of these older sedi- ments with magnetite. Side by side with this action is the ex- tensive development of pegmatite, which in instances has been itself shattered and impregnated with magnetite, the two having

19 “Tron Mines and Iron Mining in New Jersey,” N. J. Geol. Surv. Final Re-

port, vol. 7, 1910. Compare also F. F. Grout, “ Magnetite Pegmatites of Northern Minnesota,” Econ. GEoL., 18: 253-269, 1923.

716 James Furman Kemp.

entered in the order mentioned above. Professor Colony de- scribes these phenomena as due to a further differentiation of the pegmatitic differentiate into a siliceous portion and a basic.”

In the Adirondacks and especially at Mineville, we find as- sociated with the magnetites and along the foot-wall or at the pinching places in the bed-like ore-bodies, marked developments of coarsely crystalline hornblende, pyroxene, plagioclase, biotite, less often garnet, scapolite, titanite, magnetite and less common minerals, whose individuals may attain unusually large size. Even calcite does not fail as a filling between crystals. These aggregates the Scandinavians call skarn as they are common in Sweden. One thinks of them at once as pegmatitic in nature, even though much of their substance may have been native to the wall-rocks. At Palmer Hill north of Ausable Forks and just be- low the large magnetic ore-body, D. H. Newland found the gra- nitic foot-wall rich in fluorite as a component mineral, affording a rock akin to the trowlesworthite of the British petrographers.” In the magnetite mines molybdenite is not uncommonly met in the pegmatitic developments and from the Ogden Mines of New Jersey, a few miles east of Franklin Furnace, unusually fine and large crystals have been obtained.

A rarer and peculiar phase of pegmatites differing from the normal has been described by Samuel G. Gordon as “ Desilicated Granitic Pegmatites.” By the name, dikes believed to be of pegmatitic nature are described but which from penetrating basic rocks such as serpentine or peridotite lack quartz and the highly siliceous minerals and become changed in the one case to the albitite of H. W. Turner and in the other to the plumasite of A. C. Lawson, an oligoclase-corundum rock. Instances are cited from the eastern states in addition to those from California. Reactions of acidic pegmatite with the basic wall-rock are be- lieved to yield the intermediate varieties.

20“ Magnetite Iron Deposits of Southeastern New York,” Bulletin 249-250. N. Y. State Museum, 1923.

21 “ Geology of the Adirondack Magnetic Iron Ores,” Bulletin 119, N. Y. State Museum, p. 100, 1908.

22 Proc. Philadelphia Acad. Sci., 1921, Part I., 169.

The Pegmatites. 717

The early observers of phenomena related to the pegmatitic processes noted here and there in Saxony and in Cornwall, the impregnation of schists or other rocks neighboring to granite, now with tourmaline, again with topaz. The descriptions of these phenomena usually follow the pages on granites in the for- eign textbooks and come next after the remarks on pegmatites. In the monumental work of Ferdinand Zirkel, which is a mine of petrographic lore, they will be found set forth with painstaking care. The famous breccia which is charged with topaz at the Schneckenstein, near Auerbach in southern Saxony, has furnished from its vugs crystals of this mineral with which generations of students have been drilled in crystallography. The luxullianite of Cornwall displays a coarse feldspathic rock whose components are replaced and penetrated with radiating rosettes of tourmaline needles, making one of the delights of microscopic study. I need only mention also the greisen or zwitter of the Saxon tin miners, those aggregates of quartz and fluorine-bearing micas which were favorable to cassiterite.

When the tunnel for the Catskill Aqueduct passed along St. Nicholas Ave. at 135th Street, New York, and several hundred feet beneath the surface, it intersected an area of Manhattan schist well provided with pegmatite dikes. One of these a foot or a foot and a half in breadth was displayed in the walls for several hundred feet. Under the guidance of J. F. Sanborn, C.E., of the Aqueduct engineers, Professor Berkey and I spent one evening studying its peculiar features. At several places and at intervals of ten yards or more, the dike was crossed perpen- dicularly by later veins of clear, glassy quartz, an inch or two wide. The quartz appeared to fill contraction cracks or some- thing of the sort, as if it were the last dregs of the magma. Where these cross quartz veins met the mica schist of the coun- try rock, and on each side, innumerable tiny needles of black tourmaline radiated outward into the schist for six inches or more. They practically replaced the schist or penetrated it through and through with their shining crystals and they seemed to represent the very last boracic and fluoric exhalations of the

718 James Furman Kemp.

magma of the dike, from the cross-fractures probably filled at the time with gelatinous silica. Tourmalinization is a not un- common process in some metalliferous deposits, not alone those containing tin, but also some yielding copper, and others produc- tive of gold.

The temperature of the closing pegmatitic crystallizations may be inferred from the nature of the quartz. In June, 1909, F. E. Wright and E. S. Larsen published an interesting paper on “ Quartz as a Geological Thermometer ” (Amer. Jour. Sci., June, 1909, page 421). Quartz, as we will all recall, has a reversion point at about 575 degrees C., so that, as the temperature rises, the crystal structure changes at this point from the trapezohedral- tetartohedral to the trapezohedral-hemihedral. The etch figures are different and are characteristic of each form. In the study of the Mineville magnetites and while preparing in 1909 the Bul- letin 138 of the New York State Museum, already referred to, I asked the aid of Dr. Wright toward gaining an idea of the temperatures involved in their formations. Five plates of quartz from the associated skarn were prepared and gave etch figures in which three had the characters of the quartz below 575° C. and two those of the variety above this temperature. Dr. Wright inferred that the quartz on the whole rather favored the low temperature variety formed near the critical point, 575° C. Seven plates were prepared from a drill core seventy-two feet be- low the ore and from the rock considered to be a typical case of the quartz-bearing syenite forming the wall-rock. Five favored the high temperature variety, and two the lower. The conclusion reached was that these quartzes were probably formed not far from the critical temperature, 575° C. Ten plates were cut from another core at some distance from the mines. Five were the high temperature variety, and five the low. Seven plates were prepared from the lean quartzose ore from the Nichols Pond Mines some miles from Mineville. All the tests indicated that the quartz had never reached 575°

23 Bull. 138, pages 130-132, 1910.

The Pegmatites. 719

In the pegmatite dikes is also much microcline, and microcline has a somewhat poorly established reversion point to orthoclase under surface conditions of about goo° At 1170° C. ortho- clase is resolved in the laboratory to a liquid and to leucite. For the dikes we may, therefore, have some confidence in a tempera- ture between these extremes and probably, under the influence of dissolved gases and deepseated pressure, not necessarily far above 575° ©.

We have reviewed enough, perhaps, of the characteristic phe- nomena of the pegmatites and their related processes to enable us to take up in conclusion the much mooted question as to whether, using the phraseology of our predecessors, we should consider them igneous rocks and phenomena of fusion, dikes in other words; or whether we are dealing with solution phenomena, that is, veins; or thirdly whether we can draw any sharp line of de- markation as between phenomena of fusion and those of solu- tion. Have we not been inclined to stress the supposed contrasts between these two unduly?

In 1892, after reviewing all the known previously published classifications of ore-deposits, I proposed a genetic one, having three grand divisions: I., Of Igneous Origin; II., Deposited from Solution, and III., Deposited from Suspension. In 1894, Professor W. O. Crosby attacked the same problem and proposed Deposits—A, Of Igneous Origin; B, Of Aqueo-igneous Origin; C, Of Aqueous Origin. place was thus provided under B for the pegmatites with whose special study Professor Crosby was then actively engaged. The suggestion was an excellent one, and the descriptive phrase aqueo-igneous perhaps sums up, as well as it can be done, the peculiar features of these mineral deposits, coming as they undoubtedly do, between those which I sought to describe as “I., Of Igneous Origin, and those, II., Deposited from Solution.”” Yet other troubles were also in store for this last named two-fold division.

Early in petrographic studies with the microscope, observers

24H, L. Alling, “ The Mineralography of the Feldspars,” Jour. Geol., 31, May— June, 1923, 291-206.

720 James Furman Kemp.

noted that in the crystallization of igneous rocks there sometimes remained a glassy residue, which was called “ basis” and was in a way regarded as the surviving and quickly chilled, so to speak, mother-liquor. This glassy “basis”? was also called magma and you may recall that the extremely low silica basalts with a glassy groundmass, called limburgites by Rosenbusch in 1872, were just a little earlier in that year named magma-basalts by Boricky. Fifteen years later in 1887 came the important in- vestigations and experiments of Lagorio, with the glass-basis,

leading to the conception that a molten magma is a solution of some compounds in others; that the compounds crystallize out in the order in which they, as solutes, saturate the rest of the still fluid magma, which is the solvent. Finally remains the glass. The bearings of these and other investigations were summed up and made available for American students by the two great es- says of J. P. Iddings, “The Crystallization of the Igneous Rocks,”’ read before the Philosophical Society of Washington, May 25, 1889, and “ The Origin of the Igneous Rocks,” read May 7, 1892. In 1898 came the further “ Experimental In- vestigations on the Crystallization of Minerals in Magma” of Jozef Morozewiez, in the carrying out of which he had the help of crucibles and furnaces used in glass-making and, therefore, of large melts. We all came to realize that our igneous magmas were solutions just as much as the water-solutions which, we had always imagined, had filled our mineral veins. When in 1913, Professor Lindgren published his invaluable treatise on Mineral Deposits, and when he came to discuss their classification, he acutely remarked after summarizing my early attempt: “ Diffi- culties appear here too, for what are igneous magmas but solu- tions.”” He then leads up to the scheme with which we are all familiar and which summarizes the many important contributions in which he had for years stressed the great influence of the physical factors, heat and pressure.

And yet there are some important contrasts between normal igneous cooling and crystallization on the one hand, and deposi- tion of vein fillings from water-solutions, as we ordinarily con-

The Pegmatites. 721

ceive them, on the other. In the majority of igneous consolida- tions, especially in the varieties of igneous rocks possessing medium and low percentages of silica, we have cases of relatively dry fusion. The solidified dike represents almost if not quite all of the original fused substance both solutes and solvents. Per- haps some dissolved gases have escaped but the evidence of them is not impressive. On the other hand, in our typical mineral vein which we imagine to be filled from predominant water solution, the solute has crystallized out and the solvent has passed on else- where. Even in the quartz dike-veins which J. E. Spurr con- ceives as injected in the form of gelatinous silica, we must pro- vide for the elimination of I2 or 14 per cent. of water before quartz can result. In this case we are not so far from our old conceptions of the origin of quartz-veins, or other veins as we might at first seem.

There is also another consideration which is worthy of at- tention. In 1896 when I felt compelled to prepare a Handbook of Rocks in order to provide my students with a suitable modern textbook, I found myself logically driven to consider water or its consolidated form, ice, as a good igneous rock of a very low fus- ing point. And so water and ice were placed at the far end of the table of igneous rocks, where the rare ultra-basic varieties with little or no silica were to be found. To a certain extent water as an igneous rock may seem to be a matter of casuistry because we draw our distinctions on the basis of ordinary experi- ence with temperatures and pressures, and the very word igneous implies for us great heat. I am not anxious to prove, for ex- ample, that the secondary enrichment of copper ores, wrought at ordinary temperatures by the downward trickling of the igneous rock, rain-water, is to be classed with igneous phenomena. Nor will I urge the further point that air is an igneous rock, normally gaseous, but liquifying and solidifying toward or below the so- called absolute zero. Nor need I remind you that at the other extreme, all our fancied solids and liquids might be gases in the sun, for whose high temperatures even the word igneous would be feebly descriptive.

722 James Furman Kemp.

But in seriousness, I would emphasize the fact, that from cases of relatively dry fusion, 1.e., fusion without the presence of in- fluential amounts of dissolved or involved water gas and other mineralizers, we may pass through successive stages of greater and greater richness in dissolved gases and liquids, which when the magma consolidates, escape with a burden of dissolved matter for vein-formation. These escaping solutions may mingle with greater and greater proportions of meteoric groundwaters until we find ourselves in grave difficulties if we try to draw an arbi- trary line between the two.

The pegmatites mark a stage which closely follows the con- solidation of true, normal igneous rocks, generally of granitic composition. The parent magmas of them must have been re- latively rich in dissolved gases. The pegmatitic differentiate represents a concentration of these gases in a comparatively small portion of the parent magma. The pegmatitic differentiate departs in a highly fluid condition and, of necessity, from its composition under great pressure. It must be extremely fluid in order to possess the penetrating power which it has been shown to have. The same conclusion regarding its fluidity follows when we try to imagine conditions favorable to the growth of the huge crystals, many involving the rare elements. When the nuclei of growth for these gigantic crystals were established, the substances necessary to their growth must been attracted from a wide sphere of influence. Convection currents may also have aided. In the crystallization of the pegmatitic magma, further differentiation sometimes resulted in banded structures and in concentric zones of contrasted mineralogy. Quartz is commonly the last of the abundant components to consolidate, and a very siliceous differentiate with correspondingly abundant gases and liquids, and extreme mobility may easily have been given off to fill fissures, a matter of very early observation. Where or when in its wanderings the lost differentiate ceased to be a magma and became an aqueous solution, no one can readily decide.

There is good evidence for the conclusion that after the sili-

The Pegmatites. 723

ceous pegmatitic emissions had departed from the parent magma, iron-bearing and highly basic emissions followed. The resulting bodies of magnetite are not necessarily limited to contact zones in limestones. If not intercepted by limestones, they might travel the lit-par-lit trails a long distance from their starting points.

CoLuMBIA UNIVERSITY, New York City.

Supergene Enrichment Of Copper Below A Lean Pyritic Zone.’

Charles Henry White.

THE important high-grade ore-bodies of the Cananea district, Sonora, Mexico, are confined to a zone about half a mile wide and six miles long, running northwesterly through the Cananea Mountains.* On the south side of this zone near its southerly end a typical “ porphyry ” cropping covers an area of about four square miles on the Cerro de Cobre and its foot hills. The area is occupied in the main by long even slopes which rise from about 5,300 feet in the extreme south to 6,900 feet at the crest of Cerro de Cobre. The slopes steepen as the ravines are ap- proached often to more than thirty degrees and occasionally they are broken by nearly vertical cliffs. In considerable areas the solid rock outcrops, but the surface is usually covered with float from a few inches to a few feet in depth which supports a moder- ate growth of scrub oak and other shrubbery.

The rocks of this area consist of diorite porphyry into which has been intruded numerous bodies of quartz-monzonite porphyry, the latter appearing in about one-fourth of the area. Emmons and his associates made a thorough study of the whole district and concluded that a period of mineralization followed the in- trusion of both the diorite porphyry and the quartz-monzonite porphyry; but in the area here considered I found no evidence of mineralization prior to that which followed the intrusion of the quartz-monzonite porphyry. The primary mineralization was pyritic and well disseminated. In the process of mineraliza- tion the sulphides attacked first the ferromagnesian minerals and

1 Published by permission of Mr. T. Evans, General Manager, Cananea Con- solidated Copper Company.

2Emmons, S. F., “ Cananea Mining District, Sonora, Mexico,” Economic GE- OLOGY, 5, 312 (1910).

3 For a full description of these rocks see Emmons, op. cit., pp. 325, 329.

metallization was not more than one or two tenths of one cent.

Weathering and leaching have produced the usual limonite- stained cropping, the limonite, kaolin, sericite, quartz, and feld- spar varying in quantity from place to place. At a few points near the top of the mountain molybdenite occurs in the cropping, and in certain ravines pyrite appears at the surface.

In two places about a mile and a half apart on this large min- eralized area drilling has revealed interesting bodies of second- arily enriched disseminated ore which occupy a very unusual posi- tion with reference to the top of the sulphide zone. It is not un- usual to find in such deposits a thin zone of impoverishment just below the oxidized zone, but in the area under discussion a zone of low enrichment more than a hundred feet in thickness lies be- tween the bottom of oxidation and the top of the ore. One of these bodies which has been explored by drilling for a distance of at least a thousand feet from north to south has been cut by twelve drill holes, and the average thickness of lean sulphide above the ore through which these holes passed is 121 feet. The other body, one and a half miles to the north and higher in the mountains, has been cut by five drill holes which passed through a lean pyritic zone above the zone of commercial ore, averaging 160 feet in thickness and carrying on an average 0.56 per cent. copper.

Table I. below shows for each of the seventeen holes the eleva- tion, the depth of oxidation, the thickness of the lean sulphide and its average content as far as data are available, and the depth at which ore of commercial grade begins. Holes Nos. 1 to 12 inclusive are in the ore-body in the southern part of the area, and the remaining five holes are in the northern ore-body.

To show the nature of the mineralization condensed logs of holes Nos. 11 and 12 are given below. They have been selected

Charles Henry White.

because the determinations for iron and sulphur as well as for It should be stated that the iron content in

copper are available.

the oxidized zone of hole No. 11 is much above the average, and also that its content in copper is below the average, while the content in copper for hole No. 12 is above the average.

TABLE I. Hole No.

ae! ee VU RSE Elevation (approximate). . .|5,850]5,725|5,72515,725|5,025|5,025|5,025|5,725 5,725|5,650

Hole No. Average

II r2 13 74 425 76 ay Elevation (approximate) . . .|5,901|5,713|5,842|6,017|6,069|5,960/5,863 Thickness of oxidized zone..| 295] 210} 20] 150 20; 20 Thickness of lean sulphide..}| 115} 120] 120] 155} I90| 160] 175 133 Per cent. copper in lean

MIMOM boon crews as oie ahs 0.61] 0.77] 0.62] 0.45] 0.53] 0.60] 0.62 0.60

Depth to top of ore zone...} 410} 330] 140 305} I90} 180] 1905 TABLE II. Convensep Loc or Hote No. 11.

Depth (Feet). |Thickness (Feet). Copper %. Iron %. Sulphur %.

a. bE 275 0.00 8.0 0.00 le 20 0.00 5.6 i 4 205-410 IIs 61 4.0 2.2 BLO=5ES os sos 135 1.20 2.8 2.3 545-790 245 -64 3.2 2.6

ConpDENSED Loc or Hore No. 12.

D=I90 .isssses 190 0.00 2.8 0.00 100-210... ...45 20 sc3 2.2 6 B00=330. . .005<5 120 77 2.9 2.7 BSOGEBO... wes I50 2.40 3.6 3-9 PLO + as 95 -52 4.6 4.4

Supergene Enrichment Of Copper. 727

It will be noted that the copper enrichment continues below the zone of commercial ore to the bottom of the holes, the average in copper for the last 245 feet of hole No. 11 being 0.64 per cent., and for the last 95 feet of hole No. 12, 0.52 per cent. The last six samples (five feet each) of hole No. 11 assayed in copper as follows, beginning thirty feet above the bottom: 0.88, 0.61, 0.75, 0.59, 0.56, 0.51; and the last six in hole No. 12 carried 0.51, 0.32, 0.32, 0.29, 0.19, 0.19. The averages for the last hundred feet of the five holes of which data are available are 0.52, 0.71, 0.46, 0.47, 0.48-——the average for the five being 0.59 per cent., which is practically the same as the average for the lean sulphide zone above the ore (.60).

Examination of the drillings under the microscope shows that chalcocite enrichment persists to the greatest depths reached by the drill, and it is believed that most of the copper is present as chalcocite. The presence of chalcocite on grains of pyrite in samples of drillings running less than 0.2 per cent. copper indi- cates that the primary metallization in copper is probably not more than 0.1 of one per cent.

These ore-bodies may be regarded as restricted zones of super- enrichment in a zone of slight enrichment which extends from the bottom of oxidation to the water level, the ore-zone occupy- ing one third or one quarter of the total thickness of the zone of enrichment and carrying from two to four times as much copper per ton as the lean zones above and below.

At certain points in the larger of the ore-bodies the drill passed through thir zones of oxidized material well down in the sulphide zone, in places even below the ore; and one of the deepest holes drilled in this area was in partially oxidized material when the hole was abandoned at a depth of 715 feet. These streaks of oxidation show that there are occasional fissures extending down at oblique angles to great depths, which might in certain cases explain enrichment below lean pyritic material, but it is not likely that oblique fissures alone could account for the uniform condi- tion found in the seventeen drill holes in such widely separated areas.

728 Charles Henry White.

An explanation of this unusual condition is suggested by the elevated and dissected peneplain surrounding the Cananea moun- tains and also by the deep water level. This tilted peneplain in- tersects the steep mountain slope at an elevation of 5,500 feet on the south and east sides of the mountains and falls away from the mountains at the rate of about two hundred feet per mile. The drainage has dissected the peneplain to depths of fifty to more than 350 feet, depending upon the distance down stream from the source. Most of the streams flowing out of this min- eralized area have cut through beds of limonite whose upper sur- faces lie in the peneplain. The limonite beds vary in character from coarse conglomerate cemented by limonite to complete re- placement of boulders and rock in place by high grade iron ore. During the period of peneplanation the streams occupied the same valleys that they now occupy but the valleys were wider and shal- lower than now. The source of the iron oxide was the sulphides in the mineralized mountains above. The iron that was not com- pletely oxidized in place was brought down in solution to the grade of the peneplain as sulphate, where under slower move- ment the iron was oxidized and precipitated as limonite, the sul- phate radical forming soluble sulphates with the basic elements of the enclosing rock. Of the copper removed in solution from the zone of oxidation probably most of it was carried down and reprecipitated in the sulphide zone but a little escaped in solution with the iron since small amounts of copper are now found in all of the many beds of limonite tested.

The upward movement of the district, and the corresponding drop of the water level (which bears no definite relation to the top of the sulphide zone and is more than a hundred feet below the bottom of the ore zone) are facts upon which hypotheses may be based to account for the peculiar position of the ore in the sul- phide zone. These facts suggest that the rate of the descent of the water level was much slower while the zone of enrichment was passing down through what is now the ore zone than when passing through the zones above and below the ore. That is, the elevation of the district after the formation of the peneplain may

Supergene Enrichment Of Copper. 729

be divided into three periods: (1) a rise of 150 feet or more at a moderate rate; (2) a continued elevation of about the same amount at a rate only one quarter to one half as rapid as during the first period; and (3) a return to the rate of rise of the first period, which may be still going on.

In the Kyshtym deposits in Russia a zone of impoverishment occurs in the upper part of the sulphide zone above the ore, but under conditions contrasting strongly with those at Cananea. At Kyshtym there is no secondary enrichment, the top of the sulphide zone is eighty feet below the water level and most of the copper has been dissolved from the primary sulphide to a depth of about forty feet in the sulphide zone where the ore begins. Not only has the copper been dissolved from the pyrite to a depth of forty feet but the pyrite itself has been dissolved and all the iron removed from a zone extending from the bottom of oxida- tion to eighty feet below the water level, leaving only baritic sand.

At Cananea the copper is nearly all supergene; the top of the sulphide zone is several hundred feet above the water level; and the difference between high and low copper content is due to deposition instead of solution.

4 Stickney, A. W., “ The Pyritic Copper Deposits of Kyshtym, Russia,’ Eco- NOMIC GEOLOGY, 10, 593 (1915).

MILts BuILpING, San Francisco, CAL.

Role Of Heavy Minerals In The Coalinga Tertiary Formations.

R. D. Reed.

Unper favorable circumstances the heavy minerals of sediment- ary rocks can without doubt be successfully used in the work of correlating formations and zones in a formation. There is still a danger, however, that progress may be somewhat delayed, es- pecially in the application of the method to the oil-industry, by the unsuccessful outcome of some poorly planned ventures in this new field. In order to assist in defining the limits within which success may reasonably be sought, I propose to discuss in this paper the geologic relations of the heavy minerals that occur in certain Tertiary formations of the Coalinga district in Cali- fornia.

To make clear the broader relation of the rocks studied, Figs. 71 and 72 and Table I. are presented.” It may be said in addition that the San Joaquin Sea must have occupied approximately the area of the present San Joaquin Valley, but with different and shifting borders. The adjacent land areas occupied the same positions as the present Coast Ranges and Sierra Nevada, but varied greatly at different times in height and form. The cli- mate changed gradually from tropical in Eocene time to arctic in the Pleistocene and warm-temperate at present.* During Plio- cene time the shallow sea apparently became filled to sea-level, and its place was taken, in part at least, by a freshwater lake. In this lake and about its borders accumulated a great thickness of clay,

1Cf. the following articles: Milner, H. B., “The Study and Correlation of Sediments by Petrographic Methods,” Mining Mag. vol. xxviii, pp. 80-92, 1923. Tickell, F. G., “The Correlative Value of the Heavy Minerals,” Am. Assoc. Pet. Geol. Bull., vol. viii, pp. 158-168, 1924.

2 For geological map see Plate I., U. S. Geol. Surv. Bull. 398.

2aJ. P. Smith, “Climatic Relations of the Tertiary and Quaternary Faunas of the California Region,” Cal. Acad. Sci. Proc., IX., 123-173, 1919.

aS

Table I.

Coalinga Tertiary Formations.

Summary oF HistoricaL DEDUCTIONS 1N REGARD TO COALINGA TERTIARY.

How Ended. é

Source of Detritus.

Climate.

Depth.

Tulare (Plio- cene).

Strong folding movements.

Early Tertiary, Cretaceous and Francis- can rocks.

Cool temper- ate. :

Lakes and streams.

Etchegoin (Plio- cene).

Gradual filling of San Joaquin Sea.

Same as above.

Warm tem-

perate.

Shallow inland sea.

Santa Margarita (Miocene).

Emergence and local erosion.

Pelagic organ- isms, Cretace- ous and Fran- ciscan rocks.

Sub-tropical.

Same as above.

Temblor (Mio- cene).

Erosion inter- val.

Same as Etche- goin (some pelagic organ- isms locally).

Tropical.

Same as above.

Kreyenhagen (Oligocene?)

Emergence and local folding.

Pelagic organ- isms and Cre- taceous rocks.

Tropical?

Land-lockt sea, depth un- known.

Avenal (Eocene).

Gradual change from deposi- tion of sand- stone to depo- sition of dia- tomite.

Cretaceous sedi- mentary rocks.

Tropical.

Shallow sea.

sand, and gravel, not very different from the alluvium accumulat-

ing over the valley floor at the present time.

During the whole

Tertiary period there have been frequent more or less local dias- trophic movements, resulting in such phenomena as faults, folds, and local unconformities.

These movements still continue.*

Definition And Classification Of Heavy Minerals.

In spite of its impropriety the name “ heavy mineral ” (French “minéral lourd’”’) is now well established as a class designation

3 For excellent published accounts of the geology of the Coalinga district, see Arnold and Anderson, “ Geology and oil resources of the Coalinga District,” U. S. Geol. Survey Bull. 398, 1910, or Nomland, J. O., “The Etchegoin Pliocene of Middle California,” Univ. Calif.

Pub. Geol., vol. 10, 1917.

732 R. D. Reed.

for those minerals with specific gravity higher than about 2.9. The class includes a large number of: species most of which are very rare as detrital constituents. The important detrital min- erals may be divided into three groups. One group consists of

TP" Drop sondstone ond sondy shole (Vocel.tes*)

‘

Dletomite imbedded in sondstone

Fic. 71. Columnar section of Tertiary Formations of the Coalinga District.

minerals that are not very stable under ordinary weathering con- ditions, but very abundant as primary constituents of many igneous and metamorphic rocks. Prominent members of this group are the amphiboles and pyroxenes. They are of extremely variable abundance as detrital materials. The second group con- sists of such minerals as zircon and titanite, extremely stable and widely but sparsely distributed in crystalline rocks. The third group consists of stable minerals of rare or local primary occur- rence, such as topaz or andalusite. These groups of minerals, though not very sharply distinguishable from one another in all cases, are worthy of separate consideration because of their un- equal value to the student of sedimentary rocks. Minerals of the

Coalinga Tertiary Formations.

third group, even when they are much less abundant than the others, are likely to deserve most careful study.

Pre -Pliocene Tertiary

ee

aces’. fosad

RIDGE SKREVENHAGEN HILLS KETTLEMAN PLAIN te

KETTLEMAN HitLS

Structure-Section Across Coalinga District

ry

Fig.

72)

TypicaL ANALYSES OF

Table Ii.

4 sates

Structure Section across Coalinga District.

SAMPLES FROM THE COoALINGA DISTRICT.

Eocene.

Temblor. Etchegoin.

314 273 300 302

fe eter cS a a ees eee — 45) 13@° 26 8 Basaltic Bom. 6.0 cs0 secs 2}/—]—f] i? S.4 PONTE YT A eee em —- — 13 47 25 44 BP PCLAUIETIO 5. 6. oct s 5 oie 's.s 5 0 510800 a 4 — 4! Turbid (unknown) 20 a II I i 4

BISCESGRARUC so oes orci cca 5 52 6 2 32 2 ESET i SE eRe eer 72 25 I — PUM UUMEU Ses: aire, b<ac0 o's eheeue. 5.4.0.4 0 012 — 6 9 3 8 I ee os siete oR ware 1 3 — — PANRAMAUEE NR 0) <Tesate fo oles aloe we sera + aN — I -- (ie: --

RRARMME Ne De ers alae Ys, Siasho oid. wis he 2-1 I — 4 OOD ACA Ce eR tee eae — I — — SUPE SASS ee eee aah ss — —|f]-— Sree ot OS -- 2 3 4 2); — OT le eS es a re ae eet atone ]) —

“ ”

signifies absent. oe

signifies present, but missed in the count.

312-A, 319, etc., are sample numbers.

Other figures give percentages, estimated by counting 100 or

slide.

200 grains in a

Table II. shows typical analyses of samples from three Coal-

inga Tertiary formations.

The heavy minerals are arranged in

734 R. D. Reed.

three groups, corresponding to those just defined. The table shows that Eocene samples have most minerals in the second group, while both the Miocene and Pliocene samples have them in the first. None of the samples showed a dominance of the species belonging to group 3. It should perhaps be noted that “turbid” and “black opaque” are mere makeshifts, designed to receive various species difficult to identify with certainty. The former includes altered mafic minerals and probably some feldspar grains. The latter includes magnetite, ilmenite, chro- mite, and doubtless occasional grains of other minerals.

Heavy Minerals And The Erosion Cycle.

In order to show the relation of the various problems herein discussed to one another and to the principles of general geology, the problems will be discussed in the order suggested by a typical cycle of erosion. The “broad principles governing the trend of events during any given cycle of erosion involve, among others, three fundamental factors . . ., viz., the weathering of a land- mass, the transportation of the weathered material by mechanical agency, and the accumulation of that material in a suitable basin of deposition, under varying subaérial or subaqueous condi- tions.” Like the other constituents of the sedimentary rocks, heavy minerals may be examined for the light they may throw on the history of a formation. Their distribution in a forma- tion is related to some conditions and processes of the distributive province, or region of weathering, and to others of the deposi- tional basin. The various subjects to be discussed may be grouped as follows:

Problems of the distributive province. Kinds of rock. Location of province. Climate. Transporting agents.

Problems of the depositional basin. Transportation. Deposition.

4 Milner, H. B., “Introduction to Sedimentary Petrography,” London, 1923, p. 8s.

Cocalinga Tertiary Formations. 735

ae The correlation problem. AZ Ye

. Ss A Xs TN

Zones in a formation. ¢ The recognition of formations. ® nrc $ 7 DEG 15 1994

eo

PROBLEMS OF THE DISTRIBUTIVE PROVINCE. ee af

Kinds of Rock.—In regard to the kinds of rock that out- leant cropped in the distributive province that furnished detrital ma- terials to the Coalinga Tertiary formations, the conglomerate pebbles and the quartz and feldspar grains, as well as the heavy minerals, give some information. The information furnished by the conglomerates is the more readily available, and has al- ready been used.® It suggests that all the clastic Tertiary for- mations derived materials from the Cretaceous strata; that the Santa Margarita and later formations contain in addition more or less material derived from Franciscan rocks; and that the Etchegoin-Tulare detritus was partly furnished by earlier Terti- ary formations. Detailed studies, involving the comparison of thin sections of all classes of pebbles in the various conglomer- ates with thin sections of the various types of rock known in the different mountain areas of California, would doubtless furnish a good deal of additional information. If comparisons were to be made, further, of the rare accessory minerals in the pebbles and in the various primary rocks, the information would prob- ably gain considerably in definiteness.° The relevant informa- tion secured by a study of the quartz and feldspar grains in these formations is rather scant. Most of the quartz grains have fluid inclusions, but even the exceptional grains with “ regular” in- clusions have not been traced to any definite source. Even if, as seems likely to be true, these “ regular” inclusions prove useful in future investigations, it must be noticed that they are nothing more nor less than heavy minerals themselves. As Cayeux states ® the matter: ‘‘ When they [the common minerals, like

5 Arnold and Anderson, op. cit., pp. 145, 185, ete. 6 Cf., A. Gilligan, Quart. Jour. Geol. Soc., LXXV., 1919-20, p. 251. 7W. Mackie, Trans. Edin. Geol. Soc., VII., 1896, p. 148.

8L. Cayeux, “Introduction a L’Etude Petrographique des Roches Sedi- mentaires,” Paris, 1916, page 47.

736 R. D. Reed.

quartz] definitely suggest their origin, it is generally by mineral inclusions of the same nature as the heavy minerals in question.” If, then, a thorough study of the pebbles and common detrital minerals with reference to their origin requires a study of the heavy minerals they contain, no argument should be necessary to prove that the heavy minerals existing as free detrital grains in the sediments should also be studied.

In the present investigation, the study of the heavy minerals has already supplemented in various definite respects the infor- mation secured earlier from studies of the pebbles. It has shown, for example, that Franciscan rocks contributed detritus to the basin considerably sooner than had been supposed. In discussing the origin of the “ Big Blue” (an Upper Miocene formation in the region of the Coalinga anticline), Arnold and Anderson °® state: “‘. . . It is the earliest zone giving indubitable evidence of the occurrence in it of fragments of the rocks associated with the Franciscan formation.” The occurrence of abundant glauco- phane, not to mention other minerals, in nearly all samples of the underlying Temblor (Table II.), however, appears to give equally indubitable evidence that the Franciscan rocks were undergoing erosion during the whole of Temblor time. Though of no great practical importance in itself, this example illustrates vividly the advantages to be gained by at least a casual examination of the heavy minerals in a sedimentary formation.

In the study of formations which contain no conglomerate beds, the usefulness of the heavy minerals is still more apparent. The thick Kreyenhagen and Santa Margarita diatomites, for ex- ample, though entirely devoid of pebbles, are sparingly supplied with heavy minerals. So far as the examination of a few dia- tomite samples permits one to infer, Franciscan rocks were not exposed in the neighboring land areas during the deposition of the Kreyenhagen, but were exposed during the deposition of the Santa Margarita shale. And in this case, too, the lack of im- mediate practical importance of the example does not detract from its interest or conclusiveness as an evidence of the value of the heavy minerals.

9 Op. cit., page 175.

Coalinga Tertiary Formations. 737

Location of Province-—The location of the distributive prov- ince is likely to remain uncertain until the accessible portions of the various possible provinces have been investigated petro- graphically. In California such studies are still far from com- plete. Information about the heavy minerals of the various types of ancient rocks is especially fragmentary. It is therefore not to be expected that very definite conclusions can be drawn from the available data in regard to the sedimentary rocks. Whether the Eocene detritus came from lands to the east or to the west, for example, is not quite certain; it may very well have come from areas of Cretaceous rock lying toward the west. The prevalence in the Avenal sandstone of zircon and similar min- erals, and the absence of unstable species, are in harmony with this suggestion. So far as the later formations are concerned, there seems little reason to doubt that their detritus came in large part from land areas only a few miles west of the present Coal- inga district, in the region of the present Coast Ranges. Whether or not other more distant areas also contributed ma- terials to the basin, and where such areas may have been, cannot be determined at present.

With reference to the location and geology of the distributive province that furnished materials to the Tertiary formations, then, the heavy minerals have furnished distinctly valuable evi- dence. When more exhaustive data are available as to their distribution both as primary and detrital minerals, the definite- ness of the evidence is likely to be much increased. It remains to consider their suggestions in regard to the climatic conditions that prevailed in the distributive province at various times.

Detrital Minerals and Climate——The relation that is supposed to exist between the mineralogy of a sediment and the climate under which its detrital materials were weathered has been dis- cussed in many papers.*® So far as the heavy minerals are con- cerned it is obvious that only the less stable, chiefly ferromag-

10See, for example, Mackie, “ Felspars in Sedimentary Rocks as Indicators of Climate,” Trans. Edin. Geol. Soc., VII., 1896, p. 455, and Barton, D. C., “ The Geologic Significance of Arkose Deposits,” Jour. Geol., vol. 24, 1916, pp. 417-

738 R. D. Reed.

nesian types are worthy of special consideration. The others re- main unaltered under almost any weathering conditions. If a sedimentary rock contains a large proportion of ferromagnesian minerals, however, as do the Miocene and later formations of the Coalinga district, one hypothesis to account for the fact would be that the detrital materials were weathered in an arid or a cold climate, and the materials for such a formation as the Avenal sandstone, in which amphiboles and pyroxenes are almost com- pletely absent, might have been weathered in a warm, humid climate.

The absence of ferromagnesian minerals from rocks of Eocene age is counterbalanced, however, by the presence of abundant, largely fresh feldspar. In the later formations the feldspar is little if any fresher or more abundant than that in the Avenal sandstone. This fact suggests that some factor other than cli- mate is probably the cause of the difference of the formations in content of ferromagnesian minerals. Upon consideration of the problem it seemed that a test might be made by examining Eocene and Miocene sediments that had supposedly been derived from the same parent rocks; or if that proved impossible, it might help merely to examine some that were clearly derived from old rocks other than those which furnished detritus to the Coalinga for- mations. From Pack’s™ account of the Tertiary formations in the south end of the San Joaquin Valley, it was inferred that those formations might. furnish suitable samples for the test. Both the Eocene and Miocene of that area appear to have been derived from lands in the region of the present Tehachapi and San Emigdio Mountains. It seemed possible therefore that the ferromagnesian mineral content of the rocks formed in the two epochs would vary because of climatic differences, or if it did not, that the relations would at least be different from those in the Coalinga district. If, for example, the Eocene of that region should be free from ferromagnesian minerals, while the Miocene rocks should have them abundantly, the chance that ancient cli-

11 Pack, R. W., “The Midway-Sunset Oil Field, Calif.,” U. S. Geol. Survey, Prof. Paper 116, pages 23, 29, etc.

Coalinga Tertiary Formations. 739

mates entered into the matter would appear greater than before; but if the two formations did not differ in this respect, or differed in some other way, the chance would be less.

A sample of Eocene from the Tejon Ranch was therefore com- pared as to heavy mineral content with a specimen from the beds mapped by Pack as Vaqueros (Lower Miocene) in the foothills south of the town of Maricopa. This study showed that both are highly feldspathic, but the Tejon is abundantly supplied with amphibole grains while the Miocene specimen lacks them almost entirely. In other words, if these samples are typical of the for- mations from which they come, the conditions in this area are the exact opposite of those in the Coalinga district, which was part of the same basin of deposition and not much more than a hundred miles away. The chance that climate had anything im- portant to do with determining the proportions of the less stable heavy minerals appears to be considerably weakened by this test.

So far as it goes, then, the evidence suggests that the differ- ences of the various formations in heavy mineral and feldspar content should probably be attributed chiefly to changes of source. That the matter is even less simple than it seems, however, may be seen from the fact that in such a region as California the distributive province may include regions with very different cli- mates. The same river may carry feldspathic sand disintegrated on a mountain top and also the highly stable residue from rocks chemically weathered on the lower, humid flanks of the mountain. The safest conclusion appears to be that the conditions are likely to be too complex to be traced out by the means available at pres- ent. It seems evident, at any rate, that the heavy minerals do not offer any advantages as climatic criteria over the feldspars.

Transporting Agents——To learn much about the transporting agents that carried detrital materials to the basin of deposition is often a difficult matter. The degree of rounding of grains of quartz, zircon, tourmaline, etc., is certainly a measure of the amount of wear to which they have been subjected at some time during their history as detrital grains; so is the roundness of

740 R. D. Reed.

pebbles.** To consider but a single one of the complicating fac- tors, however, it is certain that sedimentary formations, such as the Coast Range Cretaceous group which aggregates several miles in thickness, have in the course of geological history so fre- quently furnished materials for younger sediments that such data as the degree of rounding of grains must be used very cau- tiously. It is not obvious, furthermore, that the heavy minerals will supplement the evidence of the pebbles and quartz grains in any important respect, unless possibly in the study of metamorphic sediments.**

By a slightly different approach to the problem, attempts ‘have been made to infer something from the proportions of mica and of the amphiboles and feldspars in regard to the transporting agents that may have carried detritus. The possession of good cleavage by these minerals is supposed to cause their elimina- tion from sands that are subject to much eolian action. There are some reasons, however, for doubting if the proposed criteria have very general validity. Dominant eolian action, for in- stance, is likely to be associated with an arid or semi-arid cli- mate, which should cause a large proportion of the ferromag- nesian minerals in the crystalline rocks to persist in the disinte- grated material. If this distintegrated material were left to long- continued action of the wind, there is little doubt that the cleav- able ferromagnesian minerals would eventually be worn so fine as to be easily carried away from the sandy regions. If the ac- tion of the wind were occasionally interrupted, however, by the short but violent rains that seem to occur now and then in all actual deserts, it seems perfectly possible that a considerable pro- portion of the ferromagnesian minerals in the weathered residue

12C. K. Wentworth, “The Shapes of Pebbles,” U. S. Geol. Survey Bull., 730, 1922, pp. 91-114. W. H. Sherzer, “ Criteria for the Recognition of the Various Types of Sand Grains,’ Bull. Geol. Soc. America, vol 21, 1910, pp. 625-662. C. L. Dake, “ The Problem of the St. Peter Sandstone,” Bull. School of Mines and Metallurgy, Univ. Missouri, vol. 6, 1921, pp. 177-185.

18J. D. Trueman, “The Value of Certain Criteria for the Determination of Foliated Crystalline Rocks,” Jour. Geol. vol. 20, 1912, pp. 244-258.

14 Goodchild, “ Desert Conditions in Britain,” Trans. Edin. Geol. Soc., VII, 1896, Pp. 206.

Coalinga Tertiary Formations. 741

might escape destruction by wind action and be carried by streams to the basin of deposition. Unless aridity were so extreme, therefore, as to eliminate water entirely from the role of trans- porting agent, it is doubtful if the resulting sediments would en- tirely lack ferromagnesian minerals from this cause alone.

In fact, as suggested above, it has been argued with some show of probability that a considerable proportion of ferromag- nesian minerals in a sediment often implies partial aridity in the distributive province, and therefore, presumably, a considerable degree of eolian action. In the more arid parts of the San Joa- quin Valley, with plenty of wind action and a mean annual rain- fall of five inches or less, the abundance of amphibole and pyrox- ene in the stream alluvium seems to favor this view of the matter.

It must be admitted, in conclusion, that the heavy minerals do not at present serve to give us any very definite information about the agents that transported the detritus of a sedimentary rock. So far as the rocks discussed in this paper are concerned, the heavy minerals add practically nothing to our knowledge of the transporting agents. Everything that is known about these rocks, including the nature and slight rounding of many of the pebbles and the high degree of angularity of the quartz grains, suggests that the material was carried by short streams from the region of the present Diablo Range or other nearby areas. The character of the heavy minerals, though consistent with this view, confirms it only indirectly.

Problems Of The Depositional Basin.

Transportation.—In the making of marine or lacustrine de- posits there is commonly an important amount of transportation by currents after the material reaches the basin of deposition. Upon this process and some changes in the distributive province, as will be discussed below, depends the distribution of the various heavy minerals in a formation, and consequently the possibility of correlating formations or parts of formations by a study of the heavy minerals. In a discussion of the use of heavy min- erals to determine the currents of ancient seas, the matter has

742 R. D. Reed.

been admirably summarized by Cayeux."® His discussion may be translated and slightly abridged as follows:

“In addition [to certain other uses], several of these heavy minerals are means incomparably more sensitive and certain than organisms for determining currents, and their introduction into a given region is often the work of currents. Many animals whose presence has been invoked to prove the intervention of currents are endowed with their own means of locomotion. Be- sides, eggs or embryos fixed accidentally or otherwise upon swim- ming animals, can profit by. the movements of the latter and be carried to great distances from their point of origin, the cur- rents remaining absolutely without influence on their dissemina- tion. . . . [On the other hand] one may say without exaggera- tion that the study of the heavy minerals is an inexhaustible mine of information in regard to the history of the currents of the ancient seas. .’ Referring to the conditions in the Upper Cretaceous of the Paris Basin, which he has studied for many years, he continues: “ It is known that a surface current came into this basin through the Strait of Poitou and that another came down from the North. The first carried certain materials of which one finds not even a trace in the deposits of the second. To make our ideas definite, we may recall that all chalk which contains kyanite has been deposited under the influence of the current from the southwest. So true is this that the area af- fected by this current may be defined by the points where this mineral is found in the chalk. It suffices therefore to hunt for kyanite in the chalk of a certain horizon in order to get the data for a current map of that horizon. There is no doubt that we have here the principle of a method of defining the currents and their zone of influence in the ancient seas: a method called, I be- lieve, to render the greatest services to paleoGceanography.”

Deposition.—In an interesting study of the St. Peter sand- stone, Dake writes against the view that the heavy mineral

15 Introduction, p. 47. 16 For other examples of a similar use of the heavy minerals, see Boswell, Quart. Jour. Geol, Soc., LXXI., 1915, p. 536; Gilligan, same journal, LXXV.,

1919-20, Pp. 251. 17 Op. cit., pp. 221-222.

Coalinga Tertiary Formations. 743

content gives any useful information about the conditions of deposition of a formation. Instead, he states that “ the struc- tural and stratigraphic relationships in the field, including such features as the character of the bedding, cross-bedding, uncon- formities, lateral gradation and similar associated phenomena constitute the only valid criteria for determining the conditions under which a deposit was last laid down.” If among the as- sociated phenomena the author means, as is likely, to include the fossils, there is little to criticize in his statement of the case.

Sum Mary.

The relation of the heavy minerals to various stages in the his- tory of a formation has now been traced. The discussion has shown that a study of these minerals tells little about the climate of the distributive province; that it adds almost nothing to what we can otherwise learn about the transporting agents of that province, or the conditions in the basin of deposition to which the materials are carried. The study does promise, however, to give considerable information about two important matters: the ge- ology of the distributive province, and the directions of currents in the basin of deposition. The attempt will now be made, with as little repetition as possible, to point out the relation of the dis- cussion to two more or less distinct phases of the correlation prob- lem: the recognition of relatively thin horizons in a thick for- mation, and the distinguishing of one formation from another over fairly large areas. Because of its importance in oilfield work, the former phase will receive a fuller treatment than the latter, which has been more thoroughly discussed in most earlier papers.

The Problems Of The Coalinga Formations.

In undertaking a study of the heavy mineral distribution in the Coalinga Tertiary formations, two questions seemed of prime importance. First, does a series of samples taken vertically through a formation show recognizable differences from bed to bed or zone to zone in the heavy mineral assemblages? Second,

744 R. D. Reed.

are these distinctive assemblages, if present, laterally persistent for distances of as much as one or a few miles? The order of treatment here will be to give for each question, first the relevant theoretical considerations, and second, a summary of the evi- dence as determined during the laboratory work.

Variations in the Vertical Series ——Whether or not heavy min- eral assemblages should be expected to change from bed to bed or zone to zone of a formation depends chiefly on the character of the changes that take place in the distributive province during its deposition. Consider an area of a few square miles in the San Joaquin Sea during Pliocene time. If all the materials were brought to the currents affecting the small area in question by a single river draining a region of sedimentary rocks, the first im- portant change in heavy minerals might come only when the progress of erosion uncovered locally some outcrops of crystal- line rocks; or, drainage changes of the kind that are always tak- ing place during stream development might bring waste from a different kind of rock into the drainage basin. A similar result would be reached if faulting brought above drainage rocks dif- ferent from those at first exposed. Even under the most uni- form conditions that one can assume it is therefore likely that successive strata deposited in a basin would vary somewhat in heavy mineral content.

Instead of by a single river, there is more likelihood that a small area in the basin would be supplied first by one stream, then by another. Thus a single area in the San Joaquin Sea might have received materials at one time from the Sierra Nevada, at another from the San Emigdio district, and at still another from one of the Coast Ranges farther north. A local shower in any one of these regions might cause the carrying down of material which would be drifted by currents over a great part of the Sea. Changes in the kind of heavy minerals deposited in a given place might be brought about merely by a shifting of the wind. Con- siderations of this kind make it reasonable to expect that vertical series of samples taken at intervals through a formation should show differences in heavy mineral content.

Coalinga Tertiary Formations. 745

To secure satisfactory samples from which to learn the vertical distribution of the heavy minerals was a relatively simple matter, Series were taken from the Temblor of Tar Canyon, from t Etchegoin of Jacalitos Creek, and from the Fernando, a Plioce formation similar to the Etchegoin, well exposed along Ventur River in the Ventura district. Several incomplete series were taken at various places in the Coalinga district. The investiga- tion showed that the variation of the heavy mineral assemblages from bed to bed is rather striking. In some instances, in fact, it is greater than had been anticipated, and therefore not too easy to account for. The study showed that most of the variation is in the amounts and proportions of the ferromagnesian minerals. The stabler minerals are present in such relatively small propor- tions that their mutual relations are not readily determined. In- asmuch as theoretical considerations suggested that variations in these rarer constituents are likely to be the more valuable, the two classes of minerals were separated. Separate study of the stabler minerals showed that, as had been surmised, their propor- tions differ quite as considerably as do those of the ferromag- nesian heavy minerals. It would appear therefore that in in- vestigations of this character the two classes of minerals, if both are present, should be separately studied.

This study shows that some minerals do not occur at all through great thicknesses of rock, but are common in other parts of the same formation or group of formations. Hypersthene is absent from most of the Temblor of the Reef Ridge area, but is common in the Etchegoin. Other minerals, on the other hand, are scattered through the whole series of Miocene and Pliocene rocks, but are absent or very scarce in one bed and abundant, it may be, in the next higher or lower bed. It is noticeable, further- more, that the same kinds of minerals occur, and the same kinds of variations, in both shale and sandstone.

Lateral Persistency of Heavy Mineral Assemblages.—A little investigation of recent deposits suggests that the lateral per- sistency of heavy mineral assemblages probably varies immensely according to the conditions of deposition. There is no reason,

746 R. D. Reed.

for example, to expect a high degree of persistency in alluvial fan deposits. Examination of beach sands from various points along the Pacific Coast of California shows that they, too, vary much in mineral content from place to place. It appears, in fact, that only where vigorous currents exist are the materials brought into a basin likely to be spread about with sufficient uniformity so that their rare minerals might possibly be used for correlation. Suitable conditions exist, it would seem, in many large lakes, in inland seas, and on the continental shelf of the ocean.** If this deduction is true, the Miocene and Pliocene deposits of the Coal- inga district are to be classed among the formations worthy of study in this respect.

To learn anything certain about them, however, proved to be a rather difficult task. Even in a region of excellent outcrops, the loosely cemented sandstone and shale strata of these formations can rarely be followed with certainty for distances of more than a few hundred feet. And in order to secure trustworthy data it was necessary to find a bed that could be followed without pos- sibility of error and sampled comparably at various points. After considerable search, two beds were found that met the specifications very well. One is a two-foot sandstone that im- mediately underlies a very conspicuous stratum of white volcanic ash. This bed, which occurs about the middle of the Etchegoin group, can be followed about two miles along the strike. The second bed is the so-called “ freshwater bed ” which was taken by Arnold and Anderson as the base of the Tulare formation. It is somewhat less definite and persistent than the foregoing, but can be followed for a much greater distance.

As a sample of the results obtained from the study of these and one or two other beds, Table III. is presented. It shows; in gen- eral, a gratifying degree of similarity in the heavy mineral as- semblages of the various samples. The method used to obtain the percentage figures, which consisted simply in counting at random a hundred grains as seen under the microscope, precludes the possibility of securing entirely accurate results. Especially

18 Cf, quotation from Cayeux, loc. cit.

Coalinga Tertiary Formations. 747

is this true of the minerals that occur in small proportion. When studied by themselves, however, these rare minerals, with the single exception of topaz, were found to be about as uniformly distributed among the different samples as the more abundant minerals. The “ freshwater bed” gave comparable results. An- other bed, which was less uniform than either of those mentioned, and which was therefore difficult to sample uniformly, gave much less promising results. The outcome of the investigation, how- ever, is not unfairly exemplified by Table III.

Table Iii.

SAMPLES TAKEN FROM SANDSTONE UNDER WuitTe, ASH BED; ARRANGED IN ORDER, AS TAKEN, FROM WEST TO East; Two MILES FROM First SAMPLE TO Last.

SP A aes (a RT eRe ERE eae A ee See HIOMMBIENGE 6.6 se. 2:52.60 68 72 74 81 75 80 77 68 71 GIAUCODNANG 5.5.4 i 4 I 3 5 2 2 a --S:41 8 Basaleionb... oi. +... 9 4 Pe Pee 2 2 cull SSOIQHIESS IK 5 5 Soin eee — —. oes — Ais. ELYDETSENENE . 5.5 006 50150 ee ee — — ae po ARR Creista ie aioe escae isee (Moe — — — —s AR AASBINC ag cotsel's 66a ovens te Pei, (Se BS 3 I 4 Sf Ses MEER feos nln Rist 2 1a ws) So oe a a ie r +. 2

In evaluating these results, it must be remembered that the only cases studied were, by necessity, exceptional cases. Only beds that were themselves conspicuously regular and persistent could be sampled, and then only if they were more resistant than the associated strata. In drilling a well through these formations there is no reason to doubt that similar beds would occasionally be found. One should expect, however, to find them interbedded with many other beds less uniform than themselves in heavy min- eral content.

748 R. D. Reed.

The Heavy Minerals Of A Formation.

Between the Miocene and Pliocene formations of the Coalinga district no persistent differences in heavy mineral content have been discovered. As already suggested, however, any sample of the Avenal sandstone of Eocene age can readily be distinguished, by a mere glance at its heavy minerals, from a sample of any of the Miocene or Pliocene formations. There is no reason to doubt that similar differences may be found elsewhere between otherwise similar formations, and that they may often prove valuable in field mapping.

Concluding Remarks On Correlation Of Well Samples.

The preceding discussion has shown that the heavy minerals may throw light on some important phases of the history of the formations in which they occur; it has shown that their distribu- tion in certain California Tertiary formations is such as to render them of probable utility in the making of correlations; it has not directly touched, however, upon the important problem of cor- relating well samples. It may therefore be worth while to list, in conclusion, some of the advantages and disadvantages that these minerals may be conceived to offer for this important task. The disadvantages will be mentioned first.

In the first place, heavy mineral zones are not conspicuous. They cannot be found by a driller, or even by a geologist not specially trained in the methods of sedimentary petrography. Conspicuous markers, such as beds of red or green shale, or beds crowded with peculiar fossils or concretions, would certainly be much better than even the best heavy mineral zones. The latter may be useful, however, in some of the very numerous cases in which the former are entirely lacking.

In the second place, the assemblages of heavy minerals that make a bed or zone distinctive may be repeated even in the same formation. Certain fossils may be limited to beds of a definite age, but individual heavy minerals or groups of heavy minerals rarely or never are so limited. For this reason the best results can be obtained only by studying the heavy minerals of all the

Coalinga Tertiary Formations. 749

strata penetrated in a well. The various zones found in a hole, if compared carefully with those found in another hole, may tell much about the stratigraphic relations of the rocks penetrated in the two holes. Examination of only a few samples from either hole, however, is likely to tell but little.

The third disadvantage of the heavy minerals lies in the fact that zones probably do not at the best transcend the limits of a single basin of deposition. In the making of long distance cor- relations there is no reason to expect the heavy minerals to offer any serious competition to paleontology.

To offset these serious disadvantages, the heavy minerals have a few points in their favor. They are, for example, apparently never absent from a moderate-sized sample of any kind of sedi- mentary rock. Even a teaspoonful of fine clay, or a bit of structureless limestone, will usually yield a surprising collection of heavy minerals. To anyone who has vainly hunted fossils in samples representing hundreds of feet of sediments, this property of the heavy minerals will strongly commend itself.

In the second place, the heavy minerals in a sample are almost always perfectly preserved and therefore identifiable with ease and certainty. Only the class of ferromagnesian heavy minerals, such as the amphiboles and pyroxenes, sometimes furnishes poorly preserved material.

Finally, there is some reason to believe that heavy mineral zones, at least in the California Tertiary formations, are in gen- eral thinner than most fossil zones. Few species of organism can be shown to have come into existence, flourished, and died out during the deposition of only a few feet of sediment. If an organism, a foraminifer for example, seems to be restricted locally to a thin zone, currents rather than evolutionary changes may possibly be the cause. But whenever this is true, the chief superiority of fossils as markers, their restriction to beds of a definite age, is temporarily inoperative. In what particular are such fossil zones superior to heavy mineral zones?

1021 Forest Court, Pato Atto, CAL.

THE PRE-CAMBRIAN COMPLEX AND PYR- RHOTITE BANDS, DUSKY SOUND, NEW ZEALAND.

James Park.

Introduction.

In 1887, William Docherty, an adventurous prospector belong- ing to a type now almost extinct, after many years of fruitless toil and hardship in the lonely fiords of Otago, discovered several mineralized bands of rock on the high country lying between Dusky Sound and Wet Jacket Arm. With the aid of a small Government subsidy he cut tracks through the forest to the grass- lands above the timber line where most of the outcrops occurred, and dug trenches at the most promising places. Acting in accord- ance with the instructions of my old chief, Sir James Hector, F.R.S., I spent a week in December, 1887, in a field examination of Docherty’s discoveries.*

General Geology.

A complex of gneisses, crystalline schists and marbles, and an overlying series of greywackes, phyllites and slaty argillites con- taining Upper Cambrian and Ordovician graptolites at one time occupied the whole of what is now the fiordland of Otago and Southland, comprising the Archzan system of Hector and Hut- ton. In the late Paleozoic these rocks were intruded by a deep- seated dioritic magma which in one phase graded into granite, and in another into norite and gabbro.

As a consequence of uplift and prolonged denudation the plutonic intrusives have become exposed at the surface through- out the greater part of Fiordland thereby breaking up the crystal- line complex into many small, widely-separated blocks. The

1J. Park, “ Geological Reports and Explorations, 1887-88,” pp. 9-15, Welling- ton, 1888.

PRE-CAMBRIAN COMPLEX AND PYRRHOTITE. 751 largest remnant of the gneisses and schists occurs between Pres- ervation Inlet and Dusky Sound.

Until 1921 the diorites, granites, and norites were believed to have invaded only the crystalline complex, and the association was so intimate that they were considered part and parcel of that system. It is now known that they intruded not only the over- lying Upper Cambrian and Ordovician rocks but also the Permo- Carboniferous greywackes and argillites of the Darran Mountains along the northeast border’of the fiord country.

All the great fiords have been formed in the dioritic intrusives, and only in the Dusky Sound area do the crystalline rocks play an important part in the structure of the country.

From the head of that sound to the sea the gneisses and schists dip continuously to the west, that is away from the intrusives, at angles ranging from 45° to25°. They are not folded or plicated. Their thickness is not less than 14,000 feet and may possibly ex- ceed 20,000 feet. .

The less altered Upper Cambrian and Ordovician sediments also dip to the west but generally at higher angles, this arising in part from the disturbance attending local dioritic intrusions, and in part from faulting.

At some of the coastal headlands, strips of the Lower Tertiary coal-measures abut abruptly against the older rocks, being tilted on end along the course of a powerful fault which runs parallel with the northeasterly trend of the coast line.

The eastern boundary of Fiordland is formed by the Waiau trough in which lie lakes Te Anau and Manapouri. Many trans- verse faults radiate towards the west from this depression. And it was along the course of these faults, when the land stood at a higher altitude than at present, that the fiord-like arms of lakes Te Anau and Manapouri stretching far to the west and the great western sounds themselves were formed, for the most part by fluviatile activity. The newly-formed canyons were afterwards deepened and modified in contour by the Pleistocene glaciers that descended from the main chain, and eventually submerged by the negative movement that set in towards the close of that epoch.

752 James Park.

At the entrance of each sound, from Chalky Sound north to Milford Sound, there is a submerged barrier of morainic ma- terial, the presence of which leads to the reflection that before the subsidence began the sounds were occupied by deep freshwater lakes.

Crystalline Rocks.—These consist of gneisses often granitoid, quartzites, beds of marble in places speckled with graphite, quartz- mica-schist frequently garnetiferous, hornblendic and chloritic schists.

The most common gneiss is a typical hornblende-gneiss in which the quartz is often flattened in a direction parallel with the foliation. The dominant feldspars are orthoclase and micro- cline. An acid plagioclase, mainly albite, is always present, and where abundant the rock may be called a quartz-diorite-gneiss. The most common accessory minerals are epidote, chlorite, zoisite, rutile, titanite, magnetite and apatite.

The origin of the gneisses is unknown but the presence of the intercalated marble beds proves that they are in part altered sedi- ments.

The foliation of the schists is parallel with bedding planes of the sediments from which they originated. The chloritic schists may possibly be altered basic effusives. With them occur thin bands of amphibole-quartz-schist. The relative abundance of garnet, epidote and other lime silicates would tend to show that the original sediments were calcareous.

The crystalline complex and plutonic intrusives form the core of the main alpine chain, and are the shield against which the Mesozoic rocks of which the chain is composed were folded. They have been described by Dr. J. M. Bell* and Mr. P. G. Morgan far to the north of the sounds country.

Dioritic Intrusives.—The prevailing diorite is a hornblende- bearing quartz-biotite-diorite, as a rule coarsely granular and typically hypidiomorphic. The feldspars are plagioclase and an- orthoclase. In the quartz occur microlites that may possibly be

2 Bulletin No. 1 (N. S.), N. Z. Geol. Surv., pp. 40-48, 1906. 3 Bulletin No. 6 (N. S.), N. Z. Geol. Surv., pp. 76-95, 1908.

PRE-CAMBRIAN COMPLEX AND PYRRHOTITE. 753 diopside. Apatite and zircon are also present, and titanite be- tween the biotite and hornblende. ,

To the north the diorite grades into a quartz-norite with biotite and may be called a hypersthene-bearing quartz-biotite diorite. To the south the diorites grade into a hypidiomorphic biotite-granite with orthoclase, albite-oligoclase with basic oligo- clase as inclusions, and plagioclase. Albite also occurs as long bands in the orthoclase. Rutile, titanite and magnetite are also present. Quartz is abundant. The biotite apparently developed from hornblende or some other mafic mineral. Dikes of aplite are common, and wide bands of granite with micropegmatitic structure occur in many places.

Mineralized Bands.

On the upland grass-lands between Mount Hodge and Mount Pindar Docherty discovered seven mineralized bands of quartzose rock. These bands lie parallel with the foliation planes of the schists in which they are enclosed and possess the same dip. They are discontinuous. All contain bunches of pyrite; four contain, in addition, a little chalcopyrite; and three, grains of nickeliferous pyrrhotite. In two of the mineralized bands the pyrrhotite is concentrated into a succession of lenses connected by strings of widely scattered bunches of the same ore.

The outcrops occur at altitudes ranging from 3150 feet to 3350 feet above sea-level.

Band No. 1, the lowest of the series, is a quartz-schist 40 feet thick lying between walls of granular feldspathic schist. It con- tains grains and patches of pyrite, and though the least mineral- ized of all the bands, is rendered conspicuous by the presence in it of thin irregular layers of fuchsite and large grains of ouvar- ovite.

Band No. 2 crops out 40 yards to the westward. It is a bed of quartzite the thickness of which is unknown, the outcrop being obscured by peaty accumulations. Patches of pyrite are plentiful in this band, and also numerous tabular crystals of quartz that are probably pseudomorphs after barite.

754 James Park.

Band No. 3 crops out 450 yards to the west of No. 2. Itisa bed of quartzite three feet thick interbedded in biotite-schist. In this quartzose band there occurs a band of pure nickeliferous pyrrhotite four inches thick. Patches of pyrite and a little chal- copyrite are also present accompanied by large well-developed crystals of orthoclase, slates of lepidolite, and nests of amphibole. The pyrrhotite contains 0.56 per cent. of nickel, 0.27 per cent. of copper, and a trace of silver.

Band No. 4 is a bed of micaceous quartzite two feet thick lying 150 feet higher in the sequence than No. 3. It is interbedded with layers of chlorite with which are associated quartz, pyrite, chalcopyrite, magnetite, sphene and rutile. The enclosing rock is a feldspathic schist.

Band No. 5 occurs 40 feet higher in the section. It is a six- inch band of micaceous quartzite containing well-developed crys- tals of epidote, and grains of pyrite, pyrrhotite and chalcopyrite associated with garnets.

Band No. 6 is a quartzose rock four feet thick with abundant epidote and nests of pyrrhotite and chalcopyrite. It is veined with massive garnet rock.

Band No. 7 is a bed of quartzite of unknown thickness lying 400 feet above No. 6. It contains small garnets, and grains of magnetite disseminated throughout the matrix and concentrated in thin irregular layers.

Mount Hodge Pyrrhotite Bed—On the eastern slopes of Mount Hodge a band of nickeliferous pyrrhotite two feet thick occurs in a quartz-mica-schist. It crops out at altitudes of 1,200, 2,240 and 3,150 feet above the sea rising with the enclosing schist to the east at an angle of 25°. With the schist there are associ- ated thin bands of chlorite-schist, quartzite containing a little chalcopyrite, hornblende-schist, tremolite-schist, talc-schist and a gneissoid mica-schist containing large crystals of orthoclase and idocrase. ‘The pyrrhotite contains 0.68 per cent. of nickel.

The relationship of this ore-bearing zone to the seven mineral- ized bands described above is unknown.

In 1887, I called the Mount Hodge mineralized bed a fahlband

Pre-Cambrian Complex And Pyrrhotite. 755

adopting the name suggested by von Cotta for the somewhat similar mineralized crystalline schist bands at Kongsberg in Nor- way.

Quartz V eins ——The mineralized zones of gneiss and schist are crossed by strongly developed quartz veins that strike. north- westerly. The actual point of intersection of these veins and the mineralized bands is nowhere seen being obscured by overburden. It would be interesting to know if these cross-veins cause local enrichment along the contact as happens at Kongsberg where the silver-bearing fahlbands are intersected by similar cross-veins.

Genesis Of Ore.

I saw no igneous dikes penetrating the gneisses and schists in the neighborhood of the mineralized bands, but in the bed of the stream draining the slopes of the range between Mount Hodge and Mount Pindar Docherty found two small boulders of a dia- base-porphyrite. To speculate concerning the part played by the parent dike as a mineralizing agent when there is no evidence of the field relationship between it and the mineralized bands would serve no useful purpose. The concentration of the ores may, for all we know to the contrary, have been coeval with the meta- morphism of the crystalline schists themselves.

Ortaco UNIVERSITY, DuneEDIN, NEw ZEALAND.

Geology And The Location Of Dams In West Texas.’

Leroy T. Patton.

Durinc the winter of 1923-24 the writer was employed by the Board of Water Engineers of the State of Texas to make geo- logical surveys in the vicinity of the proposed dam sites on certain Texas rivers for purpose of ascertaining geological conditions, such as might affect the feasibility of these projects. While this work had for its primary purpose the intensive study of certain particular areas rather than an extensive investigation of any one region, nevertheless, some of the observations made admit of gen- eral application.

The work in question was confined largely to that part of north- west Texas along the Double Mountain Fork of the Brazos River, the Salt Fork of the Brazos River, the Pease River, the Prairie Dog Town Fork of the Red River, and the Canadian River. The present paper does not discuss the conditions in the Canadian River region.

The geological conditions, which affect the construction of dams for flood control and irrigation purposes may be considered under: (1) Those which affect the choice of a location for a dam, and (2) those which affect the dam directly, such as con- ditions which directly endanger the structure itself or reduce the efficiency of the reservoir as a containing basin.

Under the first heading may be considered the geologic condi- tions which control the development of topography, thus creating either favorable or unfavorable conditions for the location of dam sites and for the distribution of water to irrigable lands.

The Texas situation presents two main difficulties to be over- come. It is highly desirable to erect dams on the rivers of the state in order to lessen and control the sudden and destructive

1 Published by permission of the Texas State Board of Water Engineers.

GEOLOGY OF DAMS IN WEST TEXAS. 757 floods to which these rivers are subjected. In order to com- pensate for the large expense necessary in the erection of these dams it is highly desirable that they should be made to serve some other useful purpose such as reservoirs for irrigation pur- poses. To make use of these dams for this purpose, however, it is necessary that the geologic conditions be such that topographic land forms, capable of profitable irrigation, have been developed below the dam site.

Under the second heading are included the important ques- tions of the nature and structure of the geologic formations at the dam site and within the area of the reservoir, in order that it may be determined whether a proposed location is feasible from the standpoint of safety to the structure or the capacity of the reservoir to retain the water without any undue loss by seepage, GiC:

In the discussion of geologic conditions as they affect the ques- tion of location of dams it should be borne in mind that it is probably not possible to find a dam site anywhere, which is ideal in all points. The business of the geologist is to point out diffi- culties. The business of the engineer is to overcome difficulties. A statement of difficulties by the former is by no means to be taken to mean that the latter may not overcome them.

The formations exposed at the surface in the part of the coun- try under consideration in this paper belong to the Permian red- beds. The discussion is confined to the areas of the outcrops of the Double Mountain and Clear Fork formations.

The topography of this part of the state is mainly that of a plain, which is now undergoing dissection. There seems to be evidence that this plain is the remnant of a former erosion plain but it is not within the scope of this paper to discuss this question. This plain lies on both the Clear Fork and the Double Mountain formations.

The Clear Fork formation is composed almost wholly of red shales with a few layers of dolomite and some thin layers of gyp- sum. It weathers very easily and the valleys cut in this forma- tion are in most cases broad and wide with gently sloping sides.

ahitg —

% Deg 16 19845

a

Pa

Leaaat

758 Leroy T. Patton.

Its topography is that of a more or less gently rolling prairie with many large areas of almost level land.

The lithologic nature of the Clear Fork is such that a dam built upon this formation would probably be safe from the stand- point of any danger to the structure or the possibility of seepage. The clay shales of the formation are the type of deposits upon which an earthen dam might be constructed with safety since they are highly impervious themselves and are interbedded with but few thin layers of other material.

On the other hand the nature of the formation is such that as a rule it develops a type of topography unfavorable for the loca- tion of dams. The broad shallow valleys, which are the prevail- ing type developed on this formation, do not offer suitable sites for the construction of dams.

Although the lands situated on the outcrops of the Clear Fork formation are not in general adapted for the location of dams, they do answer the requirements of conditions favorable for the distribution of water for irrigation purposes, since the topogra- phy of these areas is of a character well suited for this purpose, especially those areas which contain large tracts of nearly level land. Considering the relation of these areas to those situated on the Double Mountain formation to the west, where more favorable topography for the location of dam sites occur, this characteristic of the Clear Fork formation is seen to be of im- portance.

The Double Mountain formation lies conformably upon ‘the Clear Fork and outcrops to the west of the latter. The line of contact between the two extends in an almost direct northerly direction in western Jones, eastern Stonewall, western Knox counties, turning to the northeast in Foard, and continuing in a northerly direction in western Wilbarger County.

The topography of the Double Mountain formation is in de- cided contrast to that of the Clear Fork. This is due both to the lithologic character and the structural relations of the forma- tion. The lower part of the Double Mountain formation for 200 feet or more is composed almost wholly of sandstones and con-

Geology Of Dams In West Texas. 759

glomerates. Above this is a succession of gypsum beds, sand- stones and shales. In the eastern part of its outcrop the forma- tion has a dip to the west and northwest. This is especially no- ticeable in the region of Stonewall County. The streams of the region in general cross the country from the west so that they flow agair:st the direction of the dip. The Double Mountain is cliff forming, not only on account of the heavy sandstones and conglomerates at the base of the formation, but on account of the massive gypsum members found higher up in the formation. Because of this, and the fact that the streams are not adjusted to structure but flow against the direction of the dip, the stream valleys west of the contact of the Clear Fork and Double Moun- tain flow through deep, steep-sided, narrow valleys—a type of topography admirably suited for the location of dam sites. This topographic advantage is offset in much of the region, however, on account of the excessive amount of gypsum in the formation. This material, on account of its comparatively high degree of solubility, constitutes more or less of a menace, since solution channels might more readily form in it than in other deposits. Moreover, in some places it is found that underground caverns and caves of considerable extent have developed in it rendering such situations unfit for the location of dams.

The lower one hundred or two hundred feet of the Double Mountain formation, however, is comparatively free from gyp- sum being composed almost entirely of sandstones and conglom- erates. One account of the westward dip of the formation throughout much of its extent this lower portion forms a some- what steep eastward facing escarpment, which stands up above the lower levels of the Clear Fork plain. Streams flowing to the east, therefore, in breaking through this escarpment have formed rather narrow and steep-sided valleys. In such situations favor- able topographic and geologic conditions would seem to be well combined. The valley walls are composed of the sandstones and conglomerates of the lower part of the Double Mountain for- mation, and in some situations also partly of the impervious shales of the Clear Fork. The valley bottoms are formed of the

760 Leroy T. Patton.

Clear Fork shales. The formations offer practically no danger to dams which might be placed in such situations and the topog- raphy of the valleys approaches the type most favorable for the construction of dams.

Unfortunately the westward dip of the Double Mountain for- mation carries its lower part beneath the level of the streams in short distances to the west of where the valleys open out upon the Clear Fork plain so that the opportunities for finding favorable dam and reservoir sites within the area of most favorable geo- logic conditions are confined to short stretches of the valleys. In addition to this, the tendency of valleys to flare at their mouths, even where breaking through an escarpment, reduces the chances of finding favorable dam and reservoir sites within the area of favorable geologic conditions.

It will be recalled that one of the conditions imposed upon these projects was, that the situation should be such that it would allow the easy distribution of the impounded waters to irrigable lands. It would seem that dams located where the valleys open out upon the Clear Fork plain would answer this condition ideally. The Clear Fork plain is for the most part level and has some ex- cellent agricultural land. However, it appears that the Clear Fork plain is probably part of the former erosional surface which cut across both Double Mountain and Clear Fork formation. Elevations taken on the Double Mountain escarpment and upon various parts of the Clear Fork plain show that dams located where the streams break through the Double Mountain escarp- ment would not have sufficient height to allow water to be dis- tributed to certain parts of the Clear Fork plain. This is the situation that would be expected if this plain is a part of an old erosional surface which cuts across both the Double Mountain and Clear Fork. There are, however, considerable areas which have been reduced during the second cycle of erosion to which the above objection does not apply.

As has been already mentioned, the part of the Double Moun- tain formation near the middle of the section, which contains the massive gypsum, although developing a favorable topography,

Geology Of Dams In West Texas. 761

does not furnish good sites on account of the excessive amount of gypsum. If, however, the valleys are followed to the west, the dip of the formation is sufficient, in part of the region, to bring the upper part of the formation into the bottom and sides of the valleys. The upper part of the Double Mountain forma- tion contains much less gypsum than the middle so that some of the danger on account of the presence of the gypsum is avoided, although dams built in such situations would of course be subject to any dangers which might ensue as the result of the presence of the heavy gypsum members underneath the bottoms of the valleys. Such situations are also subject to the disadvantage of the dis- tance to the Clear Fork plain, although other more convenient irrigable lands may be found in some places.

In the northern part of the region under discussion the west- ward dip is less than in the southern and difficulty is experienced in avoiding the heavy gypsum members by seeking locations farther west as outlined above.

In summarizing, then, it may be said that the situations com- bining the most favorable topographic and geologic advantages may be looked for near the Clear-Fork Double Mountain contact; that in certain places situations combining somewhat less favor- able conditions may be sought for where the westward dip of the formations brings the upper part of the Double Mountain for- mation into the bottom and sides of the valleys; and that the least favorable conditions are found where the middle part of the Double Mountain formation occupies the bottom and sides of the valleys.

University Of Texas, Austin, Texas.

Editorial

Microchemical Reactions.

THERE is surely nothing especially new or modern about chemi- cal tests ‘en miniature.” As long ago as 1885 some of us used Boricky’s scheme for determining alkalies in feldspars. Brauns wrote a useful book about microchemistry, and the last edition of Behrens-Kley is complete and exhaustive. Chamot has pub- lished a smaller work on the subject, in English, but it is lacking in some of the reactions for rarer elements which the student of mineralogy often meets. So the method and the technique are there free for anyone to acquire. And yet it seems to me that they have fallen into a sort of “ innocuous desuetude.”” At least so I surmise, for at many institutions of learning little or no use is made of this exceedingly useful instrument, and several friends of the geological, yea even of the mineralogical brotherhood, who have recently honored me with a visit have confessed that they never realized the possibilities of reactions on a glass slide, under the microscope, and have become quite enthusiastic.

Really, it is a fascinating pursuit. Nothing could be more elegant than the determination of copper, cobalt, and zine by thiocyanate of ammonium and mercury, or of copper and lead by the black cubes of triple nitrite. One can put a fraction of a milligram of the material to be tested on the glass slide, dissolve in a drop of nitric acid, evaporate, perform one or two little tricks and, presto the beautiful and characteristic crystals begin to grow at the edge of the drop. Colorimetric reactions are equally char- acteristic in a drop on a glass slide as in a test tube and to start with one needs only a fragment of the size of quarter of a pin head. There is a very good test for vanadium leading to the crystallization of lens-shaped crystals of ammonium vanadate,

Editorial. 763

but a drop of hydrogen peroxide yielding a most characteristic reddish brown color is the safer way.

To be sure there are limitations: It is not easily possible to detect the gold in a low grade pyrite, nor a small amount of silver in galena. Whenever possible silicate should be brought in solu- tion by acids rather than by fusion, though a borax bead may often serve well. Of course, the blowpipe can not be eliminated ; for instance, there is no test for antimony at all comparable to that of the gypsum plate and bismuth flux.

Some things are a little perverse. Suppose one desires to bring out the silver in a natural haloid salt, such as cerargyrite, bromyrite, or iodyrite. It is almost impossible to bring the ma- terial in solution; ammonia should do it, but usually does not. Fortunately there are delicate blowpipe reactions and the chlorine, bromine, and iodine are much better obtained by Plattner’s great method with bismuth sulphide in a narrow tube where they ap- pear as successive sublimates of yellow, red and white bismuth haloids. Zirconium and beryllium are rather troublesome.

Most of these microchemical reactions are so devised that a very characteristic compound is formed which contains but little of the element looked for, like cobalt in mercuri-thiocyanate of ammonium and cobalt. Also in such a manner that other metals present do not interfere. Should they do so there are always methods available for precipitation and decantation on a glass slide. Referring to the cobalt reaction just mentioned, iron is not precipitated but forms a red, obscuring liquid. But after the cobalt has been precipitated the drop can easily be diluted and decanted on the same slide so that the dark blue crystals become visible. Naturally, the tests can not be made fool proof: One must know the state of oxidation and the valency of the solution: pallado and palladic salts do not act alike at all. This, of course, is trite, but is the cause of many mishaps on the part of students.

Next, it is necessary to know the reaction and the crystals, and unavoidably this takes a little time but when once learnt is not easily forgotten. A student in looking for the beautiful yellow brushes of the gold reaction with thallo nitrate by some mistake

764 Editorial.

failed to get them but instead did get some brownish prisms of uncertain parentage whereupon he corrected Behrens-Kley by annotating it “also brownish prisms.’”’ One must be sure.

Still another thing which I want to impress upon those desir- ous of acquiring this gentle art, is not to mix up the parapher- nalia with other instruments, apparatus, specimens or books but to devote one scrupulously clean table to it with glass plate, proper reagent boxes, microburner, etc., and to display a promi- nent sign reading “ Hands off,” above it.

Nowadays we do much work on ores by metallographic meth- ods. (A new word is needed for this: Neither “ Mineragra- phic,” nor “ Chalcographic” will do. The editor should offer a prize.). In such work a frequently recurring problem is to de- termine the chemical composition of small masses discovered on the polished section. Etching tests are good but not always con- clusive. Too often there is not enough available for an ordinary chemical analysis. Here, the microchemical reactions come in particularly conveniently. A minute amount of the doubtful mineral is drilled out with a dentist’s tool, sufficient probably for half a dozen micro reactions. No one who has much to do with examining ores can afford to remain unacquainted with this powerful aid to diagnosis.

Waldemar Lindgren.

Discussion And Informal Communications

Fluorite In Bolivian Tin Mines.

Sir: I have received a letter from Dr. L. J. Spencer, calling my attention to the fact that the occurrence of fluorite in Bolivian tin mines has already been noted in the literature.

In a book entitled the “ Bolivian Andes” by Sir Martin Con- way, London, 1911, no mention is apparently made of the mines at Chacaltaya, which form the subject of my article in Economic GEOLOGY, vol. 19, 1924, p. 223, but in the appendix to the above mentioned book, there is a brief note by Dr. Spencer, calling at- tention to the occurrence of fluorite in specimens from that local- ity, collected by Sir Martin. An article by Dr. Spencer, en- titled “ Notes on Some Bolivian Minerals (Jamesonite, Andrad- ite, Cassiterite, Tourmaline, etc.) ’’ was published in the Min- eralogical Magazine, vol. 14, 1907, pp. 308-344. On p. 337, there is a brief description of identification of fluorite with cas- siterite as occurring at Chacaltaya. Dr. Spencer also states that C. S. Pasley says that fluorite is found with pyrite and tin at Colquiri in the Province of Inquisivi, fifty miles north of Oruru. This article entitled ““The Tin Mines of Bolivia” was published in the Transactions of the Inst. Min. and Met. (Lon- don), 1898, p. 83. Dr. Spencer further mentions that a state- ment of fluorite occurring in Bolivia is made in the Annual Re- port of the Museum Senckenbergianum at Frankfurt am Main, in Germany, the specimen labelled fluorite from ‘‘ Gang Lipez,” Bolivia.

In view of this information I plead guilty, but as none of the references given mention any thing beyond the bare occurrence I think there is good excuse for my communication. I may have

766 Discussion And Informal Communications.

relied too much on the statements of other investigators, like Singewald, Davy, and Hall, to none of whom the occurrence of fluorite in Bolivia appears to have been known.

Also, mineralogists have a habit, somewhat disconcerting to the searcher of literature, of publishing articles on a great num- ber of minerals from some region in such a way that it is almost impossible to find the references by consulting indices and lists of contents. It appears to me that a title should clearly indicate either the locality, or the specific name of the minerals referred to.

Waldemar Lindgren.

Mass. Inst. oF TECHNOLOGY, CAMBRIDGE, Mass.

Spectroscopy Applied To Mineral Determination.

Sir: In the study of polished sections of ore minerals, the de- termination of the minerals present is frequently difficult. Struc- ture and age relations can be solved by a proper interpretation of what is actually seen under the microscope: this is a geological problem. ‘To determine the identity of a mineral which is not readily recognizable at sight is, however, a chemical problem. The well-known tests of Davey and Farnham, Murdoch and others, while quite useful for some varieties, do not give uni- formly consistent results for all species.

Last year the writer’s attention was called to the work of Sir Norman Lockyer, C. P. Butler, de Boisbaudran and de Gramont who had applied spectroscopic methods to determine certain ele- ments in some terrestrial light sources. They used the methods that have been gradually developed since the science of spectro- scopy had its birth in the year 1666, when Newton discovered that rays of different wave-lengths are refracted at different angles. Subsequently the writer has endeavored to investigate whether the elements constituting the minerals could be easily and quickly determined by such methods, in the hope that a knowledge of their constituents would lead to their identity. In

Discussion And Informal Communications. 767

this investigation which is as yet in its experimental stage, en- couragement and advice have been received from Professor F. A. Saunders of the Department of Physics and Professors Graton and Palache of the Geological and Mineralogical Departments of Harvard College.

Theory.—Atomic physics has shown that the atoms of every element when properly excited emit or absorb characteristic radia- tions of definite wave-length. If a photograph be taken of these radiations, it is found that waves of definite length (seen as lines on the plate) can be associated with definite elements. The methods of excitation which have been employed are by the arc and spark in air.

Methods.—A quartz spectroscope made by Adam Hilgar of London was used. Photographs of the lines of the elements ranging in wave-length from 2,100 to 5,200 Angstrom Units can be taken with this instrument. This range is toward the violet end of the spectrum and partly in the ultra-violet. The visible spectrum extends from 3,900 to 7,600 A. U.

A grain of the mineral is placed in a crater-shaped depression in the end of a graphite electrode, which in the case of the arc spectrum is the positive. The arc is made by bringing down the negative graphite electrode into contact with the positive, then withdrawing it a little, so as to obtain a greater length of arc. The image of the arc is focussed by means of a quartz lens onto the slit of the spectroscope. The rays pass through the quartz prism and are received on the photographic plate. The time of exposure varies from one to three seconds, depending on the ma- terial. When spark excitation is used the two electrodes are set about one centimeter apart, the mineral being placed on the lower one. For each specimen examined the ends of the electrodes are freshly turned in a lathe to eliminate any contamination from elements previously tested. The first photograph taken on each plate is a “ blank” of the electrodes alone, since lines due to the electrodes are always present and form a background upon which is superimposed the characteristic spectrum of the element whose identity is desired.

768 Discussion And Informal Communications.

Preliminary Results—Are and spark photographs have been taken of each of the principal mineral-forming elements and the characteristic lines for each element designated by key dots in ink, placed just at the top of the line on the emulsion side of the plate. When the picture of an unknown is taken, the position of the main lines revealed is roughly noted by use of a finding scale, and then the unknown plate is superimposed on the knowns and the various elements thus determined.

The methods above described have been applied to a number of minerals, both known and unknown, with promising results. For example, tennantite and tetrahedrite which by the methods in use are so difficult to distinguish can thus be separated easily. The constituents of some of the unknown minerals which occur associated with bornite in certain copper ores, and which have been seen only under the microscope, have been determined. The small mineral grains were wedged out by means of a chisel- pointed needle and gathered up in vaseline which was smeared onto the electrodes.

If results in the future justify, a fuller report with character- istic spectra photographs will be published.

G. VIBERT DouGLas.

The Permeability Of Rocks.

Sir: I have read the paper which Mr. Th. Dahlblom presented on the above subject on pp. 389-392 of the present volume of Economic GreoLtocy. Mr. Dahlblom argues for the absence or very small amount of water in.rocks at depths of only a few hun- dred feet. He speaks chiefly from experience in mining. His only quotation in reference to the facts discovered in the drilling of wells, or bore-holes, is from a paper published by Mr. R. Campbell in 1914. I would suggest that Mr. Dahlblom might do well to look over the very abundant literature written on oil production since 1914. Water, sometimes in great quantities, is frequently encountered in drilling wells for oil, and often at depths greater than 2,500 and 3,000 feet. This is a field of in-

Discussion And Informal Communications. 769

formation which certainly ought to receive careful consideration and which should be compared with the data obtained in mining janice

before drawing conclusions as to the permeability of rocks. a

’g Freperic H. Lanee. f/,

Sun O1 Co., Da.ias, TEXAS.

The Identification Of Manganese Minerals.

Sir: The determinative methods for the identification of man- ganese minerals occurring in polished sections have been recently described in Economic GroLoey in‘an excellent article by G. A. Thiel.* The methods described lack completeness to a consider- able extent—without reference to the application of petrographic methods to the study of crushed material. Optical data obtained from finely crushed material, found to transmit light, is more re- liable than the microchemical data ordinarily obtained from study of polished sections. A refractive index liquid of about 1.74 is available, or should be, in most laboratories. The study of crushed material immersed in a liquid of this index has shown that only a few minerals listed by Larsen are apt to be confused.

The following distinctions will serve to distinguish between the minerals which are found to possess certain characteristics in common :

Hausmannite may be confused with hematite as the slight pleochroism sometimes attributed to hematite is of little diagnos- tic value in the distinction from non-pleochroic hausmannite. Andersen made the following observations on micaceous hema- tite, arriving at the conclusion that, “In spite of careful observa- tions, no distinct change in color or tint could be seen in any of

1 Published by consent of the Director of the U. S. Bureau of Mines.

2“The Manganese Minerals: Their Identification and Paragenesis,’ Econ. Geot., vol. 19, No. 2, March, 1924.

8“ The Microscopic Determination of the Non-opaque Minerals,” U. S. G. S. Bull. 679, 1921.

4 Olaf Andersen, “ On Aventurine Feldspar,” Am. Jour. Sci., vol. 40, Oct., 1915, P. 375-

770 Discussion And Informal Communications.

the grains examined. We therefore conclude that the hematite has little or no pleochroism.”

Absorption Color. . Thickness. PASTECIY IODAGUCs ccc io cicgssicioee oho 5s 66m 2 '8 6 5ie 0.0l mm. Very dark blood red, almost opaque 0.003 mm. ADS Pi POR TOU s 5.his oc ce visio eee elas sisisis ws dle ns ata 0.001 mm.

The fact that hematite transmits light only in very finely powdered form or in the case of specularite, in extremely thin plates, serves as a distinction from hausmannite which transmits light in relatively thick crushed fragments.

Braunite may be readily distinguished from hausmannite from the fact that it is opaque in fine powder.

Chalcophanite possesses striking pleochroism but it is not ordi- narily observed, as even finely crushed fragments tend to lie on the perfect basal cleavage in which position the pleochroism is not visible. The pleochroism may be observed when the crushed material is examined with the aid of a Universal stage rotated on the vertical axis.

Columbite and tantalite, which resemble manganese minerals somewhat when viewed in polished section, are stated by Thiel to be indistinguishable. In crushed material, without resort to ex- act refractive index determinations which alone would be suffi- cient to differentiate between the two, columbite remains nearly opaque to deep red while tantalite shows pleochroism from nearly colorless to deep red-brown.

Among the remaining minerals described by Thiel the follow- ing will permit more or less optical data to be obtained by ex- amination in powdered form; alabandite, franklinite, limonite, manganite, huebnerite, manganosite, and wolframite.

Ernest E. FarrBANKS. Reno, NEvapa.

Reviews

The Iron Ores and Iron Industry of China, Part I. By F. R. Tecencren. Mem. Geol. Surv. China, Ser. 4, No. 2, Oct. 1921. Accompanied by an atlas of 39 maps. English text 180 pages. 16 plates; Chinese text 120 pages. Peking, Geological Survey of China, Ministry of Agricul- ture and Commerce, 1921-1923. Part II., December, 1923, pp. 181- 457, pl. XVII-XXV.; Append. “Supplementary notes on the Iron Ores of Shansi,” by C. C. Wang, List of Literature and Geographical Index, pl. I-V.; Chinese text, pp. 120-314. Price $16 Chinese.

This memoir constitutes the first authoritative account of Chinese iron resources given to the public. Sketchy descriptions of particular deposits have been published by various foreign and Chinese geologists, and gen- eral statements regarding the resources of the country as a whole have been made—many of them on inadequate data—but up to now no ac- count of the field even measurably complete has been available to students and the public. Part 1 includes descriptions of the principal known deposits of Chihli, Manchuria, Shantung, Shansi, and Honan. Similar descriptions of the deposits of other provinces, especially those along the Yangtze, are printed in part 2, which also includes a series of papers on the iron industry of China and of the Circum-Pacific countries. The atlas includes sections and maps of the principal deposits.

It may be said at once that the report is strictly modern in form and content and is an excellent example of what may be accomplished even with limited funds and when interrupted by revolution and civil war, if only the spirit and knowledge be present. The immediate author is F. R. Tegengren, formerly of the Geological Survey of Sweden and the work was done under the guidance of Dr. J. R. Andersson, late director of that Survey and sometime advisor on mining matters to the Chinese govern- ment. These men, with V. K. Ting, W. H. Wong, and the whole group of brilliant young Chinese geologists at Peking, have brought to the study experience, industry, and knowledge that warrant confidence in the results.

In general, the survey of the iron ore deposits of China has determined that the earlier ideas, founded on von Richtofen’s work, of large, almost unlimited resources, must be given up. There is no reason to believe that China will become one of the world’s great centers of iron ore production such as the Lake Superior, Lorraine, or Brazilian regions. It is neces- sary, however, to guard against going to too great extreme in the other

772 Reviews.

direction. The survey equally demonstrates that China contains impor- tant bodies of iron ore of varied quality and fairly wide distribution; de- posits which, under a wise development plan, are ample to her needs for a long period. ‘

The author distinguishes on geological grounds, seven types of iron ore deposits but of these four may be set aside as probably of no especial future importance. These are (1) iron sands washed from disintegrated rocks by streams; (2) gossan deposits; (3) nodular and mammillary masses of hematite, limonite, and spherosiderite in sedimentary rocks (Shansi type); (4) metasomatic hematite beds in metamorphosed Car- boniferous (?) sand stone strata (Ping-Hsiang type). The Shansi type was the main reliance of the old iron industry of China, but as W. H. Shockley pointed out some years ago bodies of ore satisfactory as a source of supply of the small primitive furnaces of the country afford no support at all for modern plants. The Ping-Hsiang type is as yet inter- esting mainly to students of the genesis of iron ores since it shows de- velopment from small particles similar in appearance and many particu- lars to the “ greenalite” particles to which C. K. Leith has appealed in his studies of Lake Superior ores. It is possible, though not probable seemingly, that considerable workable bodies of ore of this type may still be found.

The important iron ore bodies of China belong to three types designated by Dr. Tegengren as (1) Archean ores; (2) Pre-Cambrian bedded hema- tite ores (Hsuan-Lung type); (3) contact metamorphic type. Of these the first two are found mainly in the northern provinces and are described in this volume. The third is developed mainly in the Yangtze valley and remains to be described.

“The Archean ores,” to quote, are “probably of sedimentary origin, forming part of the basal complex of crystalline schists with granitic in- trusions, which is exposed in larger and smaller areas over a vast terri- tory in northeastern Chihli and southern Manchuria. The ore, distinctly quartz-banded crystalline hematite and magnetite, occurs as extensive layers occupying a definite stratigraphic horizon between mica schists, and quartzite. As a rule the ore is poor and extremely siliceous, contain- ing 30 per cent. of iron and above 50 per cent. of silica, but also beds of high grade, although somewhat sulphurous, ore are met at some places. A great number of such deposits, some of them of considerable size, are encountered within the territory just mentioned.”

From the point of view of development these ores have the advantage of nearness to coking coal and existing railways and no great distance from the sea. They have the disadvantage that the known bodies of size are so lean as to require beneficiation before going to the furnace. The ex- isting blast furnaces, built with the expectation of being able to supply

REVIEWS. 773 them with raw ore from richer beds, have proved commercially disap- pointing since the bodies of rich ore so far opened prove on development inadequate. Preliminary studies made by Japanese, Chinese, and Ameri- can geologists all give hope that systematic exploration will result in dis- covery of considerable bodies of workable ore but any large iron industry based on the ores of this type will necessarily face the problem of bene- ficiation at an early stage.

The Hsuan-Lung type is in many regards the most interesting in China. To put it briefly for American geologists, the ores are pre-Cambrian oolites of the “ Clinton” type except that they are in quartzites rather than limestones and so are siliceous rather than calcareous

a very im- portant difference to the furnace man. The beds are of good workable thickness, well situated, and bodies of 50,c00,000 tons and more content running 48-56 per cent. metallic iron are‘known. A railroad connection has been made and some of the ore has been smelted. It was this ore that was proposed to be used in the furnace erected near Peking. Any in- dustry founded on these deposits is handicapped by distance from coking

coal, from any good seaport, and situation “off center” as regards con-

sumption. Nonetheless the Hsuan-Lung deposits constitute not only a most interesting geological type but a real, though perhaps future, asset of the nation.

The contact metamorphic deposits have yielded and are yielding the larger part of the iron ore entering into the modern iron industry of China. As Doctor Tegengren says:

“This group is by far the most important one, including several of the largest deposits known in China. The ore deposits, varying in size from minute occurrences of merely scientific interest, to large bodies, contain- ing millions of tons, appear at, or near, the contact between laccolithic masses of grano-diorite and preéxisting sedimentary rocks of both cal- careous and siliceous composition. Sometimes they seem closely to fol- low the contact line—either in the roof or along the periphery of the igneous body. Sometimes they form vein-like bodies in the intruded rock series, occasionally, again, they are enclosed in the igneous rock. In the first case mentioned they often exhibit the typical characteristics of con- tact deposits, the ore being associated with contact-minerals such as garnet and epidote, but often, and especially when they appear as veins in the sedimentary rocks, the only gangue matter is quartz, which can distinctly be seen to fill up the interstices and small cavities of the often very porous and drusy ore substance. Sometimes these cavities have not even been filled at all. This porous structure of the ore and the occurrence of lamellar quartz indicate that the ore was often formed comparatively near to the surface, and at a temperature too low for the formation of the common gangue minerals by interaction with the intruded rock. More- over, the ores belong to a stage distinctly posterior to the consolidation of the grano-diorite, since corroded fragments of the latter are frequently seen to be cemented by the ore substance. Occasionally the ore seems to

774 Reviews.

have replaced also minor bodies of gangue minerals at the contact between the diorite and the sedimentary rock, which had been previously formed, probably by direct interaction between the cooling magma and the sub- stances of the preéxisting rock. Thus, for instance, large cosi-tetrahedra of magnetite are found, bearing every evidence of being pseudomorphic after garnet. Frequently the diorite near the contact with the ore body has been strongly acted upon by volcanic emanations, which have trans- formed it into a kaolin-like mass. From the facts stated above it seems justified to conclude that the ores were chiefly metasomatically deposited from aqueous solutions during a period following the consolidation of at least the marginal parts of the dioritic intrusions.

“The ores consist of hematite and magnetite, the former mineral as a rule predominating. ‘The hematite is partly of a very finely granular or dense structure, but micaceous specularite is also not uncommon, espe- cially as druses in cavities. The magnetite is mostly met with where the ore bodies come into immediate contact with the diorite, but also seems largely to occur in intimate intermixture with the hematite. Hydrated iron minerals, such’as limonite, are encountered in the surficial portions of the deposits. As already stated, quartz makes up the bulk of the as- sociated gangue matter; besides several of the deposits are also mixed up with garnet and epidote. In some cases idiomorphic feldspar is met with in considerable amount. Sulphide minerals such as pyrites, chalcopyrites, and bornite also frequently accompany the ore, occasionally in such a proportion that the commercial value of the ore is considerably lessened. At one place (Ta-Yeh), according to the experience gained hitherto, the amount of sulphides increases towards the depth.

“ Occurrences of this type are widely distributed in Eastern and Central China and are encountered as far North as Manchuria and as far South as Canton. Deposits of economic value are found in Shantung and Honan, but the greatest number of ore bodies, some of very considerable size, seems to belong to a belt along the Lower Yangtse valley in the pro- vinces of Kiangsu Anhui, Kiangsi, and Hupei. This fact is, indeed, so conspicuous that one can hardly escape the idea, strange though it sounds, of some genetic connection between the distribution of the post-Car- boniferous laccoliths of grano-diorite and the present course of the Yangtse river. The ores are somewhat inhomogeneous, but the bulk is high grade, ranging about 60 per cent. in iron, with an intermediate per- centage of phosphorus and a varying but as a rule not objectionable con- tent of sulphur. The ores of this type seem to be closely related to those of Korea and Japan, as well as the deposits along the Pacific Slope of the Americas.”

The individual deposits along the Yangtze are described in the second part of the report. It remains to recall that the Ta-Yeh ore bodies re- ferred to are those that have fed the Hanyehping furnaces at Hankow and now supply the new stacks at Ta-Yeh. The ore that the Kai Lan Mining Administration is to smelt at its furnace near Ching Wang Tao is of the same type being mined from deposits nearer the mouth of the Yangtze and brought to the furnace as back freight in boats taking coal to the Yangtze valley.

In general it may be pointed out that in China as elsewhere the location

een aed, sub- dra ohic ody ans- ems ited f at

as a r or spe- the ems ated ions - as- 1 up with ‘ites, ha ned. the

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‘cond S re- nkow Lan Tao f£ the - coal

ation

Reviews. 775

and support of blast furnaces is determined more by the presence of cok- ing coal and market for products than the supply of ore, and that enough ore of suitable grade is present to support more furnaces than other con- ditions warrant even though it is true that the early exaggerated ideas of China’s great wealth of iron ore must be abandoned. Doctor Tegengren estimates the total actual iron ore reserves of the country at 396,000,000 tons containing 166,000,000 tons of metallic iron. The additional poten- tial reserves he places at 555,700,000 tons containing 202,200,000 tons of metallic iron. He finds on review that the countries bordering the Pacific are, as compared with those about the Atlantic, deficient in iron ores and even more lacking in coking coal and of localities in which the combina- tion of elements favors the growth of a large steel industry. His final summary, with which the reviewer is entirely in agreement, is as follows:

“Upon the whole, therefore, the conclusion seems unavoidable that—as long as the ordinary blast-furnace process remains the foundation stone of every large scale iron manufacture—none of the countries bordering the Pacific has been in any eminent degree endowed by nature with the prerequisites for becoming an iron producer of high rank. On the other hand, iron production on a moderate scale may prove feasible and profit-

able in a great many places.”

Such production on a moderate scale will be entirely adequate to the

needs of many of the Pacific countries for an indefinite period and will

permit some exportation as from India and Australia, though the great

centers of the world’s production are not likely to be shifted to the Pacific. H. Foster Barn.

The Evolution and Distribution of Fishes. By J. M. Macrartane. The

Macmillan Company, 1923, 564 pages, 72 text figures.

Fishes, The Source of Petroleum. By J. M. Macrartane. The Mac- millan Company, 1923, 451 pages, 50 text figures.

Starting with the belief that life originated in fresh waters, these com- panion volumes by Dr. Macfarlane, Emeritus Professor of Botany at Pittsburgh, have led far afield to views quite heterodox. The first de- velops the thesis that most of the fishes of the geologic past have been confined to fresh waters. It is argued not only that they originated in inland waters but also that none save a few Mississippian sharks invaded the sea before Jurassic time. The sequel undertakes “to demonstrate conclusively that practically the entire source of petroleum has been cer- tain disintegrated and decomposed constituents of fishes.” If the reader is surprised at the outset by these extreme views, he will be no less dis- mayed by the geologic and biologic doctrines invoked in their support.

In the author’s mind volcanoes and fishes play a complementary réle in the origin of petroleum for the burial and conservation of the fish is at-

776 Reviews.

tributed to falls of volcanic dust. The past geologic agencies for de- struction of fish-life, are said to be “chiefly the various volcanic and seismic disturbances that have periodically caused local or even cosmic changes of a fundamental nature.” After reviewing the activity of familiar volcanoes as Vesuvius and Krakatoa he concludes that, “it is in this way that the writer has explained the formation of some fish beds, and even more of fine argillaceous, calcareous or shaly sandstone strata in which myriads of entire fishes are encased.” Oil shales are interpreted as such volcanic materials which have absorbed the oily products of the entombed fish, and then, as if to satisfy the skeptical petrologist, it is added that—“ As to the nature of the volcanic dust this may vary greatly. . . . For its nature and composition evidently depends on the rocks which were upheaved in the volcanic cone or cones, which were then churned and pulverized in the cone-cavity” (italics the reviewer’s). This geo- logical explanation paves the way for the conclusion, later-on, that the “bone bed” of the Onondagan, regarded by geologists as a marine lime- stone, is in reality a fresh-water deposit of volcanic dust.

In successive chapters of the first volume, petroleum deposits of system after system are reviewed with an attempt to correlate each with the pale- ontological evidence of the fishes that gave rise to the oil. For lack of space a single example must illustrate the methods here employed and we may choose the first case considered, that of the Middle Ordovician Tren- ton oils. As the only accepted fish remains known from that remote period are limited to rare fragments of dermal armor found in only three localities in the Rocky Mountain region, the reader would hardly be im- pressed with the “constant and necessary ” association of fish and petro- leum in the Indiana-Ohio fields. The author, however, points to the min- ute denticles known as conodonts, which are common in certain early Paleozoic black shales, and are, as he interprets, the teeth of primitive Cyclostomatous fishes. Although this interpretation is not new, the cono- donts are still regarded by most biologists as an enigma. A recent mono- graph on the Genessee conodonts characterizes them as “teeth of some unknown family of animals,” and after reviewing the history of opinion regarding them quotes from Woodward that “ Their histological structure is so different from that of any teeth known that their affinities are quite indeterminable. They may even be the teeth of unknown nudibranchs or annelids or the hooks of Cephalods and can thus be dismissed as frag- ments too inconclusive for consideration here” (as the teeth of verte- brates). Not so the present author who asserts “Now while varied opinions have been expressed regarding these, the writer would wholly accept the conclusions of the two last-named authors [Newberry and Hinde] that they are teeth of Cyclostomes.” He seems not to have ob-

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Reviews. 777

served that Newberry in his later works abandoned this idea and in 18992 wrote that “Probably ne one now believes that they are the teeth of fishes.” Whether or not they are fish teeth—and they may be—is less fs significant here than the treatment accorded them, for where specialists in this field have failed to reach a decision this writer takes a bold stand and uses it as a firm foundation for his “ complete demonstration.” At- tacked in this spirit all the evidence seems to fit.

With fishes in mind as the single source for petroleum, the author seems to overlook the fact that fishes ultimately feed on other organisms. As the food ultimately consumed by any individual vastly exceeds its own bulk the reader will probably reflect that fishes after all form but a small part of the life of the hydrosphere, and that in the large they are far from having a ‘monopoly on oils.

Nor, in his zeal, does the author consider the deposits of reeking black muds, rich in organic matter, now forming. Danzig Bay, for example, has some 615 square miles of its floor covered with black mud which Bishof? finds to be almost 23 per cent. organic. Kramer and Spilker® reported a similar mud, flooring the Gulf of Stettin, to contain 3 per cent. by weight of organic hydrocarbons. Nevertheless, this material is quietly accumulating at the present time and fishes, so far as reported, do not play an important role. It is needless to say that “ volcanic and seismic” disturbances are not involved in the storing up of these reservoirs of organic fats and oils. Geologists are inclined, however, to look upon them as oil shales in the making.

In the second volume dealing with the origin and distribution of fishes the extensive compilation from the literature is tempered by the same mental attitude noted above and interwoven with the same sort of geo- logic doctrine. To account for the Oligocene fish-bearing limestone of Oeningen, the author explains, “that huge thicknesses of limestone strata were on every side and had to be broken through, caught up periodically in the volcanic vents, and ground to powder there before being extruded as a fine, almost impalpable, powder, which alike in air, when rain-ex- posed, or under water, would speedily set into the hard thin lime lamellae described.”

The well-known lithographic limestones of Solenhofen are given an equally dramatic origin. These wonderful fossil beds and their organic remains are the subject of a splendid monograph by Walther, who inter- prets the fossil beds as the fine silty filling of coral atolls that lay a few miles off shore in a shallow Jurassic sea. Quite disregarding the opinion of Walther, as of all other geologists who have visited Solenhofen, Dr.

1“ Paleozoic Fishes of North America,” U. S. G. S. Mon. 16, p. 14.

2 Lehrbuch der Chem. u. Phys. Geol.

3 Ber. Deutsch Chem. Ges., vol. 32, 1900, p. 2940 and vol. 35, 1902, p. 1212.

778 Reviews.

Macfarlane informs us that it “represents a huge mass of coral rock- deposit that was caught up by a volcano or volcanoes, ground up in its vent during days, or even weeks of eruptions, crystallized and then shot out over hundreds of miles of country.” His conclusion that 110 of the species of fish here associated with corals, sponges, and echinoderms, are of iresh waters, will probably be accepted by geologists in the same spirit as his preceding conclusion on the origin of the sediments in which they lie.

In some of the later chapters the writer makes use of the supposed fresh-water fishes in the determination of some striking paleogeography which leads him to the extreme conclusion that Brazil and Africa were connected by a wide Gondwana land bridge during Cretaceous and Eocene times which probably broke up during “ Oligo-Miocene” time. The reader may think it remarkable that this fish story of broad land connections at so late a date finds no support in the distribution of abun- dant land mammals and land plants.

C. O. DuNnBaR.

Scientific Notes And News

J. E. Spurr of New York delivered three lectures on Ore Deposits at the University of Toronto, under the auspices of the Department of Geology of the University. Invitations were extended to the members of the Toronto Branch of the Canadian Institute of Mining and Metal- lurgy to attend the evening lecture on “Ore Magmas.”

Alired Wandke is now manager of the Guanajuato Consolidated Min- ing and Milling Company, at Guanajuato, Mexico.

W. W. Rubey, of the U. S. Geological Survey, has completed his field work in Wyoming and has returned to Washington.

E. H. Reynolds, of the University of Bristol, England, was a recent visitor to New Haven.

Philip S. Hoyt has been appointed Oil and Gas Inspector of the State of Wyoming.

F. J. Katz, of the U. S. Geological Survey, has been in Pennsylvania, New York, Ohio, Wisconsin, and Iilinois on work for the division of mineral resources.

Frank W. DeWolf is chief geologist of the Boyd Oil Company, Dal- las, Texas.

A. C. Bevan, of the University of Illinois, is now preparing a report on the geology of the Oregon quadrangle, Illinois, for the State Survey.

B. L. Johnson, of the U. S. Geological Survey, has been. examining a proposed cement-manufacturing area near Rockland, Maine.

Gail Moulton has resigned from the University of South Dakota and now holds a full-time appointment on the staff of the Illinois Geological Survey.

T. W. Edgeworth David, professor of geology in the University of Sydney, Australia, was recently chosen one of the correspondents of the Geological Society of America.

J. F. Wright, of the Canadian Geological Survey, has returned to Ottawa from his investigation of the gold and copper area northeast of Winnipeg.

Fred B. Ely has returned from a two years’ geological investigation of petroleum deposits in North Africa, Egypt, Arabia, and the East Indies.

Edwin T. Hodge, professor of economic geology, University of Ore- gon, made a study during the summer of the Cascade Mts. in the vicinity

780 Scientific Notes And News.

of the McKenzie Pass and the Oak Ridge Pass with reference to water supply and power for towns of the Willamette Valley.

Alfred W. G. Wilson, of the Canadian Department of Mines, has re- turned to Canada from Egland, where he was engaged in the dissemina- tion of information regarding Canadian mining.

G. F. Loughlin, of the U. S. Geological Survey, is in Colorado making a survey of the deeper workings in the Cripple Creek and Leadville min- ing districts.

A. W. Stickney is making an examination of the Benguet Consolidated mine in the Philippine Islands.

E. M. Spieker has been granted a leave of absence from the U. S. Geological Survey to give a course in geology at Ohio State University.

Arthur Weigall, mining engineer, has accepted the position of man- ager of the Chosen property in Korea.

U. R. Laves is now supervising diamond core-drilling for the Morton Salt Company in central New York. He will shortly return to his Chicago office.

L. G. Weeks, who recently returned to this country after four years of investigations for the Whitehall Petroleum Corporation, London, has left for South America in the interests of the Standard Oil Company of New Jersey. His address is Room 322, 26 Broadway, New York City.

W. H. Weed has completed an examination of the Rouyn gold mines property for the Weed-Sturgis Syndicate of New York.

R. L. Chase, mining and geological engineer, of Denver, is engaged in mine examination work in Chihuahua, Mexico.

W. H. Blackburn, formerly general superintendent and consulting engineer for the Tonopah Mining Company of Nevada, has opened offices in San Francisco as consulting engineer.

W. Pellew-Harvey is making an examination of the Eileen Alannah mine in South Africa.

Louis W. Huber, a graduate of Illinois University, and Harold J. Sloman, a graduate of Lehigh, have been appointed instructors in the Department of Metallurgical and Mining Engineering at Carnegie In- stitute of Technology in Pittsburgh for the current year.

The Illinois Geological Survey has recently undertaken two new lines of investigations in the interest of their petroleum studies: the chemical character of the oil field waters of Illinois, and microscopic and sedimentation studies of the Chester series. The former problem is being undertaken by Gail F. Moulton, and the latter by J. E. Lamar, who has made a fairly extensive field study of the Chester series and col- lected systematically about 2,000 specimens.

The Pacific Society of Petroleum Geologists was organized during the

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Scientific Notes And News.

first annual convention of California geologists. S. H. Gester, geologist of the Standard Oil Company of California, was elected chairman, and R. R. Morse, professor of geology at the University of California, was/,.

named as secretary. bes : 2 Eugene Stebinger is with the Sociedad Anonina Argentina, Avenida DEC i6 i324

de Mayo 560, Buenos Aires, Argentina. % 2, A new report on the oil possibilities of the Decatur area, by D. M. ol

Collingwood, has just been issued by the Illinois Geological Survey. Oil fae has been found in the Decatur area, but it remains to be seen if it occurs

in sufficient quantities to be commercial. The new bulletin contains

discussions of the general geology of the area and possible oil horizons,

a structure map of the area, and recommendations regarding future

prospecting.

The thirty-seventh annual meeting of the Geological Society of Amer- ica will be held December 29-31, 1924, at Ithaca, New York, by invitation of Cornell University. The address of the retiring president, Waldemar Lindgren will be delivered Monday evening, December 29, followed by the annual smoker. The regular annual dinner of the Society will be held Tuesday evening.

H. Foster Bain, Director of the Bureau of Mines, is in Argentine mak- ing a study of the possibilities of developing an iron and steel industry in that country, at the request of the Argentine Government. He is as- sisted by C. E. Williams and E. B. Swanson. During Mr. Bain’s absence Dorsey A. Lyon will be acting director of the Bureau of Mines.

Oscar H. Hershey recently returned from a mine examination trip to Sinaloa, Mexico.

R. A. F. Penrose, Jr., has been elected a director of the Kennecott Copper Co., taking the place of Samuel J. Clark, who has resigned.

Charles Camsell, Canadian Deputy Minister of Mines, recently visited British Columbia.

Henry W. Turner is examining property in the State of Nayarit, Mexico.

Sir Archibald Geikie, eminent British geologist, died at his home in England, November 10, at the age of eighty-nine years. He had at- tained many of the highest honors of his profession, including the pres- idency of the Royal Society, the Geological Society of London, and the directorship of the Geological Survey of the United Kingdom. He was the author of numerous scientific books and papers. On a visit to the United States in 1897 he gave a series of lectures at Johns Hopkins University.

Alfred H. Brooks, Chief Alaskan Geologist of the U. S. Geological Survey, died suddenly on November 22 at Emergency Hospital, Wash- ! ington, D. C. i

Index To Volume Xix.

[Nore.—In this index the titles of principal papers and the headings of departments, as Discussion, are in italics.]

Adams, F. D., on origin of Sudbury deposits, 199; on resistance of py- rite to deformation, 444

Adams, F. D., and Barlow, A. E., on amphibolites of the Haliburton- Bancroft area, 713

Adams, G. I., on gypsum, 260, 273

Adams, L. H., and Williamson, E. D., on porosity of rocks, 390

Adhesion, action of, 42

Adirondack magnetites, sedimentary phases, 288

Adularia, 380

Ajo, samples of capping, 252

Akaoka, J., on ores of the Hitachi mines, Japan, 438

Alabandite, 115

Alaskan nickel minerals (Budding- ton), 521

Alaskite, 701

Albitite, 71

Alkaline carbonate waters, San Joa- quin Valley, 625

Allanite, large crystals, 707

Alien, E. T., Crenshaw, J. L., and Johnston, J., on mineral sulphides of iron, 472

Alling, H. L., on mineralography of the feldspars, 719 i

Almaden mercury ores and their con- nection with igneous rocks (Van der Veen), 146

Alteration in Sudbury nickel erup- tive, 178; in veins of Grass Valley district, 608

Analyses—braunite, 110; Coastal Plain, California, ground waters, 630; copper ore, Beatson mine, Alaska, 349; Decorah and Galena formations, samples of, 74; dia- base, 148; dike in lower Great Eastern adit, 310; galena, 543, 544; ground water scum, Tintic district, 69; Hausmannite, 111; hydromag- nesite, 415; manganese minerals mixtures, I2I1; manganite, 110; magnesite, 424, 427; California, 419; Eubea, Greece, 418; Kern County, 416; nickel minerals, 528;

nickel sulphides, 317; pentlandite, Yakcbi Island, Alaska, 523; petro- leum ash, 552; psilomelane, 111; pyrolusite, 109; siderite, 656; sul- phate waters, San Joaquin Valley, 624; tailings from Minnesota pot- ash shales, 80; titaniferous mag- netites, 296; Transvaal silver-lead ore, 657; waters of Californian oil field, 629

Andersen, Olaf, on micaceous hema- tite, 769

Andrews, E. C., Prospecting for pe- troleum in Australia, 157-168

Anglesite, 660

Angular inclusions and replacement deposits (Bateman), 504

Angular inclusions, formation, 509

Apatite, 223

Apparatus for measuring capillary force, 39; for X-ray analysis, 7

Apparatus for the measurement of temperatures in deep wells by means of maximum thermometers (Van Orstrand), 229

Argenteuil County, Quebec, magne- site deposits, 423

Arizona asbestos deposits, 386

Arnold, Ralph, and Anderson, Rob- ert, on the Coalinga district, 731

Arsenopyrite, diffraction pattern, 30

Asbestos deposits, Arizona, 386

Ashland, Oregon, oil shales, 463

Astoria area, Oregon, 460

Atlin, British Columbia, magnesite deposit, 415

Atwood, W. W., on enrichment due to climatic chanves. 667

Austin, M. M., and Parr, S. W., on potash shales in Illinois, 75

Australia, geologic structure, 165

Australia, Prospecting for petroleum in (Andrews), 157

Avenal period, 731

Avenal sandstone, 737

Bagg, R. M., on pyrrhotite in Wis- consin, 469

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Index To Volume Xix. 783

Bailey, G. E., on map of Etta lode,

Bailey, L. W., and Matthews, G. F., on New Brunswick magnesite, 420

Bain, G. W., Types of magnesite de- posits and their origin, 412-433; on Argenteuil magnesite deposits,

Bain, H. F., review by, 771

Baker, H. A., on elutriation, 324

Balcones fault, 564

Bancroft, H., on Key West mine, Nevada, 309

Banded structure of pegmatites, 709

Barlow, A. E., on Sudbury nickel ores, 188, 199

Barrell, Joseph, on intrusives in New England metamorphics, 713

Barton, D. C., on the geologic sig- nificance of arkose deposits, 737

Bastin, E. S., on chrysotile veins of Thetford, 482; review by, 689

Bateman, A. M., Angular inclusions and replacement deposits, 504-520; Geology of the Beatson copper mine, Alaska, 338-368; On intro- ductions, 86-88; The Edtvds tor- sion balance, 84-86; discussion by, 619; on chalcocite of the Bris- tol deposit, 546; on origin of chrysotile veins, 476; on Sudbury nickel deposits, 570, 574; on the origin of Sudbury ores, 173, 199

Bateman, A. M., and McLaughlin, D. H., on ore deposits of Kenne- cott, Alaska, 358; on angular in- cluded fragments at Kennecott, Alaska, 512

Bayley, W. S., on iron in New Jer- sey and North Carolina, 715

Beatson copper mine, Alaska, Geol- ogy of the (Bateman), 338

Bechi, E., on mineralogy of Bottino vein, 543

Beck, R., on succession of minerals in tin-bearing veins, 22

Becker, G. F., on it.clusions in ore deposits, 505

Bell, J. M., on oxidation below water level, 663; on the geology of New Zealand, 752

Bell, Robert, on the origin of Sud- bury ores, 172, 199

Belluci, I., and L., on polydymite, 318

Bergeat and Stelzner, on angular in- clusions in ore deposits, 506

Beryl, large crystals, 705

Besshi mine, Japan, 446

Beyrichite, 318

/

Bibliography of geology of western Oregon, 464; of Persian gypsum deposits, 273

Biquartz-wedge-plate for mineral de- termination, 583

Bitumen, 555

Bixbyite, 117

Black Hills pegmatites, 704

Blake, W. P., on large crystals of al- lanite, 707; on spodumene crystals in Black Hills pegmatites, 704

Blanchard, F., on the Bottino depos- its, 549

Blatchford, T., on petroleum in Western Australia, 164

Blue Ridge pyrolusite, 120

Bomb tests with shale and lime mix- tures, 82

Bore hole record, Oreton, 407

Bornite, diffraction pattern, 25, 29

Pottino lead mines, geology, history and location, 542

Bottino mines, Italy, Primary and secondary ores of the (Sagui), 542

Boulangerite, 545

Boutwell, J. M., on angular inclu- sions in ore deposits, 516

Boydell, H. C., on Grecian magnesite deposits, 417; on variation in mi- crochemical tests, 213

Bragg, W. H., and Bragg, W. L., on spectrometer method of X-ray analysis, 5; on X-ray diffraction,

Braunite, 110, 115, 124, 687, 770

Braunite and hausmannite discrim- inated, 214

Bravais, A., on space-lattices of crys- tal structures, 19

Bravoite, 524; analysis, 525

Brick as a by-product of potash ex- traction, 81

Brock, R. W., Scientific ore finding (editorial), 674

Broderick, T. M., review by, 217

Broegger, W. C., on pegmatites, 698

Brommal, <A., on microchemical methods, 112

Bromoform, 326

Brooks, A. H., on origin of Prince William Sound copper deposits, 362

Brown, J. C., and Heron, A. M., re- view of book by, 689

Bubnoff, S. V., review of book by, 302

Buckley, E. R., on angular inclusions in ore deposits, 516

Buddington, A. F., Alaskan nickel minerals, 521-541

’

784 Index To Volume Xix.

Bugbee, E. E., analysis of ore by, Bults, 652

Buoyancy in the misration of oil,

Busk, H. G., and Mayo, H. T., on Persian gypsum deposits, 259, 273

Butler, B. S., on relation of ore de- posits to different types of in- trusive bodies in Utah, 714; on wurtzite of the San Francisco dis- trict, 70

Calcite vein from Union Springs, New York, 481

California oil field waters (Palmer),

Calkins, F. C., on magmatic segre- gation deposit, 636; on nickel ore in San Diego County, 537

Campbell, J. M., review of paper by,

Campbell, M. R., on water in deep rocks, 391

Campbell, W., on microscopic exam- ination of opaque minerals, 112

Capillarity, nature, 41

Capillarity and oil migration, Some experiments on (Russell), 35

Capillary force, measuring, 39, 41

Capps, S. R., and Johnson, B. L., on the Orca group, 341

Carbon oxysulphid~ 631

Carbonate of iron, Wallen Ridge, 409

Carbonyl sulphide, 631

Case, J. B., report on Huntington Beach oil field, 628

Cassiterite, 690; diffraction pattern, 25, 30

Cayeux, L., on petrography of sed- imentary rocks, 321, 735

Cement and mud, removal from samples, 324

Cement materials, Minnesota, 7

Cerussite, 660

Chacaltaya, Bolivia, The tin deposits of (Lindgren), 223

Chacaltaya district, Bolivia, 224

Chalcedony, diffraction pattern, 25,

Chalcocite, diffraction pattern, 25, 30

Chalcophanite, 117, 770

Chalcopyrite, 187, 210, 543, 655; dif- fraction pattern, 25; formation, 366; Key West mine, 313

Chalcopyrite, Magmatic, Park Coun- ty, Montana (Lovering), 636

Chalcopyrite and specularite, rela- tions, 671

Chalmersite, 187, 209, 355

Charlton, H. W., on the recovery of potash from greensand, 76, 82

Chemical analyses (see Analyses)

Chemistry of magnesite deposits, 416,

Chicagof Island, Alaska, A magmatic sulphur ore from (Kerr), 369

Chloride waters, San Joaquin Valley,

Chlorite, 656

Chromite, diffraction pattern, 24

Chrysotile, origin, 475

Chrysotile vein cutting serpentine,

Cinnabar, 152

Clarke, F. W., and Catlett, Charles,

a “ polydymite,” 314, 317, 527

Classification of ore deposits, 719

Clear Fork formation, Texas, 757

Climate of Latouche, Alaska, 340

Climatic change in South Africa, 664

Clinton formation in Wallen Ridge,

Clinton hematite ores, Notes on the origin of (Stose), 405

Cloister oxidation, 251

Coalinga district, Tertiary forma- tions, 731

Coalinga Tertiary formations, Réle of heavy minerals in the (Reed),

Coals, Chinese, calorimeter and ash tests, 649

Coals from Sze Chuan, China, Pre- liminary report on some (Hub- bard), 641

Coastal Plain, California, ground waters, 630

Cole, G. A. J., review of book by, 400

Coleman, A. P., discussion by, 565; on geology of Sudbury district, 170; on Sudbury nickel deposits, 192, 199

Coleman, A. P., and Willmott, A. B., on pyrrhotite in the Michipicoten Range, 469

Colony, R. J., on magnetite iron de- — of southeastern New York,

Columbite, 117, 770

Contact effects of gabbro and gran- ite on ore deposition, 681

Cook, C. W., on the accumulation of oil, 3

Copper, Sudbury district, 171

Copper Cliff deposit, Sudbury dis- trict, 192

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Index To Volume Xix. 785

Copper deposits, Japan, 434; Parry Sound, 209; Prince William Sound,

Copper enrichment, Cananea district,

Copper King mine, Montana, 640 Copper ore, Beatson mine, Alaska,

Copper ores, Sierra Nevada, 91

Copper ores and diabases of Tran- sylvania, 392

Copper quantity, prediction of, 249

Copper sulphide precipitate, 497

Cordierite, 446

Correlation of well samples by heavy minerals, 748

Corrosive action of oil field waters,

Covellite, diffraction pattern, 25, 30

Cowles process for extraction of alumina, 73

Craig, E. H. C., on origin of gyp- sum, 260, 273

Crean Hill ore deposit, Sudbury district, 192

Creighton mine, Sudbury Ontario, Ore deposition at (Spurr), 275

Creighton mine, Sudbury district, 182, 570

Crosby, W. O., on pegmatites, 608

Crosby, W. O., and Fuller, M. L., on large crystals, 706

Cross-section, Coalinga district, 733; Cuyuna range, 135; Portsmouth mine, 142

Crystallization at Bendigo, force of,

Crystals, gigantic, 704; of pegma- tites, 704

Cubanite, 209, 211, 355

Cullis, C. G., and Edge, A. B., re- view of book by, 99

Cupriferous pyritic deposits, Hitachi mines, Japan (Watanabé and Landwehr), 434

Curtis, J. S., on oxidation below water level, 663

Cuyuna iron range, Minnesota, 466

Cuyuna Range, High temperature manganese veins of the (Thiel), 377

Cuyuna Range pyrolusite, 120

D’Achiardi, A., on stibnite and jame- sonite of the Bottino vein, 545

Dahlblom, Th., discussion by, 389

Dake, C. L., on sand grains, 740, 742

Daly, R. A., on origin of Sudbury ores, 190

Dams in west Texas, Geology and the location of (Patton), 756

Dana, E. S., on a large crystal of al- lanite, 707

Darton, N. H., on geothermal data,

Davey, W. P., on apparatus for X- ray analysis, 6

Davy, W. M., on Bolivian tin-silver deposits, 223, 228

Davy, W. M., and Farnham, C. M., on polydymite, 316; on the micro- scopic examination of ore minerals,

Debye, P., and Scherrer, P., on powder method of X-ray analysis,

Decorah shale, 72; use as fertilizer,

Deerwood iron formation, 134

DeGolyer, E., The occurrence of van- adium and nickel in petroleum, 550-558; What is an economic ge- ologist? (editorial), 473; review by,

DeKalb, C., on igneous rocks of Al- maden, Spain, 146

Delesse, A., on pegmatites, 700, 702

DeMorgan, J., on Persian gypsum de- posits, 259, 273

Depositional basin, indications from heavy minerals 74:

Depth of copper deposition, Beatson mine, Alaska, 365; of water in rocks, 389

Derby, O. A., on manganese ores of Brazil, 119, 129

Determination of opaque ore-minerals by X-ray diffraction patterns (Kerr), 1

Detrital minerals and climate, 737

Diabase, altered, Almaden, 147; anal- ysis, 148; Transylvania, 392

Dickson, C. W., on the origin of Sudbury ores, 172, 199

Differential precipitation, 497

Differentiation of Sudbury nickel eruptive, 176

Diffraction of X-rays, 15

Diffraction patterns, 487; computa- tion, 19; for mineral determination,

Diller, J. S., on Chico beds in Ore- gon, 456; on rock alteration, 379

Dimethylgloxime test for nickel, 373

Diorite, 448

Discussion and informal communica- tions— Arizona asbestos deposits (Samp- son), 386 Contact effects of gabbro and granite on ore deposition, 681 The content of metals in intru- sive magmas (Spurr), 89 The copper ores and diabases of Transylvania (Szentpétery), The education of the geologist,

Fluorite in Bolivian tin mines (Lindgren), 765 Force of crystallization at Ben- digo (Dougherty), 286 Geology of the Sudl bury nickel deposits, 565 The identification of manganese minerals (Fairbanks), 769 Natural gas in Thessaly (Geor- galas), 92 Notes on mineragraphic nique (Fairbanks), 213 Origin of metallic concentrations by magmation (Dunn), 577 The engin of veins of fibrous minerals (Taber), 475 The nermearhjlity of (Lahee), 768; (Dahlblom), 389 Primary relationships and unu- sual chalcopyrite in copper de- posits at Parry Sound, On- tario (Schwartz), 2 Sedimentary phases of Adiron- dack magnetites (Nason), 288 Spectroscopy applied to mineral determination (Douglas), 766 Structural and stratigraphic data

tech-

rocks

of northeast Texas (Lahee),

Study of polished surfaces (Thiel), 582

The Sudbury ore deposits

(Young), 677 X-ray determination of minerals (Mead and Swanson), 486 Docherty, William, prospecting in New Zealand, 750 Dodd, H. V., on the accumulation of oil, 37 Dolomite, effect on magnesite, 429 Double Mountain formation, Dougherty, E. Y., discussion by, 286 Douglas, G. V., discussion by, 7

properties of

Texas,

Index To Volume Xix.

Dresser, J. A., on origin of chrysotile veins, 476

Drilling operations in Oregon, 457

Duane, W., on wave-lengths of K- series of molybdenum, 14

Duluth gabbro, 682

Dumortierite, 711

Dunbar, C. O., review by, 775

Dunn, J. A., discussion by. 577

Dunstan, A. E., analysis of petrole- um ash, 552

Dusky Sound region, New Zealand, mineralized bands, 753

Dynamic metamorphism, relation to Japanese copper deposits, 443

Dysluite, 130

Economic geologist Edenite, 372 Editorial— The Ed6tvés torsion (Bateman), 84 Michrochemical reactions (Lind- gren), 762 On introductions (Bateman), 86 The pitch of rock folds (¥er- mor), 559 Replacement and folding, 281 Science and dogma (Ransome),

, definition, 473

balance

Scientific ore finding (Brock),

A sedimentary problem (Leith),

What is an economic geologist? (DeGolyer), 473

Education of the geologist, 684

Electrical prospecting (review), 217

Electromagnet, use in separating min- erals, 327

Elutriation, 324

Emmons, S. F., on Cananea mining district, 724

Emmons, W. H., on inclusions in ore deposits, 505, 514; on manganese ores of Minnesota, 138; on shape of ore deposits, 443

Enrichment, Balanbanya mines, 394; Beatson mine, Alaska, 358; ‘Grass Valley district, California, 604; Transvaal ilver-lead deposit. 666

Enrichment, Supergene, of copper be- low a lean pyritic sone (White),

Eocene beds, Persia, 262

E6tv6s torsion balance, application to finding ore deposits, 84

Erickson, E. T., analysis by, 535; dis- cussion by, 555

Index To Volume Xix. 787

Eskola, P., on metasomatism, 446

Etchegoin period, 731

Etta pegmatite knob, 704

Eubea, Greece, magnesite deposits, 417

Eugene-Cottage Grove, Oregon, drill- ing for oil, 462

Eutecties, 710

Evolution and distribution of fishes (review), 775

Evolution of ore deposits from ig- neous magmas (review), 585

Experimental production of fibrous veins, 477

Experiments on capillarity and oil migration, Some (Russell), 35

Experiments on zonal precipitation of ores, 407

Fairbanks, E. E., discussion by, 213,

Fairbanks, Ernest, on optical char- acters of Sudbury hornblende, 177

Fars formation, Persia, 262

Faults, Latouche Island, Alaska, 348

Fermor, L. L., The pitch of rock folds (editorial), 559; on man- ganese ores of India, 119

Ferromagnesian minerals, — signifi- cance, 738

Fibrous minerals, origin of veins of,

Filing mineral grains, 330

Fiordland, New Zealand, geology,

Fishes, evolution and distribution, 775

Fishes, the source of petroleum (re- view), 775

Fissures of Grass Valley district, California, 602

Flink, J., on pyrochroite in Sweden,

Fluorite, 226; in Bolivian tin mines,

Folds, pitch of, 559

Force of crystallization, 610; at Ben- digo, 286

Fordham gneiss, 711

Fowlerite, 129

Frailesca, 147

Franklinite, 116, 130; diffraction lines, 488; diffraction pattern, 24

Friedrich, W., and Knipping, P., method of X-ray analysis, 5

Frood mine, Sudbury district, 193,

Gabbro, 370 Gale, H. S., on carbonaceous matter overlying magnesite, 428

Galena, 543, 654; diffraction pattern, 24, 27

Galena limestone, 72

Garfias, V. R., review of book by,

Gaubert, P., review of paper by, 491

Geijer, Per, Replacement and folding (editorial), 281; review by, 687; on the formation of cordierite, 447

Genesis of ore minerals, Key West mine, Nevada, 315; of Sudbury de- posits, 199; of sulphide veins, Creighton mine, Sudbury, 277 (see also Origin)

Genesis of igneous ore deposits (re- view), 585

Gensanne, on temperature in mines, of Alsace, 22

Geochemical objections to Hoefer’s hypothesis, 628

Geocronite, 545

Geologic map, Hitachi mines, Japan, 436 (see also Maps)

Geologic structures (review), 490

Geology of Bottino lead mines, Italy, 542; Chicagof Island, west coast, Alaska. 360: Cooke City district, Montana, 636; Cuyuna range, 133; Dusky Sound region, New Zealand, 750; Grass Valley district, Califor- nia, 595; Hitachi mines, Japan, 435; Kern County magnesite deposit, 415; Long Lake region, Minnesota, 466; Persian gypsum beds, 261; Sudbury district of Ontario, 170; Sudbury nickel deposits, 565; Sze Chuan, China, 642; Wallen Ridge, Virginia, 406

Geology and ore deposits of the Tavoy districts (review), 689

Geology and the location of dams in west Texas (Patton), 756

Geology of the Beatson copper mine, Alaska (Bateman), 338

Georgalas, G. C., Natural gas in Thessaly, 92

Ghase, A., on manganese ores of In- dia, 142

Gilbert, Geoffrey, The relation of hardness to the sequence of the ore minerals, 668-673

Gilligan, A., on petrography of sed- imentary rocks, 735

Goethite, diffraction pattern, 25, 20

Globe, Arizona, chrysotile vein, 480

Gold chloride, 113

Gold ores of Grass Valley, California (Howe), 505

Goldschmidt, V. M., tism, 44)

Goodchild, J. G., on the effect of eo- lian action upon sand, 740

Goodchild, W. H., on origin of Sud- bury ores, 199; review of paper by, 8s

on metasoma-

Goodwin, M., on magnesite, 413 Gordon, S. G., on desilicated granitic pegmatites, 716 Gossan, Beatson mine, Alaska, 359 Gouge breccia, 150 Graham, R. P. D., chrysotile veins, 47 Granite, graphic, 701 Granodiorite, 448 Grant, U. S., and Higgins, D. F., on gabbro on Latouche Island, 363; on the Orca group, 341. Graphic granite, 701 Grass Valley, California, ores of (Howe), 595 Graton, L. C., discussion by, 519

on origin of

The gold

Graywacke, Latouche Island, Alaska,

Great Eastern dike, 309

Green schist, Latouche Island, Alas- ka, 343

Gregory, J. W., and Currie, E., on fossils from Persia, 262, 273

Ground water, chemical work, 69;

lower limits, 66

Ground waters, Notes on (Loughlin),

Grout, F. F., and Broderick, T. M., on pyrrhotite in the Mesabi Range, 46¢

Grubenmann, U., on in rocks, 445

Grunberg, K., on magnesite, 413

Gruner, J. W., review by, 298; on iron ores of Mesabi Range, 136

Gypsite, 260, 266

Gypsum, rate of production, 266; re- cent, 266; varieties of, 260

Gypsum deposits of Egypt, 267

Gypsum deposits of southwestern Persia (Harrison), 259

crystallization

Hackford, J. E., on the contents of the ash of Mexican petroleum, 551

Hall, A. L., on asbestos in South Africa, 388; on chrysotile deposits in the Transvaal, 476

Hall, G. H., on Bolivian silver-tin ores, 223, 228 : Hanson, George, on pyrrhotite in

metamorphic rocks, 469

Index To Volume Xix.

Harder, E. C., on the origin of Clin- ton iron ores, 406

Harder, E. C., and Johnston, A. W., on the geology of east-central Min- nesota, 133, 377

Hardness and abundance of miner- als, 670

Hardness and crystallization of min- erals,

Hardness and insolubility of miner- als, 669

Hardness to the sequence of the ore minerals, The relation of (Gil- bert), 668

Harker, Alfred, review of book by,

Harrison and Eaton, on oil and gas posssibilities of western Oregon,

Harrison, J. V., The gypsum depos- its of southwestern Persia, 2590-274

Hastings, J. B., on pegmatites, 609

Hausmannite, 111, 116, 127, 132, 687,

Hausmannite and braunite discrim- inated, 214

Haiiy, Abbe, on the term pegmatite,

Heavy mineral investigations, Some methods for (Reed), 320

Heavy minerals, classification, 732; lateral persistency, 745; vertical dis- tribution, 745

Heavy minerals in the Coalinga Ter- tiary formations, Réle of (Reed),

Helmhacker, H., on igneous rocks of Almaden, ’Spain, 146

Hematite, 118, 583, 770; diffraction pattern, 24, 30

Hematite ores, Clinton, Notes on the origin of (Stose), 405

Hematite pebbles, 408

Hershey, O. H., on enrichment in Coeur d’Alene district, 666

Hess, F. L., on apatite in Bolivian tungsten deposits, 223; on magne- site of California, 418; on urani- um- ety asphaltite sediments of Utah, 5

Hewett, Db discussion by, 557; on manganese minerals of Oklahoma, 128; on vanadium deposits in Peru,

Hexagonal minerals, diffraction pat- terns, 30

Heyman, A. W., on extraction of pot- ash, 74

Index ‘To

High temperature manganese veins of the Cuyuna Range (Thiel), 377 Hillebrand, W. F., on Peruvian brav- oite, 526

Hisingerite, 212

Historical geology (Schuchert), 589

Hitachi mines, Japan, 434

Hofer-Heimhalt, H., review of book by, 96; on the term petroleum, 556

Hoefer hypothesis of alkaline sul- phide and carbonate waters, 625

Hoffman, Robert, with Wandke, Al- fred, A study of the Sudbury ore deposits, 169-204

Holmes, A., on sedimentary petrog- raphy, 321

Hornblendite, 311

Howe, Ernest, The gold ores of Grass Valley, California, 595-622; on the origin of Sudbury ores, 172

199; on Sudbury nickel deposits, 570, 574 Hubbard, G. D., Preliminary report

on some coals from Sze China, 641-650

Hudson, F. S., on nickel ore in San Diego County, 537

Hiibnerite, 117

Hull, A. W., on calculation of ab- sorption coefficients, 12; on pow- der method of X-ray analysis, 5,

Hume, W. F., on Plio-Miocene beds of Egypt, 262, 273

Hydraulic currents, migration, 53

Hydrogen peroxide, 112

Hydromagnesite, 428

Chuan,

influence on oil

Iddings, J. P., on igneous rocks, 720

Identification tables for minerals, 335

Igneous intrusion, 611

Ilmenite, 130, 583; diffraction pat- tern, 24, 30

Immersion fluids for mineral grains,

Inclusions, Angular, and replacement deposits (Bateman), 504

Inclusions in fissure veins, 678; in magmas, 677

Intergrowth of quartz and feldspar,

Intrusive magmas, metal content, 89

Iron and manganese, relations in Cuy- una Range, 144

Iron formations, origin, 382

Iron ores, manganiferous, 132

Iron ores and iron industry of China (review), 771

Volume Xix.

Iron sulphides in magnetic belts near the Cuyuna Range (Thiel), 466 Irving, D., on inclusions in ore

deposits, 505, 506; on the Leadville district, Colorado, 68 Isometric minerals, 26

Jacobsite, 117

Jamesonite, 544

Jenkins, O. P., on Stevens County, Washington, magnesite deposits,

Jensen, H. I., on oil in the Orallo dis- trict, 163

Johnson, B. L., on mineral deposits of Prince William Sound, Alaska, 360; on mineralization of Latouche Island, Alaska, 348

Johnston, J., and Adams, L. H., on the measurement of temperature in bore holes, 230

Jones, L. J., on the Western Australia, 164

geology of

Kaolin, 71

Kato, T., on deformation of copper deposits, 444

Kaye, G. W. C., on absorption of X- rays, 14

Kemp, J. F., The pegmatites, 697-723; on Adirondack magnetites, 288

Kern County, California, magnesite deposit, 415, 428

Kerndt, K. H. T., on geocronite, 545

Kerr, P. F., A magmatic sulphur ore from Chicagof Island, Alaska, 369- 376; The determination of opaque ore-minerals by X-ray diffraction patterns, 1-34

Key West mine, Nevada, Nickel ores from (Lindgren and Davy), 309

Kikuchi, Y., on cordierite in copper ores, 446

Kircher, A., on increase of tempera- ture with depth, 229

Knapp, A., on movement through water sands, 54

Knight, C. W., on geology of Sud- bury district, 171; on Sudbury nickel ores, 188, 194

Knopf, Adolph, on a magmatic seg- regation deposit, 636

Knox, H. H., on an instance of sec- ondary impoverishment, 663

Koenigsberger, J., on mig of tem- perature in bore holes, 229; on the microscopic determination of min- erals, 3

of oil

Kohlenagerstatten Russlands und Si- biriens (review), 302

Kolar gold field, 561

Koschmann, A. H., review by, 302

Kray, F., on the geology of the Cuy- una Range, 133

Kreyenhagen period, 731

Kyle, J. J., on vanadium in asphalt,

Kyshtym copper deposits, 729

Labradorite, 370

Lahee, F. H., discussion by, 563, 684,

Lamprophyre dike, Latouche Island, Alaska, 346

Landwehr, W. R., with Watanabé, Manjir6, Cupriferous pyritic depos- its, Hitachi mines, Japan, 434-454

Langbansmineralen (review), 687

Larsen, E. S., on determination of non-opaque minerals, 769; on im- mersion media, 332

Laspeyres, H., analysis of polydy- mite, 317

Lateral persistency of heavy mineral assemblages,

Latouche Island, Alaska, climate and topography, 340

Laue, M., method of X-ray analysis,

Launay, L. de, on angular inclusions in ore deposits, 506; on igneous rocks of Almaden, Spain, 146 Leached ore capping, Recent prog- ress with (Morse and Locke), 249 Leadville district, Coiorado, ground water, 65, %

Leith, C. K., A sedimentary problem (ctivarial), 382; review of book by, 3

eek ore deposit, Sudbury district,

Limonite, 118, tern, 29

Lincoln, F. C., on the Beatson mine, cond 350

Lindgren, Waldemar, The tin depos- oa of Chacaltaya, Bolivia, 223- 228; Microchemical reactions (edi- torial), 762; discussions by, 620, 765; on enrichment in the Tintic district, 69; on gold quartz veins of Grass Valley district, Califor- nia, 5905; on inclusions in ore de- posits, 505, 514; on the origin of the Sudburv ores, 173, 190

Lindgren, W., and Davy, W. M.,

140; diffraction pat-

Index To Volume

Nickel ores from Key West mine, Nevada, 309-319

Lindgren, W., and Irving, J. D., on shape of ore deposits, 443

Lindgren, W., Graton, L. C., and Gordon, C. H., on successive min- eral zones, 502

Lithia in spodumene crystals, 704

Lit-par-lit injection, 711

Localization of Beatson copper ores, cause, 365

Location of dams in west Texas, Ge- ology and the (Patton), 756

Locke, Augustus, with Morse, H. W., Recent progress with leached ore capping, 249-258

Loftus, W. K., on fossils from Per- sia, 262, 273; on Persian gypsum deposits, 259, 273

Logan, W., on magnesite in Quebec,

Long Lake region, Minnesota, 466

Longobardi, E., and Comus, N., on vanadium in Argentine petrole- ums, 557

Longwell. C. R., review by, 398; re- view of book by, 490

Loughlin, G. F., Notes on ground waters, 62-71; discussion by, 256; on oxidation zones ot Leadvuile, Colorado, 503

Lovering, T. S., Magmatic chalco- pyrite, Park County, Montana,

Lower Fars formation, 262, 265

Lundberg, Hans, review of book by, McCallie, S. W., on the origin of

Clinton iron ores, 406 McCaughey, W. J., and Fry, W. H., on sedimentarv petrography, 321

McCrae, J., on silver ore, 661 McCoy, A. W., on the accumulation

of oil, 35

MacFarlane, J. M., review of books by, 775

Mackie, W., on feldspars in sedimen- tary rocks as indicators of cli- mate, 737

McLaughlin, D. H., on a magmatic

segregation deposit, 636 McMinnville area, Oregon, 461 Magmas, intrusive, metal content, 89 Magmatic chalcopyrite, Park County,

Montana (Lovering), 636 Magmatic inclusions, 677 Magmatic sulphur ore from Chicagof

Island, Alaska (Kerr), 369

Index To Volume Xix. 791

Magmation, Creighton mine, Sud- bury, 277

Magnesite as a replacement of lime- stone, 421; as a vein filling, 419; composition from different types of deposits, 427; derived from ser- pentine rocks, 417; properties, preparation, and uses, 413; types of, 414

Magnesite brick, effect of impurities,

Magnesite deposits, Types of, and their origin (Bain), 412

Magnetic belts near the Cuyuna Range, Iron sulphides in (Thiel), 66 :

Magnetite, 117; diffraction lines, 488; diffraction pattern, 24; Key West mine, 314

Magnetite ores of Cuyuna Range,

Mascitites of Adirondacks, sedimen- tary phases, 288

Magnusson, N. H., review of paper by, 687

Maitland, A. G., on the geology of Western Australia, 166

Manganese and iron, relations in Cuy- una Range, 144

Manganese minerals: their identifica- tion and paragenesis (Thiel), 107

Manganese minerals, identification,

Manganese veins, High temperature, of the Cuyuna Range (Thiel), 377

Manganiferous iron ores, 132; Cuy- una Range, 377

Manganite, 110, 116, 125

Manganite ore, porous, Minnesota,

Manganosite, 116, 130, 132

Manhattan schist, injections, 711

Maps—Australia, 162; Lower Fars (Miocene) in South Kurdistan, 261 ; Persian gypsum deposits, 259; Prince William Sound, Alaska, 339; Silver-lead veins near Argent Station, Transvaal. 651; Sze Chu- an, China, 644; (see also Geologic map)

Marcasite, 470; diffraction pattern,

4, 29 Marginal deposits compared with off- set deposits, Sudbury district, 196 Martite, manganiferous, 139 Matthew, W. D., on monazite in bio- tite, 709 Maximum thermometer, 230

Mead, W. J., and Swanson, C. Q., discussion by, 486

Measurement of temperatures in deep wells by means of maximum ther- mometers, Apparatus for (Van Orstrand), 229

Medford, Oregon, drilling, 462

Meneghenite, 545, 655

Mercurial thermometers, 230

Mercury ores, The Almaden, and their connection with i igneous rocks (Van der Veen), 146

Merwin, H. E., on immersion media,

Merwin, Lombard, and Allen, on chalmersite, 355; on cubanite, 211

Metallic concentrations, origin by magmation, 577

Metallic minerals in pematites, 710

Metals in intrusive magmas, 89

Methods for heavy mineral tnvestiga- tions (Reed), 320

Mexia fault, 564

Miami, samples of capping, 252

Mica, large crystals, 707

Microchemical reactions, 762

Microcline, large crystals, 706

Microgranodiorite, 449

Microphotographs (see Photomicro- graphs)

Microscopic determination of miner- als, 2

Migration of oil, 35

Miller, W. J., on Adirondack magne- tites, 288

Millerite, 318

Milner, H. B., on correlation of sed- imentary rocks by petrographic methods, 730; on sedimentary pe- trography, 321

Mills, R. V. A., on the migration of oil, 36

Mineragraphic technique, 213

Mineral determination methods, 1

Mineral diffraction patterns. 23, 24

Mineral grains, determination, 333; microscopic examination, 331

Mineral investiaations, Some methods for heavy (Reed), 320

Mineral mixtures, diffraction pat- terns, 31

Mineral zones, successive, formation,

Mineralization, Beatson mine, Alas- ka, age, 354; Cananea copper dis- trict, 724; Dusky Sound region, New Zealand, 753; Hitachi mines, Japan, ores, 439; order of, Chica- goff ores, 375

792 Index

Mineralogy of Bottino lead veins, 542; Grass Valley veins, 508; Transvaal silver-lead ores, 653

Minerals, heavy, in the Coalinga Ter- tiary formations, Role of (Reed),

Minerals

in pegmatites, interrela- tions, 708 Minium, 660 Minnesota shale, Possible potash

production from (Schmitt), 72

Miocene beds, Persia, 262

Miser, H. D., on manganese ores of Arkansas, 127

Moffitt, F. H., on the rocks of La- touche Island, 342

Molybdenum, K-series of waves, 13

Moore, E. S., review by. 301

Morgan, P. G., on the geology of New Zealand, 752

Morozewiez, Joseph, on crystalliza- tion of minerals in magmas, 720

Morse, H. W., discussion by, 257

Morse, H. W., and Locke, Augustus, Recent progress with leached ore capping, 249-258

Mount Hodge pyrrhotite bed, 754

Mounting media for mineral grains,

Mounting minerals, 328

Munn, M. J., on the formation of oil pools, 27

Murdock, J., on chalmersite, 356; on microsc opical determination of opaque minerals, 2, 112, 583; on polydymite, 316

Murray mine, Sudbury district, 188

Nason, F. L., discussions by, 288, 556

Natural gas in Queensland, 162; in Thessaly, 92

Nebel, M. L., on the occurrence of pyrrhotite, 468

Nehalem, Oregon, 460

Newland, D. H., on Adirondack mag- netites, 288; on fluorite in granitic rocks, 716

Newport area, Oregon, 461

New South Wales. prospecting in,

Newton, E., on manganiferous iron ores of the Cuyuna district, 136

Nickel, association with basic igneous rocks, 365; Creighton mine, Sud- bury, 280; in petroleum, 550, 554; Sudbury, 565

Nickel deposits, Chicagoff Island, 369

Nickel eruptive of Sudbury, compo- sition, 176

To Volume

Nickel mineral X, 520. 541

Nickel ogee Alaskan (Budding- ton), 5

Nickel ctl. 522; properties, 531

Nickel ores, Sudbury district, 171

Nickel ores from Key West mine, Nevada (Lindgren and Davy), 309

Nickel sulphides, analyses, 317

Nomland, J. O., on the geology of the Coalinga district, 731

Norite, 184

Notes on ground z

Notes on the origin of Clinton hema- tite ores’ (Stose), 405

Nuclei, angular, 517

Oakland, Oregon, drilling, 462 Occurrence of vanadium and -nickel in peiroleum (DeGolyer), 550

Oil (see Petroleum)

Oil accumulation theories, 35

Oil field waters, California mer),

Oil migration, Some experiments on capillarity and (Russell). 35

waters (Loughlin),

(Pal-

Opaque ore-minerals, Determination by X-ray diffraction patterns (Kerr), 1

Orca group, Alaska, 341

Ore capping, leached, Recent prog- ress with (Morse and Locke), 249

Ore deposition at the Creighton mine, Sudbury, Ontario (Spurr), 275

Ore deposits, Latouche Island, Alas- ka, 348

Ore-minerals, opaque, Determina- tion by X-ray diffraction patterns (Kerr), 1

Ore minereis, The relation of hard-

ness to the sequence of the (Gil- bert), 668 Ore shoots, Grass Valley, California,

600, 605 Orientation-cleavage diagrams, 334 Origin of alkaline carbonate waters of the oil measures, 634; asbestos

deposits, Arizona, 386; Clinton hematite ores, Notes on_ the (Stose), 405; copper deposits,

Prince William Sound, 360; cuprif- erous pyritic deposits, Japan, 448; iron formations, 382; leached zone of Transvaal silver-lead deposit, 665; metallic concentrations by magmation, 577; oil field sulphur waters, 631; ore shoots, Grass Val- ley, California, 601; Persian gyp- sum, 269; primary ores of Bot-

1s

TS OS on he its, if- 48 ; yne sit,

nur Tal- yp- sot-

Index To Volume Xix. 793

tino deposit, 546; quartz of Grass Valley veins, 607; secondary ores of Bottino deposit, 548; Sudbury ore deposits, 169, 172, 565; Trans- vaal silver-lead veins, 658; veins in Cuyuna Range, 381; veins of fibrous minerals, 475 (sce also Genesis)

Orthorhombic minerals, 29

Osbon, C. C., with Soper, E. K., re- view of book by, 301

Ostwald, W., on catalytic decomposi- tion of hydrogen peroxide, 113

Overbeck, R. M., on nickel deposits in Alaska, 524, 535; on the geology of Chicagof Island, Alaska, 360

Oxidation, Beatson mine, Alaska, 358; below water level, Transvaal silver-lead deposit, 663; dissem- inated sulphides, 251; Key West mine, 312; Leadville district, 68

Oxidized zone, Transvaal silver-lead deposits, 659

Oyu, M., on the geology of the Hi- tachi mines, 434

Pack, R. W., on Tertiary formations in San Joaquin Valley, 738

Packard, E. L., on the geology of Oregon, 456

Paige, Sidney, on the geology of the Homestake mine, 714

Palache, C., on pyrochroite in New Jersey, 130

Paleooceanography, 742

Palladium in Key West mine, Nevada,

Palmer, Chase, California oil field waters, 623-6035

Panning in preparation of samples, 325; in separation of minerals, 325

Paragenesis of minerals, Beatson mine, Alaska, 354; Chacaltaya dis- trict, 227; Chicagof sulphide ores, 373; copper ores of Japan, 441; iron sulphides of the Long Lake re- gion, 470; Key West mine, 311, 315; Minnesota iron ores, 136; Parry Sound minerals, 212; Sudbury dis- trict, 198; Transvaal silver-lead ores, 656

Park, James, The pre-Cambrian com- plex and pyrrhotite bands, Dusky Sound, New Zealand, 750-755

Parry Sound copper ores, 209

Patents for extraction of potash, 74

Patton, L. T., Geology and the loca- tion of dams in west Texas, 756-

Peat, occurrence and uses in the United States (review), 301

Pebbles of hematite, 408

Pegmatite dikes, 611

Pegmatites, The (Kemp), 697

Pelloux, A., on silver in Bottino vein,

Penfield, S. L., analysis of pentlandite,

Penfield, S. L., and Stanley, F. C., on amphibole, 683

Pentlandite, 186, 319, 522, 540; anal- ysis, 523; Key West mine, 313

Permeability of rocks, 389; (discus- sion), 7

Persia, southwestern, The gypsum de- posits of (Harrison), 250

Petrography of Goose Lake copper deposit, 637; of the Sudbury nickel eruptive, 175

Petroleum, Prospecting for, in Aus- tralia (Andrews), 157

Petroleum ash, analysis of, 552

Petroleum geology, 686

Petroleum possibilities of western Oregon (Smith), 455

Petroleum resources of the world (review), 215

Petroleum seeps, absence in Oregon,

Petrology for students (review), 399

— A. H., analyses by, 523, 525,

Phillips and Louis, on angular inclu- sions in ore deposits, 506

Photomicrographs—chalcopyrite, 210; Chicagof sulphide ores, 375; copper ores, 442; gabbro, 371; nickel min- erals, 532; nickel ores, Key West mine, 314; Sudbury rocks, 184; Transvaal silver-lead ore, 657

Pilgrim, G. E., on Persian gypsum deposits, 259, 274

Pitch of rock folds, 5590

Plan of main level, Beatson mine, Alaska, 351

Platinum in Key West mine, 310

Plumasite, 716

Polished surfaces, study of, 582

Polydymite, 524, 527; Key West mine, 313, 315, 319; Sudbury, 539.

Pcr)sity of rocks, 390

Portsmouth mine, 141

Poé, Victor, on relation between hardness and insolubility of miner- als,

Posepny, F., on angular inclusioas in ore deposits, 506

Posnjak, E., and Merwin, limonite precipitation, 251

Possible potash production from Min- nesota shale (Schmitt), 72

Potash extraction “from silicate rociks,

H. E., on

Potash production from Minnesota shale (Schmitt), 72

Fotash shale, Minnesota, 72

Pre-Cambrian complex and pyrrhotit2 bands, Dusky Sound, New Zealand (Park), 750

Precipitation, differential, 497; cause,

Precipitation, Zonal, of ores from a mixed solution (Watanabé), 497

Preliminary report on some coals from Sze Chuan, China (Hubbard). E41

Prestwich, J., on depths, 229

Primary and secondary ores of the Bottino mines, Italy (Sagui), 542

Prophanite, 130

Prospecting, electrical, stralia, 157

Prospecting for petroleum in Australia (Andrews), 157

Psilomelane, 111, 115, tions in limonite, 141

Pyrite, 470, 543; diffraction pattern, 24, 29; Key West mine, 313

Pyrite and chalcopyrite, relations, 672

Pyritic, Cupriferous, deposits, Hitachi mines Japan (Watanabé and Land- wehr), 434

Pyrochroite, 130

Pyrolusite, 109,

Pyroxene, 372

Pyrrhotite, 186, 211, 470, 543, 7543 diffraction pattern, 24; in the Lake Superior region, 467

temperature in

217; in Au-

122; concre-

115, 118; laminated,

Quartz, diffraction pattern, 25, 30; large crystals, 706; temperature varieties, 718

Quartz spectroscope, 767

Quartz veins, Grass Valley

Queensland, prospecting in, 162

district,

Ramsay, William, on nickel in petro- leum, 553

Ransome, F. L., Science and dogma (editorial), 205; review by, 99; on angular fragments in ores, 510; on Coeur d’Alene deposits, 653

Index To Volume Xix.

Rastal, R. H., on sedimentary petrog- raphy, 325; on angular inclusions in ore deposits, 506

Reagents for work on manganese min- erals, 112

Recent progress with leached ore cap- ping (Morse and Locke), 249

Redlich, K. A., on Austrian magne- site deposits, 422

Reed, R Réle of heavy minerals in the Coalinga Tertiary formations, 730-749; Some methods for heavy mineral investigations, 320-337

Refractive index of mineral grains, determination of, 333

Relation of hardness to the sequence of the ore minerals (Gilbert), 668

Replacement, Beatson mine, Alaska, 353; Grass Valley district, Califor- nia, 614; in vein formation, 151

and folding (editorial),

Replacement deposits, Angular inclu- sions and (Bateman), 504

Replacement origin of ore veins, 580

Replacement vein of chalcocite in limestone, Kennecott, 513

Report, Preliminary, on some coals from Sze Chuan, China (Hub- bard), 641

Reviews—

Das Erd6l und seine Verwandten (Hofer-Heimhalt), White, 96 The evolution and distribution of fishes (MacFarlane), Dunbar,

ie)

Evolution of ore deposits from ig- neous magmas - (Goodchild), Sosman, 585

Fishes, the source of petroleum (MacFarlane), Dunbar, 775

The genesis of igneous ore depos- its (Campbell), Sosman, 585

Geologic structures (Willis), Longwell, 490

The geology and ore deposits of the Tavoy district, 689

The’ iron ores and iron industry of China (Tegengren), Bain,

Die Kohlenlagerstatten Russlands und Sibiriens (Bubnoff), Kosch- mann, 302

Langbansmineralen fran geologisk — (Magnussen), Geijer,

The occurrence and uses of peat in the United States (Soper and Osbon), Moore, 301

fm

),

); of

ry in,

ds h- isk er,

eat per

Index To Volume Xix.

Petroleum resources of the world (Garfias), DeGolyer, 215 Petrology for students (Harker), Stone, 390 Practical experience in electrical prospecting (Lundberg), Brod- erick, 217 Report on the cupriferous depos- its of Cyprus (Cullis and Edge), Ransome, 99 Rocks and their origins (Cole), Stone, 400 Segregation phenomena of ore- forming solid solutions . (Erz- mischkristalle) and their value in the study of ore deposits and ore dressing (Schneiderhohn), Structural geology (Leith), Long- well, 308 Sur la détermination des minéraux par l’examen microscopique de leur trace laissé sur un corps dur (Gaubert), Schwartz, 491 A textbook of geology, Part II., Historical geology (Schuchert), Twenhofel, 589 Rhodonite, 129 Rich, J. M., on the formation of oil pools, 37 Richardson, Clifford, on the term pe- troleum, 556 Richtmeyer, F. K., on calculation of absorption coefficients, 12 Rickard, T. A., on the Morro Velho gold mine, 562 Ries, H., and Bowen, W. C., on man- ganese minerals at Franklin Fur- nace, 130 Ritchie, Jerome, on enrichment in Transvaal silver-lead deposit, 666 Roberts, H. M., and Longyear, R. D., on the origin of Sudbury ores, 172,

Rock folds, pitch of, 550

Rocks, permeability, 389

Rocks and their origins (review), 400

Rogers, A. F., on manganese minerals of California, 128

Rogers, G. S., on California oil field waters, 627

Réle of heavy minerals in the Co- alinga Tertiary formations (Reed),

Rumpf, J., on Austrian magnesite, 421 Russell, W. L., Some experiments on capillarity and oil migration, 35-61

Sagui, C. L., Primary and secondary

ores of the Bottino mines, Italy,

St. Paul area, Oregon, 461

Samples, preparation for study, 323

Sampling copper deposits, 255; sed- imentary rocks, 321

Sampson, Edward, discussion by, 386

Sanders, J. M., on phosphorus in Mex- ican oil, 553

Santa Margarita period, 731

Sayles, R. W., on need for deep earth temperature data, 229

Schenck, Hubert, on geology of Ne- halem area, Oregon, 460

Schist, green, Latouche Island, Alas-

ka, 343

Schmitt, H. A., Possible potash pro- duction from Minnesota shale, 72- J

Schneiderhohn, H., review of paper by, 298; on variation in microchem- ical tests, 213

Schoenflies, A., on space-groups of crystal structures, 19

Schuchert, Charles, review of book by, 589

Schwartz, G. M., discussions by, 209, 681; review by, 491; on an occur- rence of pyrrhotite, 468

Science and dogma (editorial), 208

Scientific notes and news, 103, 221, 305, 403, 493, 592, 603, 779

Scientific ore finding (editorial), 674

Scott, G. S., on the Sudbury ores,

Screening in preparation of samples,

Secondary, Primary and, ores of the Bottino mines, Italy. (Sagui), 542

Sections—Beatson mine, Alaska, 351; Clinton formation in Wallen Ridge, 407; contact of diabase with fault breccia, 149; Creighton mine, Sud- bury district, 183; diabase, altered, 147; gouge a 150; mercury ore of Almaden, 152, 154; Tertiary formations of ie ad district, 732 (see also Cross sections)

Sedimentary petrography, 321

Sedimentary phases of Adirondack magnetites, 288

Sedimentary problem, 382

Segregation phenomena of ore-form- ing solid solutions (review), 208

Sequence of the ore minerals, The relation of hardness to the (Gil- bert), 668

Shale, Minnesota, Possible potash pro- duction from (Schmitt), 72

796 Index To

hand, S. J., on Persian gypsum de- posits, 259, 274

Sherzer, W. H., on various types of sand grains, 740

Siderite, 655

Sideroplesite, 656

Silicification in Tintic Mountains, 256

Silver, 654

Silver sulphide, 544

Silver-lead deposit, A (Wagner), 651

Simonin, L., on the Bottino mines, Italy, 542

Slate, Latouche Island, Alaska, 342

Smith, J. P., on climatic relations of Tertiary and Quaternary faunas of the California region, 730

Smith, W. D., Petroleum possibilities of western Oregon, 455-465

Smith, W. D., and Packard, E. L., on the geology of Oregon, 456

Smythe, C. H., Jr., on the origin of Clinton ores, 405

Society of Economic Geologists, 102, 220, 304, 401, 692

Sodium chloride, diffraction pattern, 24; diffraction photograph, 19

Some experiments on capillarity and oil migration (Russell), 35

Some methods for heavy mineral in- vestigations (Reed), 320

Soper, E. K., and Osbon, C. C., re- view of book by, 301

Sorby, H. C., on the examination of sedimentary rocks, 320

Sosman, R. B., review by, 585

South Australia, prospecting in, 163

Spectrometer method of X-ray anal- ysis, 5

Spectroscopy applied to mineral de- termination, 766

Specularite, 671

Spencer, L. J., on fluorite in Bolivian tin mines, 765

Sphalerite, 187; diffraction 24; Key West mine, 314

Spinel, diffraction pattern, 24

Spurr, J. E., The content of metals in intrusive magmas, 89; Ore de- position at the Creighton mine, Sud- bury, Ontario, 275-280; discussions by, 80, 518, 621; on angular frag- ments in ore deposits, 504, 507; on inclusions in fissure veins, 678; on metals in pegmatites, 710; on pegmatites, 699; on vein formation,

Transvaal

pattern,

Stahl, A. F., on Persian gypsum de- posits, 250, 274

Volume Xix.

Stannous chloride, 112

Steiger, G., discussion by, 555

Stelzner, A. W., on Bolivian ore de- posits, 224

Stevens County, Washington, magne- site deposits, 422

Stickney, A. W., on pyritic copper deposits of Kyshtym, Russia, 663,

Stillwell, F. L., on angular inclusions in ore deposits, 515; on the force of growing crystals, 610

Stilpnomelane, 380

Stobie mine, Sudbury district, 193

Stone, J. B., reviews by, 399, 400

Stony Creek granite, 712

Stose, G. W., Notes on the origin of Clinton hematite ores, 405-411; on manganese ores of Virginia, 123

Stratigraphy of western Oregon, 458

Streak of a mineral, determination by,

Structural geology (review), 398

Structure-section across Coalinga dis- trict, 733

Stuart, M., on the origin of gypsum, 269, 273

Study of the Sudbury ore deposits (Wandke and Hoffman), 169

Stutzer, O., on pegmatites, 699

Styria, Austria, magnesite deposits,

Successive mineral zones, formation,

Sudbury, Ontario, Ore deposition at the Creighton mine (Spurr), 275

Sudbury nickel deposits, geology, 565

Sudbury nickel eruptive, 175; altera- tions in, 179

Sudbury ore deposits, A study of (Wandke and Hoffman), 169

Sudbury ore deposits, 677

Sudbury series, 171

— waters, San Joaquin Valley,

Sulphide minerals, Chicagof Island,

Sulphide waters of oil fields, forma- tion, 628 Sulphides in the Long Lake region, 471 Sulphur ore, A magmatic, from Chic- agof Island, Alaska (Kerr), 369 Supergene enrichment of copper be- low a lean pyritic zone (White), 724 Sze Chuan, China, Preliminary re- port on some coals from (Hubbard),

Szentpétery, S., discussion by, 392

yy

a

rm

e-

Index To Volume Xix. 797

Taber, Stephen, The origin of veins of fibrous minerals (discussion), 475; on the force of growing crystals, 610; on the origin of veins of the asbestiform minerals, 477

Tables—analyses of minerals for de- termination of microchemical reac- tions, 109; analyses of mixtures of py rolusite, psilomelane, and man- ganite, 121; analyses of samples from the Coalinga district, 733, 747; analyses of samples of Decorah and Galena formations, 74; borings in Cananea copper district, 726; Co- alinga Tertiary, historical deduc- tions, 731; coals, Chinese, calori- meter and ash tests, 649; composi- tion of Sudbury nickel eruptive, 176; data regarding the samples of capping, 252; determination of man- ganese minerals, 114; experiments on migration of oil, 41; galena dif- fraction pattern, 27; magmatic dif- ferentiation in Hitachi mining dis- trict, 452; manganese minerals, re- lations, 131; manganese minerals and their properties, 108; optimum weights of samples for X-ray anal- ysis, 12; Oregon stratigraphy, 458; paragenesis and occurrence of min- erals, Sudbury district, 198; prop- erties of nickel minerals, 530; screen analysis of Olean sandstone, 52; sodium chloride diffraction pattern, 21; Sze Chuan coals, properties,

Taconite, 134

Tameta, B., and Yamane, S., on rocks of Hitachi mines, Japan, 435

Tantalite, 117, 770

Tasmania, prospecting in, 161

Tasmanite, 161

Tavoy district, geology and ore depos- its, 689

Tegengren, F. R., review of book by,

Temblor period, 731

Temperatures in deep wells, Appara- tus for the measurement of, by means of maximum thermometers Van Orstrand), 229

Ten:antite and tetrahedrite, distin- guished by spectroscope, 768

Tertiary formations of Coalinga dis- trict, 731

Tetragonal minerals, diffraction pat- terns, 30

Tetrahedrite, diffraction pattern, 28

Texas, northeastern, petroleum area,

Carl von, on carbon oxysulphide,

Thermochemical objections to Hoe- fer’s hypothesis, 627

Thermometers, mercurial, 230

Thetford chrysotile vein, 480

Thiel, G. A., High temperature man- ganese veins of the Cuyuna Range, 377-381 ; Iron sulphides in magnetic belts near the Cuyuna Range, 466- 472; The manganese minerals: their ide ntification and paragenesis, 107- 145; analyses by, 121; discussion by, 582; on the migration of oil,

Thompson, A. P., on copper ores of Diucktown, 440

Tickell, F. G., on the correlative value of the heavy minerals, 730

Tin deposits of Chacaltaya, Bolivia (Lindgren), 22

Tintic district, Utah, ground water,

Titaniferous magnetites, 291 ; analyses,

Tolman, C. F., and Rogers, A. F., on magmatic sulphide ores, 376, 449, 537, 639; polydymite, 316; on the origin of Sudburv ores. 172. 199

Topaz, orientation diagram, 334

Topography of Latouche Island, Alaska, 340

Tourmaline, 226, 547; large crystals, 705, 710

Transporting agents, indications from heavy minerals, 730

Transvaal Silver and. Base Metals Limited, 652

Transvaal silver-lead deposit (Wag- ner), 651

Transylvania copper deposits, 392

Tremolitization, Chicagof ores, 375

Trikkala basin, Greece, 92

Trueman, J. D., on determination of folded crystalline rocks, 740

Tulare period, 731

Turner, H. W., and Rogers, A. F., on a magmatic segregation deposit, 636

Tutton, A. E. H., on space-groups of crystal structures, 19

Twelvetrees, W. H., on chrysotile veins from Tasmania, 479

Twenhofel, W. H., review by, 5890

Types of magnesite deposits and their origin (Bain), 412

Tyrone, samples of capping, 253

798 Index

Urmi series, 262

Valdez group, Alaska, 341

Vanadium and nickel in petroleum, The occurrence of (DeGolyer), 550

Vanadium in coal, 556

Van der Veen, The Almaden mercury ores and their connection with ig- neous rocks, 146-156

Van Hise, C. R,, on pegmatites, 699

Van Hise, C. R. and Leith, C. K., on intrusives in Marquette and Menom- inee Ranges, 381; on rocks of Cuy- una iron Range,

Van Orstrand, C. E., Apparatus for the si area of temperatures in deep wells by means of maximum thermometers, 229-248

Veindikes, 611; Creighton mine, Sud- bury, 275

Veins, Chacaltaya district, Bolivia, 25; Cuyuna Range, 378; Grass Val- ley district, California, 507; of fi- brous minerals, origin, 475

Vertical distribution of heavy miner- als, 744

Veta Hierro, 225

Victoria, prospecting in, 161

Violarite, 319, 527

Vogt, J. H. L., on pegmatites, 699; on origin of Sudbury ores, 199, 574

Wagner, P. A., A Transvaal silver- lead deposit, 651-667

Waldport area, Oregon, 462

Walker, T. L., on differentiation of the Sudbury nickel eruptive, 176

Wallen Ridge, geology, 407

Wandke, Alfred, and Hoffman, Rob- ert, A study of the Sudbury ore de- posits, 169-204; discussion by A. P. Coleman, 565; discussion, 677; on polydymite, 529

Washburn, E. W., and Navias, L., on the relations of quartz and chalce- dony, 30

Washburne, C. W., on oil prospects and geology of northwestern Ore- gon, 455; on the accumulation of oil, 35

Watanabé, Manjir6, Zonal tion of ores from a tion, 497-503

Watanabé, Manjir6é, and Landwehr, W. R., Cupriferous pyritic depos- its, Hitachi mines, Japan, 434-454

Waters of Californian oil fields, 629

Watson, T. L., and Wherry, E. T,, on pyrolusite from Virginia, 126

Weinschenk, E., on cordierite, 446;

precipita- mixed solu-

on magnesite deposits of Liesing,

Wentworth, C. K., pebbles, 740 Western Australia,

on rounding of prospecting in,

White, C. H., Supergene enrichment of copper below a lean pyritic sone, 724-729

White, David, review by, 96

White, I. C., on deep wells in Appa- lachian oil fields, 230

Whitehead, W. L., on angular inclu- sions in ore deposits, 516

Wiley, H. W., on elutriation, 324 -

Williams, E. H,, on tourmaline crys- tals, 710

Williams, G. H., on pegmatites, 699

Willis, Bailey, review of book by,

Wilson, M. E., on Argenteuil magne- site deposits, 423

Winchell, N. H., on rocks of Cuy- una iron range, 467

Wolframite, 117, 690

Worthington mine, deposits, 195

Wright, F. E., on examination of opaque minerals in polarized light, 214; on the microscopic determina- tion of minerals, 4; on wall rock from Creighton mine, Sudbury, 27:

Wright, F. E., and Larsen, E. S., on quartz as a geological thermometer,

Sudbury nickel

Wulfenite, 660

X-ray analysis of minerals, 2, 4

X-ray determination of minerals, 486

X-ray diffraction outfit, 7

X-ray diffraction patterns, The de- termination of opaque ore-minerals by (Kerr), I

Young, J W., discussion by, 677

Young. S W., and Moore, N. P., on minerals of copper ores, 440

Youngman, R. H., on magnesite, 413

Zapffe, C., on pyrrhotite in the Gun- flint Range, 468

Ziegler, Victor, on spodumene crys- tals in Black Hills pegmatites, 704

Zies, E. G., Allen, E. T., and Mer- win, H. E., on conversion of zinc sulphide into copper sulphide, 501

Zinc blende, 544

Zinc sulphide precipitate, 497

Zonal precipitation of ores from a mixed solution (Watanabé), 497