Silver in the United States (MR-34)

E.T. McKnight, W.L. Newman, H. Klemic & A.V. Heyl · 1979 · Silver Maps

USGS map showing all silver districts in the contiguous US containing 100,000+ troy ounces of production. Districts categorized by size (100K-5M oz, 5M-50M…

Public-domain full text preserved in the Mountain Man Mining Library. Original source: pubs.usgs.gov.

(rat) 911,t41 ;LA. j fo wl sr' DEPARTMENT OF THE INTERIOR TO ACCOMPANY MAP MR- 34 rd.?a UNITED STATES GEOLOGICAL SURVEY SILVER IN THE UNITED STATES (Exclusive of Alaska and Hawaii) By E. T. McKnight, W. L. Newman, Harry Klemic, and A. V. Heyl, Jr. Introduction The productive silver districts in the United States (exclusive of Alaska and Hawaii) are shown on the accompanying map. Only those districts known or believed to have contained 100,000 troy ounces or more silver are shown. Three size categories, based on production and estimated reserves, are distin­ guished and indicated by size of symbols: districts containing 100,000 to 5 million ounces, those con­ taining 5 million to 50 million ounces, and those containing more than 50 million ounces. Symbols show the approximate centers of the districts. Some of the more prominent districts are identi­ fied by name on the map, and all are numbered to correspond to the index. Because a name established through common usage may not be the legal name of the mining district, several names are given in the index for some localities. The index, arranged al­ phabetically by States, includes a brief description of major geologic features for most districts. Both published and unpublished data were used, and at least one reference is given for each locality if reports on it have been published. Occurrence and mineralogy of silver Silver is primarily an accompanier of other metals, notably lead, copper, and gold. In the de­ posits of these metals it usually occurs as a minor constituent, commonly of only byproduct importance. There are, however, all gradations to districts in which the chief values have been in silver. Though most of these have been mined out, one of the greatest, the ilver Belt in the Coeur d'Alene region in Idaho, is c rrently the major silver-producing district of the U ited States. Many districts commonly classed as silver districts nevertheless carry im­ portant values in other metals, such as gold in the Comstock and Tonopah districts in Nevada, and copper, lead, and antimony in the Silver Belt. In relatively few districts are virtually all the values in silver, and these have accounted for only a minor proportion of the total production (Merrill, 1930). Silver is usually a companion of zinc only where there is associated lead or copper. However, the small amount of zinc sulfide that occurs in some of the major lead deposits of southeast Missouri contains a significant amount of silver. Byproduct silver in lead sulfide deposits occurs in "argentiferous galena" as minute inclusions of argentite (Ag2S), tetrahedrite ( (Cu,Fe,Zn,Ag)12Sb 4S13)), tennantite ( (Cu,Fe,Zn,Ag) 12As4S13) ), or possibly other silver-bearing minerals. It may also occur in larger grains of tetrahedrite or tennantite, interstitial to the other ore-forming minerals. By increase of tetrahedrite relative to galena, the type of deposit grades to that of the Silver Belt. Byproduct silver in copper deposits is presumably an "impurity" in chalcopyrite, bornite, enargite, or chalcocite; but in deposits richer in silver, the silver occurs in tetrahe­ drite, tennantite, or stromeyerite (CuAgS). Most gold mined in the United States contains some alloyed silver, the amount ranging from less than 10 percent to as much as 60 percent in ex­ ceptional cases. Gold from the Mother Lode Belt in California commonly contains 10 to 20 percent silver; that from the Homestake mine in South Dakota averages about 20 percent. The largest proportion of silver is contained in the gold from the epithermal precious metal deposits. Placer gold contains less silver than gold in the lode from which it was derived. The difference has commonly been explained as due to loss of silver during exposures in the zone of weathering, but it may be due to a primary difference between the gold in deep-seated portions of a lode and that in the apical portions from which the placer gold was derived (Mertie, 1940). One large dredging opera­ tion in California in recent years produced gold containing about 7 percent silver, but some placer gold is known from California containing only 2 to 3 percent silver. In addition to the silver that is alloyed with native gold, many gold deposits contain appreciable amounts of silver minerals. Such deposits grade to predominantly silver deposits with increase in the proportion of silver-bearing minerals. In primary gold and silver deposits, these minerals include tetrahedrite, tennantite, argentite, hessite (Ag2Te), polybasite (Ag16Sb2Si1), pyrargyrite (Ag3SbS3), prou­ stite (Ag3AsS3), stephanite (Ag5SbS4), pearceite Ag16 As2S11), miargyrite (AgSbS2), and other silver-bear­ ing sulfides, including galena. During oxidation of primary deposits, the silver is dissolved and reprecipitated as cerargyrite (AgC1), embolite (Ag(C1,Br)), bromyrite (AgBr), iodyrite (AgI), native silver, argentite, argentite, stromeyerite, or one or more of the combinations of silver with antimony, arsenic, and sulfur that have been listed above as primary silver minerals. Where silver is a byproduct of other metals, it may be recovered from ores that are extremely low grade in terms of silver. Whether it is recovered at all may depend upon the metallurgical technology

used in processing the other metals. The lead ore of southeast Missouri contains so little silver that the cost of recovering if from the lead bullion is greater than the value of the silver. For some uses, however, silver-free lead is required, which necessitates separation of the silver from a substantial part of the large amount of lead produced from this district. The common ratio of one ounce of silver per ton of lead from southeast Missouri is equivalent to only 0.03 oz of silver per ton of crude ore. Similarly, the porphyry copper deposits contain a very low percentage of silver (0.02 to 0.11 oz recovered per ton ore), yet so great a tonnage of this material is mined and processed annually that this type of deposit is currently a major source of silver. In the refining methods that are currently used on the metals from most western ores, silver is recovered at relatively little additional cost, hence it is an especially valuable byproduct or coproduct that may determine whether a deposit can be worked or not. Primary copper ores of various geologic types have yielded much silver from ores that, with a few minor exceptions, have been rather lean in this constituent. Most lead-bearing ores of the western states are richer in silver values, which in some deposits equal or exceed the combined values of the other products. Lead ore of the Tintic district, Utah, is especially argentiferous; much of it has averaged 30 to 40 oz of silver per ton (Lindgren and Loughlin, 1919). Such ore approaches, in tenor of silver, the higher grades of dominantly silver ores. Gold ores have produced less silver than lead and copper ores. They show a range from a negligible but recoverable trace of silver to ores in which silver predominates. Whereas much of the ore mined principally for silver has been of the lowest average grade that could be economically worked, some districts, parti­ cularly during their youth, have yielded shipments of very rich ores. The Comstock district, Nevada, is especially famous for its bonanza ore; some ship­ ments yielded perhaps 1,000 ounces of silver per ton of ore with nearly comparable values in gold. Tonnages of this grade were relatively small, however, and the average grade for even the richest mines of the Comstock Lode was less than 40 oz of silver per ton.. Ore from the Sunshine mine and several adjacent properties that were worked as a milling unit in the Silver Belt of the Coeur d'Alene region, Idaho, averaged 49 oz of silver per ton (and 4 percent lead) for 51,000 tons of ore mined in 1946; and the Sunshine mine, in an earlier year, 1937, had yielded 47.5 oz of silver per ton from a quarter of a million tons of ore. During oxidation of silver-bearing deposits near the surface, the silver is normally taken into solution by ground waters, carried downward, and repreci­ pitated in an enriched zone of secondary minerals. The richest zones are concentrated from near the outcrop to some distance below the groundwater table, with varying mineralogy at different levels. The grade of ore decreases unevenly at greater depth until the unenriched primary ores are reached. Gold and copper, if present, are enriched along with the silver, whereas the lead shows no pronounced change in tenor, though the primary sulfide is com­ monly oxidized to the carbonate above the water table. In the early days of western mining when transportation was primitive, such shallow oxidized deposits were particularly attractive because of the high values that could be concentrated in a relatively small weight of ore. Many deposits, too low grade to be profitable when the primary ore was reached, were worked out and abandoned. Others, although the amount of silver diminished with depth, proved workable as primary lead deposits in which the silver could be recovered as a byproduct or coproduct. This type of deposit has, over the years, yielded far more silver than the oxidized ores. The oxidized surficial zones of a few massive sulfide copper deposits, such as the Iron Mountain deposit in the West Shasta district, California, were worked princi­ pally for silver in their early history. Most copper deposits, however, were worked as enriched copper deposits in which the silver contributed much to the value of the ore. Part of the copper and silver in the porphyry copper deposits is derived from enrichment of extremely low grade disseminated primary material. The grade of secondarily enriched silver ores shows wide fluctuations within any given deposit. Gouging of thin pay streaks by the hand-mining methods used in the early days of the West yielded fabulously rich ore for relatively small tonnages; but for many deposits, particularly those worked by small mining operations, no record of grade has been preserved. Assays of very rich ore that have been cited mean little in the absence of a tonnage to which the grade could be applied. Some of the richest ore for which there is record was mined from Treasure Hill in the White Pine district, Nevada. Here, one lot of 22 tons was valued at more than $5,000 per ton, equivalent to about 3800 oz of silver per ton. Very rich shipments are also recorded from the Yankee Girl mine in the Red Mountain district of Colorado, where one lot of 10 tons carried 3,270 oz of silver per ton, and another of 6 tons carried 5,300 oz per ton; several carloads of ore contained 1500 to 3000 oz per ton. The mine average was, of course, much lower, the ore from an 80-foot interval between 2 levels averag­ ing 242 oz of silver per ton. Though there is lack of agreement as to the extent of enrichment in Red Mountain ores, it is probable that at least part of the richest ore was secondary. This ore was unusual in that copper was the other major metal. Other examples of enriched ore include that from the Granite-Bi­ metallic mine at Philipsburg, Montana, which carried 50 to 1,000 oz of silver per ton; the nBridaliChamber" are from the Lake Valley district:New Mexico, where several carloads ran more than 400 oz of silver per ton; the early chloride ore at Austin, Nevada, running 1,500 oz per ton; and the shipping ore from the California Rand mine at Randsburg, California, the first 49,000 tons of which averaged 106 oz of silver per ton. Types of silver deposits The association of silver with other metals is reflected in the wide variation in its geologic occur­ rence. Virtually all silver-bearing deposits, however, are near or in igneous rocks to which they must be

genetically related. The argentiferous lead, most of the copper, and many of the gold and silver deposits are typically in or near stocks or small batholiths of intermediate to acidic composition, though in some areas the largest known intrusive bodies are sills and dikes of this composition. An important class of precious-metal deposits, in which gold values pre­ dominate in some and silver in others, occurs as shallow veins in Tertiary extrusive rocks of inter­ mediate to acidic composition. Although intrusive rocks are generally not exposed with such deposits, indications are commonly present that an intrusive mass of comparable composition is buried at no great depth. Some silver-bearing copper deposits are asso­ ciated with- mafic igneous rocks, both intrusive and extrusive. Silver-bearing deposits may lie within the igneous masses to which they are genetically related or in the adjacent older rocks. In some districts they appear in both, and furthermore may be of more than one type in either environment. There is a tendency for the copper deposits to occur in or immediately next to the intru­ sive igneous rocks, for the lead and lead-zinc deposits to occur in the adjacent sedimentary rocks, and for the gold and dominantly silver deposits to occur in Tertiary lava rocks. However, the exceptions are numerous and important. The physical and chemical conditions at the site of ore deposition are controlling factors which affect the metals differently, depending on their chemical properties. To judge from the wide range of conditions under which silver is deposited in some form or other, this metal may be somewhat less exacting in its requirements for deposition than the metals with which it is commonly associated. However, the relatively high value of silver, making feasible its recovery from deposits in which it occurs in very low concentration, may make such contrasts with other metals more apparent than real. In the following account of silver-bearing deposits, only those types of base- and precious-metal de­ posits will be discussed which have yielded relatively large amounts of silver from individual districts. A complete account of silver-producing ores would encompass nearly every type of deposit that has produced gold, silver, copper, or lead in the United States but would tend to obscure the salient features of the geologic occurrence of silver. Deposits in intrusive igneous rocks: Silverbearing deposits that lie within the parent plutonic igneous mass may take several forms. Commonly such deposits are veins or lodes along fractures and faults, with variable replacement of the broken wallrock material. Large silver production has come from copper deposits of this type at Butte, Montana, and Lordsburg, New Mexico; from such lead-zinc deposits as those in the Butte, Barker, and Cataract districts, Montana; and from silver deposits, all secondarily enriched, in the Reese River (Austin), Nevada, Blind Spring, California, and Philipsburg, Montana, dis­ tricts. The Granite-Bimetallic mine at Philipsburg was a famous silver lode, but its rich secondary ores have been long exhausted. The Butte district is especially noteworthy in that although its silver output has been exceeded at different times by that from other districts, its total silver production exceeds that of any other district in the United States. This production has been obtained largely as a byproduct or coproduct from base-metal ores which are roughly segregated into an inner copper core and an outer zinc-lead zone in the quartz rnonzonite country rock. In the early days of the district, however, much silver was recovered from oxidized ores near the surface, particularly in the zinc-lead zone. Gold-quartz veins have yielded much silver from associated silver minerals in the Nevada City dis­ trict, California. A substantial amount has come from veins in the intrusive granodiorite, though perhaps more has come from similar veins in the adjacent country rock. Another type of silver -bearing deposit that occurs within the parent igneous rock is exemplified by the porphyry copper deposits of the West. In these, the primary copper minerals, chalcopyrite and locally bornite, and associated pyrite are disseminated in small grains or in small indefinite and irregularly anastomosing veinlets through large blocks in igneous stocks or other irregular igneous bodies of inter­ mediate to silicic composition. The primary material is commonly too low grade to be exploited, but with varying amounts of secondary enrichment in which chalcocite replaces part of the primary minerals, the mass becomes a low-grade copper ore that can be profitable if mined in large tonnages. The trace of silver present in the original ore is enriched along with the copper and is normally recovered in the refining of the copper. The silver content varies from one deposit to another, and in a few instances its value would not repay the cost of recovering it. In overall silver content the porphyry copper deposits rank individually somewhat below several other types of deposits, but at the present time some of them rank high among the silver-producing deposits. Those with important silver content include Bingham, Utah; Ely, Nevada; and Ajo, San Manuel, Miami, Ray, and Morenci, Arizona. The deposits at Morenci might better be des­ cribed as intermediate in type between the usual porphyry copper deposits and the lode type of de­ posits. The ore-bearing ground contains both lowgrade lodes and disseminated ore minerals in the blocks between the lodes, but the deposits are workable only because of the secondary enrichment that has affected both. The Kelley copper mine at Butte exploits a block of ground in which the primary ore deposits show a similar structural setting. An unusual type of silver-bearing deposit in an igneous stock was found in the San Francisco district, Utah. Here, in the Cactus copper mine, the ore, relatively low grade in both copper and silver, occurred in the interstices and replacing the fragments of a steeply plunging breccia pipe formed along a fault zone in quartz monzonite. Deposits in igneous dikes of the same general magmatic derivation as the ore deposits will be discussed below, as they are more closely related to the veins and lodes in the invaded country rock.

Deposits in older rocks adjacent to intrusive rocks. Silver-bearing deposits that lie in the country rock near intrusive igneous masses to which they are genetically related constitute a large and varied group. The type of deposit is influenced by the lithologic character of the enclosing rock and by pre-existing structural features. Massive pyritic ores of copper with some asso­ ciated zinc, which replace siliceous wall rocks, have yielded large amounts of byproduct silver in a few districts of large ore production. At Jerome, Ariz., a great pyritic replacement pipe containing chalcopyrite and a little sphalerite occurred in schist immediately bordering a gabbro stock. This deposit, only recently mined out, averaged only 1 to 2 oz of silver per ton of ore. In the West Shasta district, California, fiat lenticular pyritic bodies of similar composition re­ place a slightly metamorphosed soda rhyolite. Although much of the silver produced here has been a byproduct of primary ores, the surficial oxidized zone of one deposit was first worked for secondary silver ores in the early history of the camp. Disseminated grains of secondary copper sulfide showing much the same relation to the enclosing country rock as those in the adjacent porphyry copper masses occur in schist immediately bordering the porphyry in the Miami and Ray copper districts, Arizona. These disseminated sulfides in schist have undergone the same secondary enrichment as those in the porphyry, and the ores in the two kinds of host rocks have been mined together without distinction. Part of the low-grade primary ore in depth at Ray consists of disseminated pyrite and chalcopyrite in a diabase sill which is intruded by the copper-bearing porphyry. Pyrometasomatic deposits replacing limestone close to or immediately bordering on intrusive igneous masses have yielded predominantly copper or copperzinc ores. As silver producers, such deposits are not usually large enough to compensate for the low silver content of copper ores, but a few have been large enough to contain appreciable quantities of silver; among these the currently producing Pima and adjacent mines in the Pima district, Arizona, are good examples. Districts that contain pyrometasomatic deposits commonly also contain other types of deposits with higher silver content. As the different types of deposits are not usually differentiated in thepublished statistics of silver production, the relative un­ importance of the pyrometasomatic deposits is not usually apparent. Replacement deposits in limestone adjacent to faults, fissures, igneous dikes, or other types of feeder channels at some distance from the main intrusive igneous rock form a major class of silverproducing deposits. They have various attitudes and shapes, lying either along or across the bedding of the limestone. Some copper deposits of this type contain silver, but the deposits of the Bisbee district, Arizona, are the only outstanding examples. Copper replacement ores in limestone have produced con­ siderable silver also from the Globe district, Ariz­ ona, and, in recent years, from the Magma mine in the Pioneer district, Arizona. The lead-zinc replacement deposits in limestone, on the other hand, include many famous districts of major silver pro­ duction, such as Leadville, Aspen, and Red Cliff, Colorado; Bingham, Park City, and Tintic, Utah; Eureka, Nevada; Philipsburg, Montana; and numerous others of only slightly lesser importance. There is some segregation of lead-zinc replacement bodies even in such dominantly copper camps as Bisbee; and some of the lead-zinc districts carry variable amounts of copper ore, more or less segregated in separate bodies. There are all gradations in silver content from districts which contain very little, such as Metaline, Washington, to others, such as Tintic, in which silver may equal or exceed the base metals in value. In a few districts, replacement deposits in limestone are dominantly silver ores, as at Tomb­ stone, Arizona; Cortez, Nevada; Lake Valley and Kingston, New Mexico; and the Presidio mine at Shafter, Texas. In these silver districts the deposits have been variable to thoroughly oxidized; and al­ though the Tombstone ores appear to have been secondarily enriched from primary lead-zinc de­ posits that were perhaps high in silver, the other deposits mentioned appear to have been dominantly silver ores even before enrichment. The bulk of the silver-bearing replacement deposits in limestone are in Paleozoic strata. Replacement deposits in carbonate rocks com­ monly contain some gold along with the other metals, and in such deposits in the Black Hills of South Dakota, gold becomes the dominant product. Thus, the deposits in the Bald Mountain district, in which the ore minerals replace Cambrian dolomite and dolomitic quartzite, contain appreciable amounts of silver as a byproduct of the gold. Those of the Homestake mine (Whitewood district) replace a cum­ mingtonite-chlorite schist which was derived from Precambrian dolomitic limestone; and although the silver content here amounts to only a few cents per ton, the large tonnage of ore treated in this leading gold mine of the United States has accounted for a relatively large production of silver. Although silver-bearing deposits in carbonate rock usually form massive replacement deposits, in some instances they may be narrowly confined to crosscutting channels to form vein and lode deposits. Such are the silver (stromeyerite) veins which occur in dolomite and were worked in the early days in the Clark Mountain (Ivanpah) district, California. Lode deposits in many districts crosscut several types of rocks and commonly thicken where they cross lime­ stone, thus forming gradations to the replacement deposits, as along some of the famous lead-silver lodes in the Park City district, Utah. In more refractory rocks that are less reactive with the ore-forming solutions than limestone or dolomite, vein and lode deposits along faults or fractures are the usual forms taken by silver-bearing deposits in the country rock adjacent to the parent igneous intrusives. Commonly, replacement of the country rock has been equally as effective as openspace filling in emplacement of the ore, though the replaced rock is usually rather narrowly confined to the immediate vicinity of the feeding channels. Practi4

cally all kinds of country rocks have been mineralized at some place or other, and in many districts several kinds have been mineralized. Lodes in quartzite have accounted for such famous silver producing deposits as those in the Coeur d' Alene region, Idaho. Here, the host rock is a fine-grained sericitic quartzite of Precambrian age. Lead-zinc deposits with substantial silver content accuunt for much of the silver, but,in the Silver Belt,tetrahedrite rich in silver becomes abundant relative to the associated lead mineral, and silver becomes the primary product. In consequence, the Coeur d'Alene region has led in the production of silver since development of the Silver Belt about 1930. Lodes in quartzite have also yielded much silver from lead-zinc deposits in the Park City region, Utah, and from the oxidized silver deposits that were worked in the early days at Pioche, Nevada. Argillaceous rocks do not, in general, have the requisite physical strength to maintain permeable fractures for movement of ore-bearing solutions. At a few places, however, such rocks had been sufficiently hardened by metamorphism or by a small carbonate content to permit formation of important silver-bear­ ing lodes. Lead-zinc lodes in argillite and calcareous argillite have accounted for much silver from the Warm Springs and Mineral Hill districts, Idaho. Tetrahedr ite -galena lodes, rich in silver and occurring in a slate host rock, were at one time very productive of silver from both oxidized and primary ores in certain mines of the Bayhorse district, Idaho. The oxidized silver veins in the Candelaria district, Nevada, occur, in large part, in argillite which has been somewhat hardened by a varying content of calcium carbonate. Schist forms the wall rock of lodes and veins that contain the zinc-lead-silver deposits at the Iron King mine in the Big Bug district, Arizona. Gneiss forms the wall rock of the silver-lead-zinc lodes in the Neihart district, Montana and, with subordinate interbanded schist, of such similar lodes as those in the Wallapai district, Arizona, and Silver Plume district, Colorado, and of gold-silver lodes in the Central City district, Colorado. Igneous rocks older than and genetically unrelated to the enclosed lodes are the host rock for some silver-bearing deposits. In the Magma copper mine of the Pioneer district, Arizona, the lode is confined within a thick diabase sill over much of its extent. In the Sugar Loaf-St. Kevin district, Colorado, the silver lodes, secondarily enriched, occur chiefly in a highly altered Precambrian granite, though the lodes are probably of early Tertiary age. No single gold mining district along the 120-mile­ long Mother Lode belt in California has been a major producer of silver, but the total silver content of the gold bullion from the belt has been appreciable. The gold veins and lodes in this belt, which lies west of the Sierra Nevada batholith, have cut various types of older rocks, including black slate, greenstone, various schists, and serpentine. In some of the lodes in greenstone and serpentine, replacement of the country rock near the quartz veins has been the dominant mode of ore emplacement. Deposits in igneous dikes. An important class of silver-bearing deposits occurs in or along igneous dikes of the same general magmatic source as the plutonic mass to which the ores are related. These dikes cut the country rock into which the plutonic mass was intruded. Physical and chemical conditions within the dikes were similar to those prevailing at com­ parable locations in several types of noncalcareous country rock, hence, the mineralogical and structural features of these deposits are quite similar to those in the veins and lodes that cut the country rock. In nearly all dike deposits, it is clear that fault movement along and later than the dike has opened the ground to the ore solutions. Replacement of the broken igneous rock has been a large factor in emplacement of the ore. Those dike deposits that have produced much silver have been lead-zinc deposits that usually contain appreciable silver in the primary ore. Outstanding examples occur in the Tybo district, Nevada, the Central and Willow Creek districts, New Mexico, and the Tombstone district, Arizona. In the Willow Creek district the country rock is Precambrian diabase, but the deposit, now worked out, was along a shear zone in schistose material believed to have been derived from injected Precambrian granite or from hybrid material formed by partial assimilation of the diabase by the granite magma. In the Tombstone district, deposits occurred in and along the sheared Contention dike where it cuts shale and sandstone. Prior to 1886 these yielded more than $10,000,000, chiefly in silver and gold, though they also contained much lead. The ores were oxidized and secondarily enriched in silver. Deposits in predominantly volcanic rocks. The most characteristic single geologic habitat of silver is in the vein and lode deposits in Tertiary lava rocks. Such deposits contain both silver and gold, and locally important quantities of base metals as well. Although a few silver districts contain only nominal amounts of the other metals, the most productive silver districts have contained appreciable gold, and there are all gradations to districts in which the chief value has been in gold. The deposits occur in volcanic rocks ranging in composition from andesite to rhyolite. The silver districts include such famous camps as Tonopah, ComstoCk (in part), Tuscarora, Rochester, Fairview, and Wonder, Nevada; Calico and Mojave, California; Silver City, DeLamar, and Yankee Fork, Idaho; and Mogollon, New Mexico. In some districts secondary enrichment has been effective in concentrating the silver values; in others, such as Tonopah, the pro­ duction has come largely from primary deposits. The base-metal lodes in the Tertiary volcanic rocks of the San Juan Mountains, "Colorado, carry both silver and gold, which were mainly responsible for early exploitation of the deposits. Major silver-pro­ ducing camps, still active, are Creede, where the ores are in rhyolite, and the Telluride-Sneffels district, where the host rock is chiefly andesitic-breccia and flows. Five other districts in the San Juan region have each produced more than 5 million ounces of silver. In all of these San Juan districts, lead, zinc, and some copper have been important coproducts.

Similar deposits, except for such details as a unique tourmaline gangue, have yielded the large silver output from the Wickes district in Montana, where the major production (Alta mine) took place in the 1880's and 1890's. There, however, the lodes are in Upper Cretaceous quartz latites, closely adjacent to the Boulder Batholith of only slightly later age to which the deposits are genetically related. Such deposits are transitional to the lodes described above, which are in older rocks but obviously related in origin to an intrusive igneous mass. In regions of Tertiary volcanism, some silver lodes are known which occur in much older rocks but which resemble in structure and mineralogical and chemical composition the precious metal lodes in Tertiary lavas. Such lodes are believed to be of the same origin as the more typical ones in the lavas. An example is the Randsburg district, California, where the deposits occur in Precambrian schist but are evidently related to Miocene volcanism, as evidenced in a volcanic pipe, dikes, and sills, ranging in composition from rhyolite to diabase, which intrude the country rocks. The gold-silver veins of the Marysville district, Montana, are in hornstone that was formed by contact metamorphism of limestone adjacent to a small intrusive stock of Laramide age; the veins, however, are probably not related genetically to this stock but to a later period of Tertiary mineralization which was preceded by intrusion of dikes and sills of dacite (Knopf, 1913). Lodes may also occur along fault contacts between Tertiary volcanic rocks and older rocks, as in the San Francisco district, Utah, where the Hornsilver lode lies between Tertiary quartz latite flows and lower Paleozoic limestone. Similar relations exist along parts of the Comstock lode and in the adjacent Silver City district, Nevada, where the footwall rocks are Mesozoic metabasalt. Such deposits usually resemble those enclosed entirely within the Tertiary lavas. An uncommon type of silver-bearing deposit is found in volcanic breccia pipes or chimneys of Tertiary age. In several such deposits in the Red Mountain district, Colorado, the ore filled the inter­ stices and replaced the country rock in the breccia or in a cylindrical envelope zone along the contact with the volcanic rocks immediately surrounding the breccia. These deposits were particularly famous for their richness in silver and copper, but they also contained lead and some zinc. The highest grade ore consisted of stromeyerite and bornite, and was probably secondarily enriched in silver to some extent. The deposits lay on the periphery of a large caldera in the general vicinity of several small plugs of quartz latite porphyry. Another deposit of apparently similar type has been worked at the Flathead mine, Hog Heaven district, Montana. Here, silver-lead ore replaced the igneous country rock in a stockwork formed by two or three intersecting systems of irregular frac­ tures in a porphyritic latite intrusive mass of Terti­ ary age. The primary ore was dominantly galena and pyrite but contained the rare silver mineral matildite (AgBiS2). However, the deposit owes its value chiefly to extensive secondary enrichment of the silver. Silver is also associated with extrusive igneous rocks of pre-Tertiary age. The copper deposits of the Keweenaw Peninsula, Michigan, occur both in basalt flows of Precambrian age and in conglomerate closely associated with these flows. In the igneous rock the ore minerals fill the openings and replace fractured amygdaloid layers or occur along crosscutting and bedding veins. In the conglomerates they are dissemi­ nated in the matrix. The chief ore mineral is native copper, but a little native silver is present and has been recovered as a byproduct. Output of the latter is large because of the high production from these copper deposits. Although opinions as to origin have not been in unanimous agreement, most geologists propose that ascending hydrothermal solutions have either extracted the metals from the igneous rocks at lower levels and deposited them at higher levels, or have carried the metals up from the magmatic reservoir from which the mafic igneous rocks and allied types were derived. Deposits on fault contacts between intrusive and igneous rocks. In many of the mining districts that contain silver deposits in Tertiary lava rocks, no intrusive igneous rocks are exposed to which the ores can be genetically related. In other districts, as in the San Juan Mountains of Colorado, small plutonic igneous masses intrusive into the lava rocks are exposed within the general region of ore deposition, but their distribution relative to the ore deposits is haphazard. In both types of mineralized areas, the silver-bearing lodes occur along tectonic faults of considerable lateral extent and appear to have been derived from a deep-seated source. Segregation of the mineralizing solutions from a deeply buried intrusive mass, which may or may not have delivered satellitic offshoots into the crustal zone, offers the best explanation for the origin of the ore. In a few scattered districts of Tertiary volcanism, structural weakening of the crust in the neighborhood of small intrusive igneous bodies has localized tectonic breaks along the borders of such masses. In these places a silver lode may lie along a fault contact between the lava rocks and the intrusive igneous mass to which it is, indirectly, related. An outstanding example is the Comstock Lode, in Nevada. Though most of the bonanza deposits in this district were in subsidiary breaks within the andesite hanging wall, some of the ore was along a great fault, including a part of its course where the footwall is a small intrusive stock of diorite, believed to be closely related to the ore in origin and time of emplacement. The ores otherwise resemble those in the Tertiary lava rocks. Deposits of uncertain or disputed igneous affili­ ation. With minor exceptions, the lead-zinc deposits in the Mississippi Valley and west of the Blue Ridge in Tennessee and Virginia contain at most only nominal amounts of silver. In most of these mining districts no exposures or other indications of intrusive igneous activity are present. In the southeast Missouri and Southern Illinois-Kentucky districts, however, mafic igneous dikes, sills, and pipes are exposed; and explosion centers (diatremes) are a further indication

of both mafic and silicic igneous intrusives. These features are not closely related in position to the ore deposits, and their genetic significance is questioned by some. The districts involved, however, are the ones that contain the most silver. In spite of a low silver content, the total amount of silver produced from the lead ores of southeast Missouri has been large owing to the huge tonnage of ore that has been mined. Although most of the silver has been obtained from galena averaging about 1 oz per ton, the silver is particularly enriched in the small amount of sphalerite in these deposits, ranging up to 25 oz per ton of zinc sulfide concentrates. The ore is disseminated or forms small replacement lenses in dolomite and is the lowest grade of lead ore mined in the United States. Galena concentrates from the fluorspar-zinc-lead deposits of the Southern Illinois-Kentucky district contain 5 to 15 oz silver per ton, though the production of silver has not been large owing to the subordinate percentage of galena in the ores. These deposits include bedded replacement deposits and veins in limestone. A few deposits of apparently sedimentary origin contain appreciable silver, as, for example, the copper deposits in bedded siltstone and shale of the White Pine area, Ontonagon County, Michigan, and particularly the silver deposits in bedded sandstone of the Silver Reef district in Utah. In the latter dis­ trict, the ore minerals are largely restricted to sandstone strata that contain abundant plant debris. Although a direct hydrothermal origin from igneous sources is not completely ruled out, the silver in these deposits was possibly derived in a short sedi­ mentary cycle from typical deposits of igneous origin, from igneous tuffs, or perhaps from igneous exhala­ tions that entered the drainage systems during de­ position of the host rocks. Placer deposits. Placer gold always yields by­ product silver, although the total amount is not large in any individual placer basin. Placers on the west slope of the Sierra Nevada, however, have accounted for an appreciable amount of silver. The gold with its alloyed silver was derived both from the Mother Lode belt and from the East Belt, which is an indefinite, broad zone lying east of the Mother Lode and characterized by many small but rich "pockets" of gold. Age of silver deposits Silver is found in deposits ranging in age from Precambrian to late Tertiary. In the United States more deposits are of Laramide or Tertiary age than of earlier age, because of the prevalence of igneous intrusive activity during this span of geologic time. Earlier periods of silver deposition coincided with orogeny and igneous intrusion at the end of the Jurassic Period or during the Cretaceous Period in the West, and at the end of the Paleozoic Era in the Appalachian region. The latter region, however, has yielded very little silver. Precambrian silver deposits occur in important districts as Jerome and Big Bug, Arizona, Willow Creek, New Mexico, the Michigan copper districts, and probably the Coeur d'Alene region in Idaho (Long and others, 1960). Distribution of silver deposits Most of the deposits containing silver are within a few broadly defined structural units: The western slopes of the Sierra Nevada and their extension into the Klamath Mountain block of California and Oregon; the Basin and Range region of Nevada, western Utah, southeastern California, southern Arizona, southern New Mexico, and Western Texas; the Rocky Mountain Cordillera, extending from New Mexico to the Canadian border, with a notable absence of any deposits in Wyoming; and the Black Hills uplift in South Dakota. There are, however, scattered silver-bearing deposits outside these four areas, among which the copper deposits in the Keweenaw Peninsula of Michigan and the lead deposits of southeast Missouri have yielded important amounts of silver as a by-product. The main productive lead-zinc deposits of the Appalachian Cordillera contain only insignificant amounts of silver or none, but a few scattered deposits that have been relatively small producers have contained silver in ratios more characteristic of the Western States; there is also a little silver associated with eastern copper deposits. Index District or region Lat. N. Long. W. ARIZONA 1. Union Pass (Katherine mine). 35°17' 114°25' Veins in Precambrian granite and Tertiary rhyolite dikes. Wilson and others, 1934; Hewett and others, 1936. 2. Wallapai (Chloride Camp). Veins 35°25' 114°11' in Precambrian granite, gneiss, schist, and amphibolite. Dings, 1951; Thomas, 1949. 3. Wallapai (Cerbat Camp). Veins in 35°19' 114°08' Precambrian granite, gneiss, schist, and amphibolite. Dings, 1951; Thomas, 1949. 4. San Francisco (Oatman). Bypro- 35°01' 114°24' duct of gold. Veins in Tertiary andesite. Wilson and others, 1934. 5. Owens (McCracken mine). Veins 34°28' 113°46' in Precambrian quartz-mica schist. Bancroft, 1911. 6. Eureka (Bagdad area). Byproduct 34°35' 113°13' of base metals. Vein and replace­ ment lenses along faults in Pre­ cambrian schists; by-product of copper in disseminated ore, partly enriched, in upper Creta­ ceous or Tertiary quartz monzo­ nite. Anderson and others, 1956. 7. Jerome (Verde) (United Verde 34°45' 112°07' mine). Byproduct of copper. Replacement pipe in Precambrian schist adjacent to Precambrian gabbro stock. Anderson and Creasey, 1958.

Index (cont'd.) ARIZONA (cont'd.) 8. Black Hills. Veins in Precam- 34°40' 112°13' brian schist. Lindgren, 1926; Hewett and others, 1936. 9. Agua Fria. Byproduct of copper. 34°26' 112°10' Replacement lenses in Precambrian schist. Lindgren, 1926; Hewett and others, 1936. 10: Big Bug (Iron King mine). By34°30' 112°15! product of base metals. Replace­ ment lenses in silicified Pre­ cambrian schist. Anderson and Creasey, 1958. 11. Walker. Veins in early Tertiary 34°27' 112°23' (?) granodiorite and Precam­ brian amphibolite schist. Lind­ gren, 1926; Hewett and others, 12. Hassayampa. Veins in Precam- 34°25' 112°30' brian amphibolite schist and granite. Lindgren, 1926; Hewett and others, 1936. 13. Turkey Creek. Veins in Pre- 34°22' 112°23' cambrian schist. Lindgren, 1926; Hewett and others, 1936. 14. Peck (Ocotillo).Veins in quart34°16' 112°19' zite lenses in Precambrian schist. Lindgren, 1926; Hewett and others, 1936. 15. Pine Grove. Veins in Precam- 34°14' 112°21' brian granodiorite, diorite, and schist. Lindgren, 1926; Hewett and others, 1936. 16. Tiger. Veins in Precambrian 34°11' 112°21' schist and lower ,Tertiary (?) granodiorite. Lindgren, 1926; Hewett and others, 1936. 17. Black Canyon. Veins in Precam- 34°13' 112°10' brian schist. Wilson and others, 1934; Lindgren, 1926, Hewett and others, 1936. 18. Old Tip Top. Veins in Pre- 34°03' 112°14' cambrian granite and peg­ matite. Lindgren, 1926. 19. Vulture (Vulture mine). Bypro- 33049 7 112°50' duct of gold. Veins in Precambrian schist. Wilson and others, 1934; Hewett and others, 1936. 20. Osborn. Veins in Tertiary ande- 33 37' 112°52' site and rhyolite. Tenney, 1928. 21. Kofa. Byproduct of gold. Lodes 33°18' 113°58' along brecciated fault zones in Tertiary andesite. Wilson and others, 1934; Hewett and others, 22. Silver. Veins along faults bet33°06' 114°36' ween Precambrian granite and lower Tertiary (?) andesitic ARIZONA (cont'd.) breccia and tuff, or in Precam­ brian schist. Wilson, 1951a. 23. Castle Dome. Veins along fault 33°02' 114°11' zones in and along diorite porphyry dikes of Cretaceous (?) age and in Cretaceous shale. Wilson, 1951b. 24. Ajo (New Cornelia mine). By- 32°22' 112°52' product of copper. Disseminated ore in lower Tertiary (?) quartz monzonite. Gilluly, 1946. 25. Silver Bell. Contact metamor- 32°25' 111°31' phic deposits in Carboniferous (?) limestone; byproduct of cop­ per in disseminated deposits in Laramide(?) porphyry stock. Stewart, 1912; Richard and Courtright, 1954. 26. Superior (Pioneer) (Magma 33°18' 111°06' mine). Replacement veins along faults in quartz-monzonite por­ phyry, diabase, and quartzite; bedded replacement deposits in Devonian limestone. Short and others, 1943; Webster, 1958. 27. Globe. Byproduct of copper, 33°25' 110°47' Veins and replacement bodies along faults in Precambrian quartizite and limestone and Paleozoic limestone and diabase sills. Ransome, 1903; Tenney, 1935; Peterson, 1950. 27a. Miami. Byproduct of copper. 33°24' 110°53' Disseminated ore in Precam­ brian schist adjacent to granite porphyry intrusive, and in lower Tertiary(?) quartz mon­ zonite porphyry and granite porphyry masses. Ransome, 1919; Tenney, 1935; Peterson and others, 1951. 28. Ray (Mineral Creek). In part, 33°10' 111°00' byproduct of copper indissemMated ore (secondarily en­ riched) in Precambrian schist and diabase and in adjacent Tertiary quartz monzonite por­ phyry stock; in part, with lead ore. Ransome, 1919. 29. Banner. Vein-replacement 33°04' 110°48' bodies in and bordering a shear­ ed dike of rhyolite porphyry; replacement bodies in Pennsy­ lvanian limestone along bedding and bordering igneous masses; byproduct of copper in contact metamorphic deposits in Car­ boniferous limestone. Kiersch, 1951; Ross, 1925a.

Index (cont'd.) ARIZONA (cont'd.) ARIZONA (cont'd.) quartz latite porphyry. Sch­ rader, 1915. 30. Aravaipa. Veins and replace- 32°59' 110°20' 39. Helvetia. Byproduct of copper: 31°52' 110°47' ment bodies on fault breccia in Contact metamorphic deposits, Pennsylvanian limestone; veins in part along fault zones, in in intrusive rhyolite. Ross, Pennsylvanian and Permian 1925b, Wilson, 1950a. limestone. Creasey and Quick, 31. Copper Mountain (Morenci). 33°04' 109°20' 1955; Schrader, 1915. Byproduct of copper. Contact 40. Empire. Replacement bodies 31°53' 110°36' metamorphic deposits in Paleo­ and pipes along fissures in Perzoic limestone, and secondarily mian limestone, and at contacts enriched disseminated ore in with porphyry dikes and sills. lower Tertiary porphyry. LindWilson, 1951c. gren, 1905. 41. Cochise (Johnson Camp). Bedd- 32°06' 110°04' 32. Bunker Hill (Blue Bird mine). 32°46' 110°28' ed replacement bodies, mantos, Vein in granodiorite stock of and chimneys at or near interLaramide (7) age. Kuhn, 1951. sections of fissures in Cambrian 33. Old Hat (Mammoth). Replace32°42' 110°42' limestone. Cooper, 1950. ment veins along shear zones 42. Tombstone. Replacement bodies 31°42' 110°04' in Tertiary(?), rhyolite, and in along faults and fissures, partly Precambrian (?) quartz mon­ on tops of folds, in Pennsylvanian zonite; by-product of copper, and Lower Cretaceous limedisseminated ore in Precam­ stones, quartzites, and shales, brian quartz monzonite and and in sheared granodiorite Laramide (7) monzonite por­ dikes. Butler and others, 1938. phyry. Creasey, 1950; Schwartz, 43. Turquoise. Replacement bodies 31°44' 109°49' along fractures and faults in 34. Pima (San Xavier mine area) 31°58' 111°05' Pennsylvanian limestone. WilByproduct of base metals. Reson, 1927; 1951d. placement pipes along fissures and contact metamorphic de44. Bisbee (Warren). Replacement 31°27' 1090541 posits in Mississippian and Perbodies along bedding or cross mian limestones. Wilson, 1950b; fractures, or adjacent to porHuttl, 1958. phyry dikes and sills in Devonian and Mississippian lime­ 34a. Pima (Esperanza mine). By31°51' 111°08' stones; byproduct of copper in product of copper. Dissemi­ disseminated ore (secondarily nated ore in Tertiary quartz enriched in Upper Jurassic(?) monzonite, intrusive andesite, granite porphyry stock. Hogue and in intruded Cretaceous or and Wilson, 1950. Tertiary clastic rocks. Schmitt and others, 1959. 45. Swisshelm. Replacement bodies 31°42' 109°32' in fractured Pennsylvanian 35. Oro Blanco (Momana mine). Re31°28' 111°14' limestone above a diorite por­ placement lode along shear phyry sill. Galbraith and Lor­ zone between intrusive diorite ing, 1951. and igneous-pebble conglome­ rate, or in latter. Fowler, 1938. 46. California (Hilltop mine). Veins 31°59' 109°14' and contact deposits. 36. Patagonia (Duquesne) (including 31°23' 110°42' Mowry mine). Contact meta47. Ash Peak. Veins along diabase 32°46' 109°15' morphic and replacement dedike on fault in Tertiary andeposits in Devonian and Pennsylsite. Lines, 1940. vanian limestones adjacent to CALIFORNIA intrusive quartz monzonite. Sch­ rader, 1915. 1. Squaw Creek (Blue Ledge mine). 41°58' 123°06' Byproduct of copper. Replace­ 37. Harshaw (Trench and Flux 31°28' 110°44' ment lenses along contact betmines). Veins along shear zones ween Devonian or older quartzin intrusive igneous rocks and hornblende schist and sericite replacement bodies in Pennsyl­ schist. Shenon, 1933. vanian(?) limestone. Schrader, 2. Dillon Creek (Klamath River, in 41°35' 123°39' part) (Siskon mine). Byproduct 38. Tyndall. Veins in quartz dio- 31°36' 110°52' of gold from gossan of massive rite, quartz monzonite, and

Index (cont'd.) CALIFORNIA (cont'd.) pyritic replacement deposit in tuff. United States Bureau of Mines, 1953-57. 3. Island Mountain (Island Moun- 40°02' 123°30' tain mine). Byproduct of copper. Replacement deposits along shear zones (thrust fault?) in Jurassic (?) shale and graywacke. Stinson, 4. French Gulch -Deadwood (Brown 400431 122°43' Bear, Washington, and Niagara Summit mines). Byproduct of lode and placer gold. Ferguson, 1914; Averill, 1933. 5. South Fork (Chicago mine). Veins 40°32' 122°35' along faults in granodior ite batholith of Lower Cretaceous (?) age. Tucker, 1922. 6. West Shasta (Flat Creek). By- 40°44' 122°30' product of copper. Bedded re­ placement bodies in Devonian soda rhyolite along axes of broad folds. Kinkel and others, 1956. 7. Bully Hill. Byproduct of copper. 40°48' 122°13' Replacement bodies in Triassic rhyolite along shear zones on anticlinal crest and flanks. Boyle, 1915; Graton, 1910; Albers and Robertson, 1961. 8. Cow Creek (Ingot) (Afterthought 40°44' 122°04' mine). Replacement bodies in fractured soda rhyolite and adjacent limy shale of Triassic age. Albers, 1953. 9. Lights Canyon (Engels, Superior 40°13' 120°45' mines). Byproduct of copper. Re­ placements of intrusion breccia along contacts of Upper Jurassic gabbro and quartz diorite with Carboniferous(?) andesite and keratophyre; veins and stockworks in Upper Jurassic quartz monzonite. Knopf, 1935; Ander­ son, 1931. 10. Genessee (Walker mine). By- 390581 120°40' product of copper. Replacement bodies in highly metamorphosed Carboniferous argillaceous rocks adjacent to contact of Upper Jurassic quartz diorite. Averill, 1937; Knopf, 1935. 11. Sierra City (Sierra Buttes 39°35' 120°39' mine). Byproduct of lode gold. Averill, 1942. 12. Washington (Graniteville) (Spa39024' 120°46' nish, Gaston mines). Byproduct of lode and placer gold. MacBoyle, 1919; Logan, 1941. CALIFORNIA (cont'd.) 13. Alleghany. Byproduct of lode and 39°28' 120°50' placer gold. Ferguson and Gannett, 1932. 14. Slate Creek (LaPorte) Bypro- 39°40' 120°571 duct of placer gold. Pettee,1880; Lindgren, 1911. 15. Yankee Hill. Replacement 39°41' 121°26' bodies near fault zone along schistosity in Carboniferous(?) metavolcanic rocks. Eric, 1948. 16. Oroville. Byproduct of placer 39°27' 121°37' gold. Clark, 1957; Logan, 1930a; Aubury, 1910. 17. Hammonton (Yuba River). By- 39°12' 121°26' product of placer gold. Clark, 1957; Logan, 1930b; Aubury, 18. Nevada City. Byproduct of lode 39°15' 120°59' and placer gold. Johnston, 1940; Lindgren, 1896. 19. Ophir. Byproduct of lode and 38°52' 121°08' placer gold. Logan, 1936. 20. Calistoga (Silverado, Palisade 38°38' 122°35' mines). Fissure veins in andesite. Averill, 1929. 21. Folsom. Byproduct of placer 38°38' 121°13' gold. Clark, 1957; Carlson, 1955; Aubury, 1910. 22. Placerville. Byproduct of lode 38°43' 120°48' and placer gold. Clark and Carlson, 1956. 23. Plymouth-Jackson. Byproduct 38°24' 120°49' of lode and placer gold. Knopf, 1929; Denton and Clark, 1954. 24. Ione (Newton mine). Byproduct 38°21' 120°54' of copper. Replacement deposit along schistosity fault in altered Jurassic volcanic rocks. Heyl and Eric, 1948. 25. Campo Seco (Penn mine). By- 38°14' 120°52' product of copper. Replacement bodies along schistosity in Jurassic metavolcanic rocks. Heyl and others, 1948. 26. Mokelumne Hill. Byproduct of 38°17' 120°43' lode and placer gold. Julihn and Horton, 1938. 27. Monitor. Braided fissure zones 38°40' 119°42' and impregnations in kaolinized andesite. Logan, 1922. 28. Mount Patterson (Silverado and 38°27' 119017' Kentuck mines). Veins along fault between andesite and rhyolite. Sampson, 1940. 29. Masonic. Byproduct of lode gold. 38°22' 119°07' Sampson, 1940.

Index (cont'd.) CALIFORNIA (cont'd.) 30. Bodie. Byproduct of gold. Veins 38°13' 119°01' in andesite. Sampson, 1940. 31. Angels Camp. Byproduct of lode 38°04' 120°32' and placer gold. Eric and others, 1955; Knopf, 1929; Julihn and Horton, 1938. 32. West Belt (Quail Hill area). 37°57' 120°44' Replacement bodies along shear zones near or along borders of Upper Jurassic stocks of felsite and quartz porphyry. Heyl, 1948b. 33. Copperopolis (Keystone-Union, 37059' 120°39' North Keystone mines). Bypro­ duct of copper. Replacement bodies along fault zone along schistosity of Jurassic(?) slates and metavolcanic schists. Heyl, 1948a. 34. Carson Hill (Carson Hill mine). 38°01' 120°30' Byproduct of lode and placer gold. Eric and others, 1955; Knopf, 1929; Julihn and Horton, 35. Columbia Basin. Byproduct of 38°02' 120°25' placer gold. Julihn and Horton, 36. Sonora. Byproduct of lode and 37°59' 120°23' placer gold. Julihn and Horton, 1940, Eric and others, 1955. 37. Soulsbyville-Tuolumne. Bypro- 37°59' 120°15' duct of lode gold. Julihn and Horton, 1940. 38. Jamestown. Byproduct of lode 37°56' 120026' and placer gold. Julihn and Horton, 1940; Knopf, 1929. 39. Shawmut (Eagle-Shawmut mine). 37°52' 120°24' Byproduct of lode and placer gold. Julihn and Horton, 1940; Knopf, 1929. 40. Groveland-Big Oak Flat. Bypro- 37°50' 120°15' duct of placer and lode gold. Julihn and Horton, 1940. 41. Hunter Valley. Replacement 37°34' 120°15' bodies along shear zones in schistose felsite tuff and breccia of Carbonaceous to Jurassic ages. Eric and Cox, 1948. 42. Hites Cove. Byproduct of lode 37°39' 119°52' and placer gold. Julihn and Horton, 1940; Bowen and Gray, 43. Boot Jack. Veins in Upper 37°25' 119°53' Jurassic(?) granite. Julihn and Horton, 1940; Bowen and Gray, CALIFORNIA (cont'd.) 44. Mammoth Lakes. Byproduct of 37°37' 118°59' lode gold. Sampson, 1940. 45. Chidago. Veins in granite, rhyo- 37°42' 118°34' lite, and limestone. Sampson, 46. Blind Spring. Veins alongparal- 37°46' 118°29' lel faults in Jurassic granitic stock. Ransome, 1940. 47. Bishop Creek. Byproduct of 37°24' 118°43' tungsten and copper. Contact metamorphic deposits in Paleozoic marble. Bateman, 1956. 48. Black Canyon. Replacement len- 37°20' 118°12' ses in fissures in Paleozoic(?) limestone. Norman and Ste­ wart, 1951. 49. Cerro Gordo. Replacement 36°32' 117°48' bodies near axis of plunging anticline in Devonian limestone. Knopf, 1918a; Norman and Stewart, 1951. 50. Lee (Santa Rosa). Parallel veins 36°25' 117°43' across bedding in tactitic Permian limestone and ore shoots along bedding fractures in Mississippian limestone. Hall and Mackevett, 1958. 51. Darwin. Replacement bodies 36°17' 117°36' near and along faults in tactitic Pennsylvanian limestone adjacent to granodiorite stock. Hall and Mackevett, 1958. 52. Modoc. Bedded replacement 36°16' 117°28' bodies along small faults in Carboniferous limestone. Hall and Mackevett, 1958; Norman and Stewart, 1951. 53. Panamint. Veins in early Pale- 36°06' 117°05' ozoic(?) limestone, schist, and slate. Murphy, 1930. 54. Carbonate (Queen of Sheba 36°00' 116°53' mine). Replacement bodies along bedding of Paleozoic(?) dolomitic limestone. Norman and Stewart, 1951. 55. Resting Springs (Tecopa). Re- 35°50' 116°06' placement bodies along fault in­ tersections in Cambrian dolo­ mite and limestone. Carlisle and others, 1954; Sampson, 1937. 56. Slate Range.Replacement bodies 35°49' 117°17' along bedding fissures in steeply-dipping Paleozoic(?) limestone. Norman and Stewart, 57. Cove. Byproduct of gold. Vein 35°44' 118°26' in shear zone along grano11

Index (cont'd.) CALIFORNIA (cont'd.) diorite-alaskite fault contact. Prout, 1940. 58. Amalie (Agua Caliente). Veins within quartz porphyry in grano­ diorite. Tucker and others, 1949. 59. Mojave. Veins along faults in Miocene dacite flows and plugs, and on contact between flows and underlying Upper Jurassic quartz monzonite. Tucker, 1935. 60. Randsburg. Intersecting vein systems in Precambrian bio­ tite schist, amphibole schist, and quartzite, in footwall of flat fault. Wright and others, 1953; Hulin, 1925. 61. Grapevine (Waterman mine). Vein along steeply-dipping con­ tact between rhyolite and over­ lying rhyolite tuff. Wright and others, 1953. 62. Calico. Veins along or near faults and disseminated de­ posits in shattered Miocene vol­ canic rocks and lake beds. Wright and others, 1953; Erwin and Gardner, 1940. 63. Clark Mountain (Ivanpah in part). Replacement bodies, in part localized by fractures near quartz monzonite sill, in Miss­ issippian limestone and De­ vonian dolomite; veins in De­ vonian dolomite, locally on bedd­ ing. Wright and others, 1953; Hewett, 1956. 64. Cima (Death Valley mine). Veins in quartz monzonite of Laramide age. Hewett, 1956. 65. Buckeye (Bagdad Chase mine). Byproduct of lode gold. Wright and others, 1953. 66. Lava Beds. Veins in Upper Jurassic(?) monzonite porphyry. Tucker and Sampson, 1940. 67. Dale (Monte Negro). Byproduct of lode gold. Tucker and Samp­ son, 1945; Wright and others, 68. Eagle Mi ountain. Vein along quartzite-diorite contact. Tuck­ er and Sampson, 1945. 69. Paymaster (Paymaster mine). Vein along fault(?) contact bet­ ween diorite and granite. Samp­ son and Tucker, 1942. 35°17' 118°27' 34°58' 118°14' 35°21' 117°38' 34°58' 117°02' 34°58' 116°52' 35°29' 115°34' 35°13' 115°28' 34°38' 116°10' 34°40' 116°25' 34°02' 115°41' 115°33' 33°12' 114°54' CALIFORNIA (cont'd.) 70. Cargo Muchacho. Byproduct of 32°53' 114°49' lode gold. Henshaw, 1942. 71. Silverado (Santa Rosa). Veins 33°45' 117°37' in syenite and porphyry. Merrill, 1919; Fairbanks, 1893. 72. Santa Catalina Island. Lodes in 33°21' 118°22' Jurassic hornblende schist and in andesite. Tucker, 1927. COLORADO 1. La Sal (Cashin mine). Veinlets 38°19' 108°57' in fissure zones along intersecting faults in Triassic or Jurassic sandstone. Emmons, 1906; Fischer, 1936. 2. Lone Cone (Dunton). Fissure 37°46' 108°06' veins in shale of Permian and Triassic ages. Bastin, 1923. 3. Rico (Pioneer). Replacement 37°42' 108°01' bodies along bedding and frac­ tures in Pennsylvanian lime­ stone; veins along fractures in sandstone and arkose; filling of breccia from solution of gypsum bed. Burbank and others, 1947; Ransome, 1901b; Cross andSpen­ cer, 1900. 4. La Plata (California). Veins and 370221 108°04' veinlet systems along breccia zones in Pennsylvanian, Permian, and Jurassic sandstones and ar­ koses and in Laramide porphyry stocks; replacement bodies in Jurassic limestone. Eckel, 1949. 5. Animas (Silverton). Lode veins, 37°48' 107°36' partly along dikes, in Miocene (?) extrusive and intrusive igneous rocks. Burbank, 1933. 6. Eureka. Lode veins in Miocene 37°54' 107°36' andesite and latite. Burbank and others, 1947. 7. Poughkeepsie, Mineral Point, and 37°57' 107°37' Upper Uncompahgre. Veins and lodes along faults and filling of breccia chimneys in Miocene extrusive and intrusive igneous rocks. Kelley, 1946. 8. Red Mountain. Filling of volcanic 37°54' 107°42' breccia pipes with replacement or veining of adjacent volcanic rocks of Miocene age. Burbank, 1941. 9. Ophir (Iron Springs) (including 37°52' 107050' Alta mine). Lode veins in Terti­ ary extrusive and intrusive ig­ neous rocks, and in conglomerate and sandstone of Permian and Eocene age. Burbank and others,

Index (contid.) COLORADO (cont'd.) 10. Sneffels and Telluride (Upper 37°57' 107°46' San Miguel). Lode veins, partly along dikes, in Miocene volcanic rocks. Burbank and others, 1947; Ransome, 1901a; Burbank, 1941. 11. Uncompahgre (Ouray). Veins 38°03' 107°40' and replacement bodies along fissures and bedding and within breccias in quartzites, sand­ stones, limestones, and shales ranging from Pennsylvanian to Cretaceous in age. Burbank, 12. Lake City (Galena, Lake). Veins 38°01' 107°22' in Miocene andesite, latite, and rhyolite, along fissures in cald­ era rift zone. Burbank and others, 1947; Irving and Ban­ croft, 1911. 13. Creede. Veins along faults in 37°52' 106°56' Miocene rhyolite. Emmons and Larsen, 1923; Larsen, 1929. 14. Summitville. Byproduct of gold. 37°26' 106°36' Replacement veins and pipes along fracture zones in Upper Tertiary quartz latite. Patton, 1917; Garrey, 1950. 15. Kerber Creek (Bonanza). Veins 38°19' 106°08' in Oligocene(?) andesite and latite. Burbank, 1932. 16. Monarch (Garfield). Replace- 38°32' 106°18' ment bodies, mostly adjacent to faults, in dominantly Ordovician limestone and dolomite. Dings and Robinson, 1957. 17. White Pine (Tomichi). Re- A8°32' 106°23' placement bodies within fault zones or along adjacent bedding in Ordovician and Mississippian limestone and dolomite. Dings and Robinson, 1957. 18. Chalk Creek (Mary Murphy 38°40' 106°21' mine). Lodes in quartz mon­ zonite of Tertiary age. Dings and Robinson, 1957. 19. Gold Brick. Replacement veins 38°37' 106°35' along faults in Precambrian gne­ iss and schist. Crawford and Worcester, 1916. 20. Quartz Creek. Replacement 380401 106°30' bodies adjacent to faults in Ordo­ vician and Carboniferous lime­ stones, veins in Precambrian gneissic granite. Dings and Robinson, 1957. 21. Tincup. Bedded replacement 38°43' 106°29' bodies and veins in Mississi­ ppian and Ordovician limestone COLORADO (cont'd.) and dolomite; fissure veins in Ordovician and Devonian quart­ zite and in quartz diorite por­ phyry (early(?) Tertiary). Dings and Robinson, 1957. 22. Dorchester-Taylor Park. Veins 38°57' 106°40' and replacement bodies in Carboniferous dolomite and limestone. Vanderwilt, 1947. 23. Elk Mountain (Keystone mine). 38°52' 107°03' Veins and breccia filling along faults in Cretaceous sandstone. Emmons and others, 1894. 24. Rock Creek. Replacement 39°04' 107°06' bodies along bedding or cross fractures in limestone beds of Devonian to Cretaceous age. Vanderwilt, 1937. 25. Roaring Fork (Aspen). Brec- 39°11' 106°49' cia filling and replacement bodies in shattered Carboniferous dolomite and limestone. Vanderwilt, 1935; Spurr, 1898; Knopf, 1926. 26. Brush Creek. Impregnation of 39°35' 106°44' Jurassic sandstone below shale and just above thrust fault. Gabelman, 1950. 27. Red Cliff (Gilman, Battle Moun39°32' 1060231 tain) (Eagle mine). Replacement pipes along intersecting joints or faults in Devonian and Missi­ ssippian limestones; replace­ ment deposits in bedding breccia in Cambrian quartzite. Tweto and Lovering, 1947. 28. Sugar Loaf-St. Kevin (Indepen39°17' 106°23' dent). Lodes within shear zones in Precambrian granite, schist and gneiss. Singewald, 1955. 29. Leadville (California). Replace39°14' 1060161 ment bodies along fissures and chiefly below porphyry sills or shale, in Ordovician and Mississippian limestones. Emmons and others, 1927. 30. Horseshoe-Sacramento (Hill- 39°13' 106°10' top mine). Replacement pipes at intersections of faults and fractures with favorable dolo­ mite beds in Devonian and Mississippian strata. Behre, 1953; Singewald and Butler, 1941. 31. Alma (Mosquito, Buckskin, Con- 39°18' 106°06' solidated Montgomery). Veins along faults in or adjoining lower Tertiary quartzite; replaceMent bodies within shattered zones in Ordovician and Mis­ sissippian limestone. Singe13

Index (cont'd.) COLORADO (cont'd.) COLORADO (cont'd.) 42. Caribou-Grand Island. Veins 39°59' 105°34' along faults in monzonite stock wald and Butler, 1933, 1941. of Laramide age and in Precam32. Upper Blue River. Replacement 39°23' 106°04' brian schist, gneiss andgranite. bodies adjacent to fractures Lovering and Goddard, 1950. cutting Devonian, Pennsylvanian 43. Ward. Byproduct of lode gold. 40°04' 105°30' and Permian limestone beds betLovering and Goddard, 1950. ween unfavorable rock types. Singewald, 1951. 44. Gold Hill (Sugar Loaf). Bypro- 40°03' 105°23' duct of gold. Veins and stock33. Kokomo (Tenmile. Replacement 39°25' 106°12' works along faults in Precampipes along fractures in Pennbrian granite. Lovering and sylvanian limestone beds betGoddard, 1950. ween unfavorable rock types. Koschmann and Wells, 1946. 45. Jamestown (Central). Veins 40°08' 105°23' along faults in Precambrian 34. Breckenridge. Veins along 9°29' 106°01' schist and granite; filling of faults in Eocene(?) monzonite breccia zones in lower Tertiporphyry and in Cretaceous ary granodiorite. Lovering and quartz monzonite porphyry. Goddard, 1950. Lovering, 1934. 46. Cripple Creek. Byproduct of 38°44' 105°08' 35. Montezuma (Snake River). Veins 39°35' 105°51' gold. Radiating steep sheeted partly along faults, in Precamveins in Tertiary volcanic plug brian gneiss and granite and in of latite-phonolite pyroclastic Eocene quartz monzonite. Lomaterial. Loughlin and Koschvering, 1935. mann, 1935. 36. Green Mountain (Big Four 39°53' 106°20' 47. Hardscrabble (Silver Cliff, 38°09' 105°27' mine). Byproduct of zinc. FracWestcliff). Veins and stockworks ture filling and replacement in lower Tertiary rhyolite and bodies in Cretaceous quartzite tuff; veins in Precambrian granand shale adjacent to porphyry ite and gneiss; interstitial fillstock. McCulloch and Huleatt, ing of rubble in chimney in Pre­ cambrian gneiss, granite, and 37. Argentine. Veins, partly along 39°39' 105°47' syenite. Emmons, 1896. faults, in Precambrian granite, 48. Rosita Hills. Veins along 38°07' 105°20' gneiss, and schist. Lovering, faults in lower Tertiary ande1935. site and trachyte and Precam38. Silver Plume-Georgetown (Gri39°42' 105°43' brian granite; interstitial fillffith). Veins along faults and ing of rubble in lower Tertiary locally following porphyry dikes volcanic neck in granite and in Precambrian granite, peggneiss. Emmons, 1896. matite, gneiss, and schist. IDAHO Lovering and Goddard, 1950. 1. Port Hill (Idaho Continental 48°56' 116053' 39. Central City-Idaho Springs (in- 39°45' 105°32' mine). Replacement bodies along cluding Trail Creek). Veins shear zones and fissures in Prealong faults and foliation in cambrian sericitic quartzite. Precambrian gneiss, pegmatite, Kirkham and Ellis, 1926. and schist (may follow porphyry dikes of Laramide age); bypro2. Talache (Pend Oreille in part) 48°08' 116°29' duct of gold in pyritic stockwork (Armstead mine). Fissure veins in gneiss. Lovering and Goddin Precambrian argillite. Sampard, 1950. son, 1928. 40. Lawson-Dumont (Montana). 39°46' 105°38' 3. Clark Fork. Replacement veins 48°10' 116010' Veins in Precambrian gneiss, along shear zones in Precambrian granite, and pegmatite. Loverargillite, quartzite, and limeing and Goddard, 1950. stone. Anderson, 1947a. 41. Alice (Alice mine). Byproduct 39°49' 105°39' 4. Lake View. Ore shoots in breccia 47°54' 116°27' of gold and copper. Gossan and along fault fissures in Precam­ enriched sulfide zone of pyritic brian quartzite and argillite. stockwork in quartz monzonite Sampson, 1928. porphyry stock of Laramide age. 5. West Coeur d'Alene. Composite 47°30' 116°04' Lovering and Goddard, 1950. replacement veins along shear

Index (cont'd.) IDAHO (cont'd.) IDAHO (cont'd.) 1947d. zones in Precambrian sericitic 18. Banner. Fissure veins along 44°02' 115°32' quartzite. Ransome and Calkins, a shear zone within Cretaceous 1908; Umpleby and Jones, 1923; (?) granodiorite batholith. AndShenon and McConnel, 1939. erson and Rasor, 1923. 6. East. Coeur d'Alene. Composite 47°31' 115°50' 19. Atlanta (Middle Boise). Brec- 43°47' 115°06' replacement veins along shear cia filling of wide shear zones zones in Precambrian sericitic in quartz monzonite of Early quartzite. Ransome and Calkins, Cretaceous(?) age. Anderson, 1908; Umpleby and Jones, 1923. 7. Elk City. Byproduct of lode and 45°49' 115°24' 20. Rosetta (Little Smoky). Veins 43°36' 114°42' placer gold. Shenon and Reed, and replacement bodies along crushed zones in Pennsylvanian (?) limestone. Ross, 1930; Urn8. Florence. Byproduct of lode and 45°31' 116°02' pleby, 1914. placer gold. Reed, 1939. 21, Vienna. Veins along crushed 43°49' 114°50' 9. Marshall Lake. Byproduct of lode 45°25' 115°52' zone, with some replaceand placer gold. Reed, 1937; Ross, ment, in quartz monzonite of Cretaceous(?) age. Ross, 10. Warren. Byproduct of placer and 45°16' 115041' lode gold. Reed, 1937. 22. East Fork. Replacement veins 44°00' 114°39' 11. Yellow Pine. Byproduct of anti44°55' 115°20' and lodes along conjugate frac­ mony and gold. Replacement tures in Mississippian argillite, bodies along wide fault zone in and along shear zones in CreLower Cretaceous(?) quartz taceous(?) quartz diorite stock. monzonite batholith. Cooper, Ross, 1937. 23. Boulder Creek (Livingston 44°08' 114°36' 12. Seafoam. Replacement bodies in 44°35' 115°04' mine). Replacement lodes along Cambrian(?) dolomitic limeshear zones in Mississippian stone occurring as xenolith in siliceous argillite and in Lower Cretaceous quartz monshattered rhyolite porphyry zonite batholith; replacement dikes of Mesozoic or Tertiary bodies in shear zones in the age. Kiilsgaard, 1949. batholith. Treves and Melear, 24. Yankee Fork. Breccia veins, 44°23' 114°42' lodes, and stockworks in altered 13. Deadwood (Cascade). Replace44°28' 115°35' Oligocene andesite, latite, and ment bodies in vertical shear tuff. Anderson, 1949. zone in "granite." Campbell, 25. Bayhorse. Replacement bodies 44°21' 114°23' in Cambrian and Ordovician do14. .Mineral. Replacement veins 44°34' 117°05' lomite; lodes in argillite. Ross, along fractures in Permian(?) andesite and latite. Anderson 26. Blue Wing. Veins in Precam- 44°32' 113°41' and Wagner, 1952. brian quartzitic slates and 15. Pearl-Horseshoe Bend (West 43°51' 116°19' schists. Callaghan and LemView). Stringers and seams mon, 1941. along complex fissure zones in 27. Junction (Leadville mine). Re- 44°42' 113°18' Cretaceous(?) granodiorite bathplacement bodies adjacent to olith. Anderson, 1934. bedding fault in Paleozoic lime16. Quartzburg. Byproduct of gold. 43°57' 115°59' stone. Umpleby, 1913. Fissure and replacement lodes 28. Texas. Replacement bodies 44°28' 113°18' along shear zone within Cre­ along fissures and bedding in taceous(?) quartz monzonite Paleozoic limestone. Umpleby, batholith; placer gold. Anderson, 1947d. 29. Nicholia (Viola mine). Replace- 44°22' 112°59' 17. Grimes Pass (Pioneerville) 44°01' 1150491 ment bodies along fractures in (Comeback mine). Replacement Upper Ordovician or Devonian lodes along fissures or shear limestone. Anderson and Wagzones in Cretaceous(?) quartz ner, 1944. monzonite batholith or in Mio­ cene porphyry dikes. Anderson, 30. Birch Creek. Replacement 44°09' 112°50'

Index (cont'cl.) IDAHO (cont'd.) bodies along bedding in limestones of Ordovician, Devonian, and Pennsylvanian age. Anderson and Wagner, 1944. 31. Dome (Wilbert mine). Replace- 43°58' 113°01' ment bodies along fracture zones in Ordovician quartzitic dolomite. Ross, 1933; Anderson, 1947b. 32. Alder Creek. Replacement veins 43°54' 113°41' in tactitic Mississippian limestone or along its contact with quartz diorite stock, Ross, 1930. 33. Lava Creek. Fissure veins and 43°33' 1130371 replacement bodies within brecciated zones in Miocene(?) andesite and latite and in Mississippian limestone. Anderson, 1929; Anderson, 1947c. 34. Muldoon (Little Wood River) 43°3T 113°53' (Muldoon mine). Replacement bodies along faults in Carboniferous limestone, slate, and quartzite, and along contact with quartz diorite sill. Anderson and Wagner, 1946. 35. Warm Springs. Replacement 43°40' 114°17' lodes along shear zones in Mississippian argillite. Umpleby and others, 1930; Killsgaard, 1950. 36. Mineral Hill (Wood River). Fis43°29' 1140221 sure veins in Carboniferous cal­ careous shale bordering a mon­ zonitic batholith. Umpleby and others, 1930; Anderson and others, 1950. 37. DeLamar. Veins, breccia veins, 43°01' 116°49' and silicified shear zones in Miocene(?) rhyolite. Piper and Laney, 1926. 38. Silver City (Carson, in part). 43°01' 116°43' Veins, breccia veins, and silicified shear zones in Cretaceous(?) granodiorite and in Miocene(?) rhyolite and basalt. Piper and Laney, 1926. 39. Flint (Rising Star mine). Veins 42°55' 116°46' in Cretaceous(?) stock of granite to diorite. Piper and Laney, 1926. 40. South Mountain. Contact meta- 42°45' 116°56' morphic deposits and replacement veins along vertical fractures in limestone. Sorenson, ILLINOIS 1. Cave in Rock. Byproduct of lead 37°30' 88°12' ILLINOIS (cont'd.) and zinc. Lode veins and replacement bodies in fault blocks of Mississippian limestone. Oesterling, 1952; Currier and Hubbert, 1944. MICHIGAN 1. Michigan copper. Byproduct of 47°15' 88°30' copper. Native copper and silver in conglomerate and amygdaloidal lodes; fissure veins in lava flows of Keweenawan age. Butler and Burbank, 1929. 2. White Pine. Byproduct of cop- 46°45' 89°35' per. Disseminated ore in Pre­ cambrian shale, siltstone, and sandstone. White and Wright, 1954; Butler and Burbank, 1929. KENTUCKY 1. Western Kentucky. Byproduct of 37°15' 88°12' lead and zinc. Lode veins and replacement bodies in fault blocks of Mississippian limestone. Oesterling, 1952. MISSOURI 1. Flat River-Bonne Terre. By- 37°52' 90°33' product of lead. Bedded replacement bodies in Cambrian dolomite near buried Precambrian ridges. Tarr, 1936. 2. Fredericktown. Byproduct of 37°35' 90018' lead. Bedded replacement bodies in Cambrian sandy dolomite near buried Precambrian ridges. Winslow, 1894. MONTANA 1. Troy (Grouse Mountain) (Snow- 48°27' 115°59' storm mine). Replacement lodes in Mesozoic(?) metadiorite dikes that intrude Precambrian argillite. Gibson, 1948. 2. Libby. Replacement lodes along 48°13' 115°38' shear zones in Precambrian argillite. Gibson, 1948. 3. Hog Heaven. Replacement bodies 47°56' 114°34' in stockwork in porphyritic latite intrusive mass of late Tertiary age. Shenon and Taylor, 1936. 4. Eagle (Jack Waite mine). Re47°40' 115°44' placement veins along shears in Precambrian fine-grained quart­ zite and argillite. Hosterman, 5. Packer Creek (Last Chance, Sil- 47°28' 115°34' ver Cable mine). Replacement veins along faults and fractures in Precambrian argillite and quartzite. Wallace and Hosterman, 1956. 6. Keystone (Iron Mountain) (Iron 47°16' 114°54'

Index (cont'd.) MONTANA (cont'd.) MONTANA (cont'd.) 17. Polaris (Lost Cloud). Replace- 45°23' 113°05' ment bodies in Carboniferous Mountain, Nancy Lee mines). Relimestone near contact with placement veins parallel to foli­ quartz monzonite batholith. Wination in Precambrian quartzite chell, 1914. and argillite. 18. Argenta. Replacement bodies 45°18' 112°53' 7. Curlew (Curlew mine). Fissure 46°28' 114°10' along bedding and fissures in filling along fault contact between Cambrian, Devonian, and Missi­ granite (or Pleistocene gravel?) ssippian limestones; fissure and Precambrian(?) quartzite and veins in Precambrian shale and limestone. Sahinen, 1957. in quartz monzonite of Lara8. Garnet (First Chance). Veins 46°49' 113°21' mide(?) age. Shenon, 1931. in granodiorite stock of Lara19. Blue Wing. Replacement veins 45°12' 112°57' mide age, and along bedding in in Mississippian limestone and adjacent Precambrian and Camin granodiorite stock of Larabrian quartzite and schistose shale. Pardee, 1918. mide(?) age. Shenon, 1931. 9. Dunkleberg. Veins near axis of 46°31' 113°05' 20. Virginia City (Alder Gulch). By45°14' 111°58' anticline in rocks of Cretaceous product of lode and placer gold. age, and in dioritic and gabbroic Tansley and others, 1933. sills; replacement bodies in lime­ 21. Norris. Byproduct of gold. Veins 45°33' 111°42' stone. Pardee, 1917; Popoff, 1953. along intersections of fissures 10. Henderson (Black Pine) (Combi46°27' 113°22' in quartz monzonite batholith nation mine Black Pine mine). of Laramide(?) age and in adFissure vein along bedding in jacent Precambrian gneiss and Precambrian quartzite. Emschist. Tansley and others,1933. mons and Calkins, 1913. 22. Sheridan. Veins and replace- 45°28' 112°08' 11. Boulder and South Boulder. Fis- 46°24' 113°08' ment bodies along faults and sure veins in granite stock of bedding in Precambrian limeearly(?) Tertiary age, and in stone and marble. Tansley and adjacent Precambrian, Carboniothrs, 1933. ferous, and Mesozoic quartzites 23. Pony (Mineral Hill, South 450391 111°58' and impure limestones; replaceBoulder). Veins in Precambrian ment veins in limestone. Emgneiss and schist, and in aplite mons and Calkins, 1913. and quartz monzonite of Lara12. Philipsburg (Flint Creek). Re46°20' 113°16' mide(?) batholith. Tansley and placement bodies in Cambrian, others, 1933. Silurian, and Devonian lime­ 24. Tidal Wave (Twin Bridges). Fis- 45°35' 112°10' stones and shales; veins in sure veins in Precambrian granodiorite. Emmons and Calgneiss and Lower Tertiary(?) kins, 1913. quartz monzonite; replacement 13. Georgetown. Byproduct of gold. 46°12' 113°14' bodies along fissures and beddReplacement bodies and veins ing in Paleozoic limestone. Tanin Cambrian and Devonian limesley and others, 1933. Stone near granodiorite stocks. 25. Rochester (Rabbit). Veins in 45°37' 112°29' Emmons and Calkins, 1913. Precambrian schist and gneiss; 14. Blue-eyed Nellie mine. Re- 46°12' 113°07' replacement bodies along fracplacement bodies in Cambrian tures in Cambrian dolomitic limestone. Emmons and Callimestone. Sahinen, 1939. kins, 1913. 26. Melrose. Veins in Precambrian 45°42' 112°38' 15. Vipond. Ore shoots or pipes 45°43' 112°54' schist and argillite. Winchell, along fissures, and bedded re1914; Sahinen, 1950. placement bodies, in Paleozoic 27. Silver Star. Byproduct of gold. 45°41' 112°19' limestone on top of low antiContact metamorphic deposits cline. Taylor, 1942. in Paleozoic limestone; veins 16. Bryant (Hecla). Replacement 45°36' 112°55' in Precambrian schist and bodies along bedding in Camgneiss. Sahinen, 1939. brian dolomite on anticlinal 28. Renova (Cedar Hollow). Bypro- 45°47' 112°06' crests near contact with quartz duct of gold. Vein on fault nearmonzonite batholith. Karlstrom, ly along bedding of Cambrian 1948; Winchell, 1914. limestone. Tansley and others,

Index (cont'd.) MONTANA (cont'd.) MONTANA (cont'd.) age. Pardee and Schrader, 1933. 29. Whitehall (Cardwell). Veins in 45°53' 112°01' Precambrian calcareous shale, sandstone, and limestone, and in porphyry dikes. Winchell, 30. Butte(Summit Valley). Replace- 46°01' 112°32' ment lodes and veins in quartz monzonite of early Tertiary(?) age. Sales, 1914; Perry, 1932. 31. Oro Fino (Champion mine).Vein 46°14' 112°37' in quartz monzonite of Lara­ mide(?) age. Pardee and Sch­ rader, 1933. 32. Zosell (Emery). Replacement 46°22' 112036' veins along faults in Upper Cretaceous(?) andesite. Pardee and Schrader, 1933; Robertson,1953. 33. Elliston. Veins in andesite and 46°27' 112°24' quartz monzonite of Laramide age. Pardee and Schrader, 1933. 34. Rimini (Vaughn). Lodes in seri- 46°28' 112°15' citized quartz monzonite of Laramide(?) age. Pardee and Schrader, 1933. 35. Cataract (Basin) and Boulder 46°17' 112°13' (Comet, Gray Eagle, Hope-Katie mines). Replacement veins in quartz monzonite and aplite of Laramide age. Pardee andSchrader, 1933. 36. Wickes (Colorado). Veins in 46°22' 112°07' quartz latite and quartz monzonite of Laramide(?) age. Pardee and Schrader, 1933. 37. Elkhorn (Elkhorn mine). Re- 46°16' 111°57' placement bodies in Cambrian dolomite. Klepper and others, 38. Radersburg (Cedar Plains). 46°10' 111°42' Veins in andesite and latite of early Tertiary(?) age and in rocks of Paleozoic and Mesozoic ages. Pardee and Schrader,1933; Reed, 1951. 39. Park (Indian Creek) (Iron Mask 46°20' 111°39' mine). Veins in Lower Tertiary(?) andesite. Stone, 1911; Reed, 1951. 40. Beaver Creek (Winston). Veins 46°25' 111°42' in andesite and quartz monzonite of Laramide age. Pardee and Schrader, 1933; Reed, 1951. 41. Warm Spring. Veins in quartz 46°26' 111°53' monzonite of Laramide age. Pardee and Schrader, 1933. 42. Clancy (Lump Gulch). Lodes 46°28' 112°01' along fault zones in quartz monzonite and aplite of Laramide 43. Helena. Byproduct of gold. Con- 46°33' 112°04' tact metamorphic deposits in Mississippian limestone; veins along crushed zones in Lara­ mide quartz monzonite; and placers. Pardee and Schrader, 44. Scratch Gravel. Contact meta46°40' 112°05' morphic deposits in Precambrian limestone; veins in Pre­ cambrian shale, quartzite, and limestone, and in adjacent Lara­ mide quartz monzonite stock. Pardee and Schrader, 1933. 45. Marysville. Fissure veins in 46°45' 112°19' Precambrian hornstone bordering a quartz monzonite stock. Pardee and Schrader, 1933. 46. Stemple-Gould. Byproduct of 46°53' 112°28' gold. Veins in contact metamorphosed Precambrian argillite. Pardee and Schrader, 1933. 47. Heddleston (Mike Horse mine). 47°02' 112°22' Tabular breccia filling with some replacement in Precambrian argillite and quartzite and in igneous rocks. Pardee and Schrader, 1933. 48. Dry Gulch (Golden Messenger, 46°44' 111°43' Old Amber mines). Byproduct of lode gold. Pardee and Schrader, 1933; Mertie and others, 49. Castle Mountain. Replacement 46°27' 110°41' bodies along bedding and fractures in Mississippian and Cambrian limestone, partly along porphyry sills and dikes. Roby, 50. Neihart. Sheeted replacement 46°57' 110°44' veins in Precambrian gneiss and quartzite. Schafer, 1935; Robertson, 1951. 51. Barker (Hughesville) (Block P 47°05' 110°39' mine). Fissure vein in syenitic stock and at contact with Cambrian or Carboniferous limestone. Jackson and others, 1935; Weed, 1900; Spiroff, 1938. 52. North Moccasin (Kendall). By- 47°17' 109°29' product of lode gold. Blixt,1933. 53. Warm Springs. Byproduct of 47°10' 109°13' lode gold. Robertson, 1950. 54. Little Rockies. Byproduct of 47°54' 108°36' lode gold. Corry, 1933. 55. New World (Cooke City). Con- 45°02' 109°57' tact metamorphic deposits,veins and replacement bodies in Cam18

Index (cont'd.) MONTANA (cont'd.) brian and Ordovician limestone and dolomite. Lovering, 1930; Reed, 1950. NEVADA 1. Leadville (Leadville mine).Veins in diorite porphyry dike and in andesite a Tertiary age. Overton, 1947. 2. Sulphur. Veins and stringers in Tertiary rhyolite. Vanderburg, 1938a. 3. Rosebud. Replacement veins and stringers in Tertiary rhyolite. Vanderburg, 1936. 4. Antelope (Cedar). Replacement bodies in limestone; byproduct of copper in fissure in tourmalinized rhyolite. Vanderburg, 5. Seven Troughs. Veins along basalt dikes cutting Tertiary vol­ canic rocks. Vanderburg, 1936. 6. Trinity. Fissure veins in Cretaceous(?) granodiorite and in hornfelsed Jurassic slate. Van­ derburg, 1936. 7. Arabia. Fissure veins in Cretaceous(?) granodiorite and in xenoliths of Jurassic hornfels. Knopf, 1918b; Vanderburg, 1936. 8. Relief (Antelope Springs). Vein in Triassic limestone. Vander­ burg, 1936. 9. Rochester. Replacement veins and stringers in Triassic rhyo­ lite. Vanderburg, 1936. 10. Kennedy. Vein in Triassic volcanic and sedimentary rocks. Vanderburg, 1936. 11. Indian. Vanderbury, 1936. 12. Buena Vista (Unionville). Veins in Triassic rhyolite and limestone. Lincoln, 1923; Vanderburg, 1936. 13. Rye Patch (Echo). Fissure veins in Triassic limestone. Vander­ burg, 1936. 14. Star. Veins and bedding lenses in Triassic limestone. Vander­ burg, 1936. 15. Humboldt (Imlay). Veins in shale, quartzite, and limestone. Vanderburg, 1936. 16. Sierra (Dun Glen, Chafey).Veins 41°07' 40°54' 40°48' 40°41' 40°30' 40°20' 40°22' 40°12' 40°23' 40°25' 40°28' 40°28' 40°33' 40°35' 40043' 119°25' 118°39' 118°36' 118°32' 118°38.' 118°30' 118°24' 118°10' 118°11' 117°42' 118°09' 118009' 118°12' 118006' 118°13' 117°52' NEVADA (cont'd.) in silicified andesite near dia­ base dike, and fissure veins in limestone. Vanderburg, 1936. 17. Gold Run (Adelaide). Veins in 40°47' 117°31' limestone, quartzite, shale, and schist. Vanderburg, 1938a. 18. Winnemucca. Veins in Trias41°03' 117°42' sic calcareous slate. Vander­ burg, 1938a. 19. Barrett Springs. Veins in shale. 41008' 1170491 Vanderburg, 1938a. 20: Paradise Valley. Fissure veins 41°36' 117°27' in calcareous slate. Vanderburg, 1938a. 21. National. Veins in Tertiary vol41°50' 117°34' canic rocks. Vanderburg, 1938a. 22. Gold Circle (Midas). Replace41°14' 116°48' ment and fissure veins and lodes in rhyolite and along shat­ tered contact between rhyolite and andesite. Emmons, 1910; Granger and others, 1957. 23. Merrimac (Rip Van Winkle 41°07' 116°00' mine). Veins and bedding replacement bodies along faults bordering a graben in Mississippian shale and limestone. Granger and others, 1957. 24. Tuscarora. Stockworks and 41°18' 1160151 lodes in Tertiary rhyolite and andesite porphyry. Emmons, 1910; Nolan, 1936; Granger and others, 1957. 25. Good Hope. Lodes along shear 41°28' 116°30' zones in rhyolite flow breccia. Emmons, 1910; Granger and others, 1957. 26. Cornucopia. Lodes in Terti- 41°34' 116017' ary andesite. Granger and others, 1957. 27. Edgemont (Centennial). Fissure 41°41' 116°11' veins in Carboniferous(?) quartzite. Granger and others, 1957; Emmons, 1910. 28. Aura (Bull Run, Columbia). 41°49' 116°05' Lodes in limestone adjacent to granodiorite stock, and veins in the granodiorite. Granger and others, 1957; Emmons, 1910. 29. Mountain City (Cope, Van Duzer, 41°50' 115059' Rio Tinto). Fissure veins in granite and metamorphosed limestone; byproduct of copper in secondarily enriched ore. Emmons, 1910; Matson, 1947. 30. Jarbidge. Fissure veins in 41°51' 115°25' Tertiary rhyolite. Schrader, 1912, 1923; Granger and others,

Index (cont'd.) NEVADA (cont'd.) NEVADA (cont'd.) 31. Contact (Salmon River). Fissure 41°47' 114°45' veins, replacement bodies, and contact metamorphic deposits in Paleozoic limestone; veins in granodiorite near dikes of sye­ nite and lamprophyre. Schrader, 1912, 1935; Granger and others, 32. Delano (Cleveland and Delano 41°40' 114°15' mines). Replacement bodies along bedding in brecciated Paleozoic dolomite(?). Granger and others, 1957. 33. Spruce Mountain. Replacement 40°34' 114°50' bodies along bedding, fractures, and faults in Mississippian lime­ stone, partly at contact with porphyry dikes. Granger and others, 1957; Schrader, 1931. 34. Cherry Creek (Egan Canyon). 39°54' 114°55' Veins in Cambrian quartzite and in Cretaceous(?) quartz monzonite. Schrader, 1931. 35. Hunter. Replacement bodies in 39°37' 115°00' breccia along fault contact of Devonian dolomitic limestone with porphyry dikes. Hill, 1916. 36. Aurum. Replacement bodies 39°37' 114°32' along faults and bedding in Cambrian limestone. Hill, 1916. 37. Piermont. Veins in brecciated 39°30' 114°35' limestone at contact with por­ phyry and in slate. Lincoln, 1923., 38. Osceola. Lodes along fracture 39°04' 114°23' zones in Cambrian sedimentary rocks. Lincoln, 1923. 39. Taylor. Breccia filling and re39°05' 114°40' placement bodies in brecciated Ordovician(?) limestone. Lincoln, 1923. 40. Ward. Veins and replacement 39°05' 114°53' bodies along contact of quartz monzonite porphyry dikes with Pennsylvanian limestone. Hill, 41. Ely (Robinson). Replacement 39°15' 114°59' bodies along veins and bedding, and contact metamorphic de­ posits in Devonian and Carboni­ ferous limestones; byproduct of "porphyry" copper, dissemi­ nated in Jurassic(?) monzonite porphyry stocks. Spencer, 1917. 42. White Pine (Hamilton). Replace- 39°15' 115°30' ment bodies along veins and bedding in Ordovician dolomite; saddle reefs in Devonian lime­ stone below shale. Hague, 1870. 43. Newark. Vein in limestone. Lin39°32' 115°46' coin, 1923. 44. Eureka. Replacement bodies 39°30' 116°08' along fissures, partly along bedding, in Cambrian limestone. Sharp, 1948. 45. Mount Hope (Mt. Hope mine). 39°47' 116°10' Replacement bodies along bedding and faults in Pennsylvanian limestone roof pendant in alaskite stock. Matson, 1946. 46. Diamond. Fissure veins in sili39°52' 115°53' cified limestone. Vanderburg, 1938b. 47. Union. Replacement bodies in 40°03' 116°03' limestone. Vanderburg, 1938b. 48. Mineral Hill. Replacement 40°09' 116°06' bodies cutting across bedding in Paleozoic limestone. Vanderburg, 1938b. 49. Railroad (Bullion). Replace- 40°31' 116°00' ment bodies in near-vertical chimneys at fracture inter­ sections in Ordovician lime­ stone; some contact meta­ morphic deposits. Granger and others, 1957. 50. Safford. Veins in andesite. Van- 40'34' 116°20' derburg, 1938b. 51. Buckhorn. Veins along fault in 40°12' 116°28' kaolinized brecciated basalt and scoria. Vanderburg, 1938b. 52. ,Cortez. Replacement bodies in 40°09' 116°35' Ordovician(?) limestone, partly within sheeted zones parallel to porphyry dikes. Emmons, 1910; Vanderburg, 1938b. 53. Bullion. Fissure veins and 40°22' 116°44' sheeted lodes in Carboniferous limestone, quartzite, and shale and in andesite and granodiorite. Vanderburg, 1939; Emmons, 1910. 54. Hilltop. Veins in brecciated 40°26' 116°48' quartzite. Vanderburg, 1939. 55. Lewis. Veins in granodiorite 40°27' 116°52' and in Carboniferous quartzite, limestone, and slate, in part with replacement. Vanderburg, 56. Battle Mountain. Veins and re- 40°33' 117°07' placement bodies along faults in Carboniferous hornfels, conglomerate, and quartzite. Roberts, 1951. 57. Reese River (Austin). Veins in 39°28' 117°04' lower Tertiary(?) quartz monzonim and Paleozoic schistose

Index (cont'd.) NEVADA (cont'd.) NEVADA (cont'd.) quartzite. Vanderburg, 1939; Hill, 1915. 58. Kingston. Veins in limestone. 39°11' 117°08' Vanderburg, 1939. 59. Jackson. Fissure veins in ande39°08' 117°36' site. Kral, 1951. 60. Mammoth (Ellsworth). Veins in 38°58' 117°45' Tertiary rhyolite dikes cutting Triassic(?) metavolcanic rocks. Kral, 1951. 61. Bruner (Phonolite). Veins in 39°05' 117°48' brecciated Tertiary rhyolite and andesite. Kral, 1951. 62. Lodi (Illinois mine). Veins in 39°00' 117°53' Triassic limestone and limy shale at contact with intrusive granodiorite. Kral, 1951. 63. Quartz Mountain (San Rafael 39°03' 117°58' mine). Veins in Triassic limestone along contact with intrusive granodiorite porphyry. Kral, 1951. 64. Broken Hills. Veins and stock39°03' 118°02' works in andesite. Vanderburg, 65. Wonder. Veins in Tertiary rhyo- 39°2T 118°02' lite. Vanderburg, 1940. 66. Chalk Mountain (Chalk Mtn. 39°20' 118°07' mine). Replacement bodies along fissures and bedding planes in dolomitic limestone. Vanderburg, 1940. 67. Fairview. Fissure veins in 39°13' 118°10' Tertiary andesite. Vanderburg, 68. Sand Springs. Veins in schist, 39°19' 118°25' limestone, and andesite. Vanderburg, 1940. 69. Rawhide (Regent). Veins in 39°02' 118°25' rhyolite, dacite, and andesite. Vanderburg, 1937. 70. Holy Cross. Narrow veins in 39°05' 118°37' rhyolite and andesite. Vanderburg, 1940. 71. Talapoosa. Lodes along shear 39028' 119015' zones in Tertiary rhyolite. Stoddard and Carpenter, 1950. 72. Peavine. Veins and replace- 39035' 119°56' ment bodies in schist, in Cretaceous quartz monzonite, and in Tertiary andesite. Overton,. 73. Galena (Commonwealth mine). 39°21' 119°46' Veins in metamorphosed tuff and hornfels. Overton, 1947. 74. Flowery. Stringer network in 39°19' 119°36' andesite. Stoddard and Carpenter, 1950. 75. Comstock. Lodes and veins in 39°18' 119°38' Upper Tertiary igneous rocks ranging from diorite to andesite. Becker, 1882; Bastin, 1922; Gianella, 1936. 76. Silver City. Veins in Tertiary 39°14' 119°37' andesite and rhyolite. Stoddard and Carpenter, 1950; Gianella, 77. Como (Palmyra, Indian Springs). 39°10' 119°28' Veins in Tertiary volcanic rocks, chiefly andesite. Stoddard and Carpenter, 1950. 78. Yerington. Byproduct of copper. 38°59' 119°10' Disseminated deposits in quartz monzonite; contact metamorphic deposits in bordering limestone. Stoddard and Carpenter, 1950. 79. Wilson (Pine Grove, Rockland, 38°40' 119°07' Cambridge). Stringers and lenses along crushed zones in quartz monzonite. Stoddard and Carpenter, 1950; Hill, 1915. 80. Aurora (Esmeralda). Veins 38°17' 118°52' along fissures in Tertiary latite and andesite. Vanderburg, 81. Hawthorne. Vein along or near 38°28' 118°40' contact of granodiorite with Mesozoic limestone. Hill, 1915; Vanderburg, 1937. 82. Rand (Bovard). Breccia veins in 38°48' 118°24' Tertiary rhyolite and replacement veins in latite. Vanderburg, 83. Garfield. Veins in limestone 38°28' 118°20' and volcanic rocks. Vanderburg, 84. Santa Fe (Luning). Contact 38°32' 118°06' metamorphic deposits and re­ placement bodies in Triassic(?) limestones; veins in altered quartz monzonite. Vanderburg, 1937; Hill, 1915; Clark, 1922. 85. Silver Star (Gold Range, Mina, 38°20' 118°11' Douglas). Veins in Triassic conglomerates and Tertiary volcanic rocks. Vanderburg, 1937; Hill, 1915; Kerr, 1936. 86. Marietta (Black Mountain). Re- 38°17' 118°22' placement lodes in Triassic(?) andesite tuff, quartzite, conglomerate, and limestone. Vanderburg, 1937; Hill, 1915.

Index (cont'd.) NEVADA (cont'd.) NEVADA (cont'd.) 100. Klondyke. Veins in Cambrian 37054' 117°13' 87. Buena Vista (Oneota). Veins in 370551 118°19' extrusive and intrusive igneous rocks and in adjacent hornfels and marble. Vanderburg, 1937. 88. Candelaria (Columbus). Veins 38009' 118°05' in Ordovician(?) argillites and felsites. Knopf, 1922; Page,1959; Vanderburg, 1937. 89. Bell (Simon, Cedar Mountains) 38°34' 117°52' (Simon mine). Replacement bodies in Triassic limestone along sides of alaskite porphyry dike. Vanderburg, 1937; Knopf, 1921a. 90. Union (Grantsville, Berlin). 38°53' 117°35' Replacement bodies in Triassic limestone; veins in Permian(?) meta-andesite, Triassic slate, conglomerate and limestone, and Tertiary andesite. Kral, 1951; Ferguson and Muller, 1949. 91. Twin River (Milieu). Vein in 38°55' 117°16' slate. Kral, 1951. 92. Jefferson Canyon. Veins in 38°44' 117°01' Tertiary rhyolite and along contact with Ordovician slate. Lincoln, 1923. 93. Round Mountain. Byproduct of 38°41' 117°04' gold. Fissure veins in Tertiary rhyolite. Kral, 1951. 94. Belmont. Veins and lenses in 38037' 116°56' Ordovician limestone and shale near contact with granite intrusive. Kral, 1951. 95. Manhattan. Byproduct of gold. 38°33' 117°03' Veins, lodes, and stockworks in Paleozoic schists and limestones and in Tertiary volcanic rocks. Kral, 1951; Ferguson, 96. San Antone. Veins in Permian 38°15' 117°14' volcanic rocks and in Ordovician limestone. Kral, 1951. 97. Tonopah. Replacement veins in 38°05' 117°14' Tertiary andesite and rhyolite. Kral, 1951; Hewett and others, 1936; Nolan, 1935b. 98. Divide (Gold Mountain). Veins 38°01' 117°12' along shear zones in upper Tertiary pyroclastic rocks. Knopf, 1921b; Hewett and others, 99. Lone Mountain. Replacement 37°57' 117°25' bodies in Cambrian limestone along contact with porphyry dike or with granite intrusive. Ball, sedimentary rocks. Lincoln, 1923, Spurr, 1906. 101. Silver Peak (Red Mountain). 37°46' 117°36' Veins in Paleozoic sedimentary rocks. Lincoln, 1923. 102. Montezuma. Veins and re- 37°43' 117°23' placement bodies in Cambrian limestone near contact with quartz monzonite. Lincoln, 103. Goldfield. Byproduct of gold. 37°42' 117°15' Replacement bodies in Tertiary dacite and other volcanic rocks. Lincoln, 1923; Ransome, 1909a; Searles, 1948. 104. Lida. Veins and replacement 37°27' 117°33' bodies in Cambrian limestones. Lincoln, 1923. 105. Hornsilver. Veins in Paleozoic 37°22' 117°18' sediments near borders of granite intrusives. Ransome, 1909b; Hewett and others,1936. 106. Bullfrog. Veins and lodes along 36°53' 116°53' faults in Tertiary rhyolite. Kral, 1951. 107. Silverbow. Veins in rhyolite. 37053' 116°28' Kral, 1951; Hewett and others, 108. Reveille. Veins and stringers 38°01' 116°09' in brecciated Paleozoic limestone. Kral, 1951. 109. Bellehelen. Fissure veins in 38°05' 116°28' rhyolite. Kral, 1951. 110. Tybo. Replacement bodies 38°22' 116°24' along a fault in quartz latite porphyry dikes that intrude Cambrian and Ordovician limestones. Ferguson, 1933; Kral, 111. Morey. Veins in quartz latite. 38°40' 116°15' Kral, 1951. 112. Tempiute. Veins in lower 37°39' 115037' Paleozoic limestone. Hewett and others, 1936. 113. Groom (Groom mine).Replace- 37°20' I15°46' ment bodies along bedding and fissures in Cambrian limestone. Humphrey, 1945. 114. Bristol (Jackrabbit). Replace- 38°05' 114°36' ment bodies along intersections of fissures in Cambrian limestone. Westgate and Knopf, 115. Pioche. Replacement vein and 37°56' 114°29' bedded deposits along fissures in Cambrian limestone; veins

Index (cont'd.) NEVADA (cont'd.) in quartzite. Westgate and Knopf, 1932. NEW MEXICO (cont'd.) Pennsylvanian limestone. Harley, 1934. 8. Hermosa (Palomas). Irregular 33°10' 107°43' 116. Comet. Bedded replacement 37°53' 114°37' bodies in Cambrian limestone; veins in quartzite. Westgate and Knopf, 1932. 117. Ferguson (Delamar). Disseminated ore and veinlets in shatt­ 37°24' 114°49' ered Paleozoic quartzite. He­ wett and others, 1936. 118. Yellow Pine (Goodsprings). Replacement bodies along frac­ tures or folds in Mississippian dolomite. Albritton and others, 1954; Hewett, 1931a, 35°52' 115°31' 119. Eldorado. Fissure veins in 35°40' 114°50' Precambrian gneiss and schist and in quartz monzonite. Lin­ coln, 1923. 120. Searchlight. Breccia veins in metamorphosed lower Terti­ ary(?) andesite porphyry, in older volcanic rocks, and in Precambrian gneiss. Calla­ ghan, 1939. 35°27' 114°55' NEW HAMPSHIRE 1. Milan. Replacement lenses along schistosity in siliceous schist. Emmons, 1909. 44°34' 71015' NEW MEXICO 1. Cochiti. Veins and replacement bodies along fractures in mon­ zonite. Anderson, 1957. 35°52' 106°27' 2. Willow Creek (Pecos) (Pecos mine). Replacement lenses in shear zone in Precambrian mi­ 35046' 1050401 caceous diorite. Krieger, 1932; Harley, 1940. 3. New Placers. Replacement pipe at intersection of fractured zone 35°15' 106°12' with Pennsylvanian limestone bed; byproduct of copper-gold in contact metamorphic deposits. Lindgren and others, 1910. 4. Magdalena. Replacement bodies in Mississippian limestone, mostly along crests of low folds. Loughlin and Koschmann, 1942. 34°05.' 107°12' 5. Socorro Peak. Narrow veins in 34°04' 106°58' rhyolite and trachyte and assoc­ iated tuffs and breccias. Ander­ son, 1957. 6. Black Range. Fissure veins in Tertiary andesite. Harley, 1934. 33°27' 107°43' 7. Apache (Chloride). Replacement veins in Tertiary andesite and 107°45' replacement bodies along a faulted gentle anticline in Pennsylvanian limestone. Harley, 1934. 9. Kingston. Replacement bodies 32°55' 107°43' along fractures on axes of anticlines in Silurian limestone. Harley, 1934. 10. Lake Valley. Replacement 32°44' 107°34' bodies in Mississippian limestone. Harley, 1934; Jicha,1954. 11. Cook's Peak. Replacement 32°33' 107°43' bodies on broad anticlinal arches in Silurian limestone. Anderson, 1957; Jicha, 1954. 12. Swartz (Carpenter). Replace- 32°52' 107°48' ment bodies along bedding, shear zones, and fractures in Ordovician limestone. Anderson, 13. Georgetown. Replacement 32°51' 108°01' bodies in Silurian limestone below Devonian shale near granite porphyry dikes. Paige, 1916. 14. Central (Hanover). Replace- 32°47' 108°06' ment veins on faulted contact between porphyry dikes and Car­ boniferous limestone, or in the dikes; contact metamorphic de­ posits; byproduct of copper in "porphyry" copper deposits of Laramide age. Anderson, 1957; Lasky, 1936; Schmitt, 1935, 15. Pinos Altos. Replacement 32°52' 108°14' bodies along fractures in Penn­ sylvanian limestone; veins across contact between grano­ diorite and diorite porphyry of Late Cretaceous(?) age. Ander­ son, 1957; Paige, 1911. 16. Chloride Flat. Stringers and 32°47' 108°18' pockets along joints and bedding in Silurian limestone associated with porphyry dikes. Anderson, 1957. 17. Fleming. Irregular pockets in 32°46' 108°25' Cretaceous quartzite. Anderson, 18. Burro Mountains (Tyrone). By- 32°39' 108°28' product of copper. Disseminated ore, secondarily enriched, in highly fractured quartz mon­ zonite porphyry and in adjacent Precambrian granite. Ander­ son, 1957. 19. Black Hawk. Veins associated 32°42' 108°33'

Index (cont'd.) NEW MEXICO (cont'd.) with dikes of diorite porphyry in Precambrian gneiss. Ander­ son, 1957. 20. Mogollon. Veins along faults in 33°23' 108°49' Tertiary volcanic rocks. Anderson, 1957. 21. Steeple Rock. Lode veins in 32°51' 108°58' Tertiary extrusive and intrusive rocks. Lindgren and others, 1910; Anderson, 1957. 22. San Simon. Replacement bodies 32009' 109°00' near granite porphyry dikes in Precambrian(?) limestone. And­ erson, 1957. 23. Lordsburg. Veins along faults 32°18' 108°46' in granodiorite stock of Lara­ mide age. Lasky, 1938. 24. Hachita (Eureka). Veins and 31°55' 108°26' replacement bodies commonly along igneous dikes and sills in Cretaceous limestone. Lasky, 25. Victorio. Replacement bodies 32°10' 108°06' in Ordovician and Silurian lime­ stones. Anderson, 1957. 26. Organ. Replacement bodies 32°26' 106°36' along fracture zones or adjacent to porphyry sheets in Ordovician and Silurian dolomite; contact metamorphic deposits in Car­ boniferous limestone; veins in lower Tertiary(?) quartz mon­ zonite. Dunham, 1935. NEW YORK 1. Balmat- Edwards. Byproduct of 44018' 75°20' lead-zinc. Replacement bodies along channels of microbreccias in Precambrian limestone. Brown, 1936, 1947. NORTH CAROLINA 1. Ore Knob. Fissure veins ingran- 36°24' 81°18' ite gneiss. Ballard and Clayton, 1948; Ross, 1935. 2. Silver Hill. Replacement bodies 35043' 80°14' and disseminated ore in volcanic rocks. Pardee and Park, 1948. 3. Union Copper. Massive sulfide 35°31' 80°22' and gold-quartz lodes in belt of silicified chlorite-sericite schist. Pardee and Park, 1948. OREGON 1. Riddle. Byproduct of copper. 42°52' 123°23' Replacement bodies along schistosity in highly foliated Jurassic schist. Shenon, 1933. 2. Bohemia. Veins and replacement 43°35' 122°38' OREGON (cont'd.) bodies along breccia zones in extrusive and intrusive volcanic rocks of Miocene(?) age. Calla­ ghan and Buddington, 1938. 3. Ashwood (Trout Creek) (Oregon 44°44' 120040' King mine). Lode along brec­ ciated zones in Miocene(?) ande­ site. Parks and Swartley, 1916. 4. Granite. Byproduct of gold. Veins 44°52' 118°23' along brecciated shear zones in Permian(?) argillite and in Lara­ mide(?) granodiorite batholith. Pardee and Hewett, 1914; Hewett, 1931b; Koch, 1959. 5. Bourne. Byproduct of gold. Veins 44050' 118°12' in Paleozoic argillite. Swartley, 1914; Hewett, 1931b. 6. Greenhorn - Geiser. Byproduct 44°42' 118°25' of gold. Veins in Carboniferous argillite, Triassic greenstone, and Laramide(?) quartz diorite and serpentine. Swartley, 1914; Lindgren, 1901. 7. Rock Creek. Byproduct of gold. 44°52' 118°05' Veins in Paleozoic argillite and Mesozoic granodiorite. Swartley, 1914; Hewett, 1931b. 8. Cornucopia. Byproduct of gold. 45°01' 117°12' Veins in granodiorite, schist, and greenstone. Swartley, 1914; Goodspeed, 1939. PENNSYLVANIA 1. Cornwall. Byproduct of copper. 40°16' 76°24' Contact metasomatic bodies in Cambrian limestone near diabase dike. Callahan and Newhouse, 1929; Spencer, 1908. SOUTH DAKOTA 1. Bald Mountain (Bald Mountain 44°20' 103°50' mine). Byproduct of gold. Bedd­ ed replacement bodies along fractures in Cambrian dolomitic quartzite and sandy dolomite. Connolly, 1927; Connolly and O'Harra, 1929. 2. Whitewood (Lead) (Homestake, 44°22' 103°45' Belle Eldridge mines). Bypro­ duct of gold; lenticular replace­ ment bodies in highly altered Precambrian dolomite. Bypro­ duct of lead-zinc; bedded replace­ ment bodies along joint zones in Cambrian dolomite above por­ phyry sill or basal quartzite. Paige, 1924; Schwartz, 1937; Dav­ is, 1948; Connolly and O'Harra, 3. Galena (Bear Butte). Bedded re- 44°20' 103°38' placement bodies along fractures in Cambrian dolomitic quartzite

Index (cont'd.) SOUTH DAKOTA (cont'd.), and sandy dolomite. Connolly and O'Harra, 1929. TENNESSEE 1. Ducktown. Byproduct of copper. 35°02' 84°23' Replacement bodies in Cam­ brian(?) schist and graywacke. Emmons, 1932; Ross, 1935. TEXAS 1. Allamoore. Veins in Precam- 31°10' 104°55' brian sandstone and in crushed Precambrian limestone,phyllite, 4 and volcanic rocks along thrust fault. King and Flawn, 1953. 2. Van Horn Mountain. Disemi- 30055' 104°55' nated ore in Permian sandstone adjacent to bedding plane thrust fault. Sellards and Baker, 1934. 3. Shafter. Replacement bodies 29°48' 104°20' along fracture zones and thrust faults in Permian limestone. Ross, 1943. UTAH 1. Ashbrook (Vipont mine). Bedd- 41°59' 113°51' ing repla cement lenses and stockworks along small linear crenulations in Carboniferous(?) and Cambrian(?) limestone. Peterson, 1942. 2. Lucin. Replacement bodies ad- 41°15' 114°00' jacent to fissures in Carboniferous limestone. Butler and others, 1920. 3. Gold Hill (Clifton). Replacement 40°10' 113°50' bodies along fractures in Cambrian and Carboniferous limestones and dolomites; veins along faults in Tertiary quartz monzonite. Nolan, 1935a. 4. Rush Valley (Stockton). Bedded 40°28' 112°20' replacement bodies along fissures in Pennsylvanian limestone beds between quartzite beds. Gilluly, 1932. 5. Bingham (West Mountain). Bedd- 40°31' 112°09' ed replacement bodies along faults in Pennsylvanian limestone beds between quartzite beds; by­ product of copper in "porphyry" copper deposits in Tertiary quartz monzonite. Hunt and Pea­ cock, 1948; Boutwell, 1905. 6. Ophir. Bedded replacement 40°22' 112°15' bodies, pipes, and veins along fissures in Cambrian, Devonian, and Mississippian limestone, do­ lomite, and hornfels. Gilluly,1932. 7. Camp Floyd (Mercur). Bedded 40°19' 112°13' UTAH (cont'd.) replacement bodies and replacement veins in Mississippian limestone. Gilluly, 1932. 8. Little Cottonwood and Big Cotton- 40°36' 1110381 wood. Bedded replacement bodies, pipes, and fault breccia filling along crosscutting fissures in Cambrian, Devonian, and Missi-­ ssippian limestones and dolo­ mites; veins in Precambrian and Cambrian quartzite and shale. Calkins and Butler, 1943. 9. Park City. Bedded replacement 40°37' 111°31' and lode deposits along fissures in Pennsylvanian, Permian, and Triassic limestone; lode deposits in Pennsylvanian quartzite and in Upper Cretaceous(?) diorite porphyry. Boutwell, 1912, 1933. 10. American Fork. Bedded re- 40°32' 111°37' placement bodies in Cambrian limestone; fissure veins inPre­ cambrian and Cambrian quart­ zite. Calkins and Butler, 1943. 11. Carbonate (Dyer mine). Bypro- 40°44' 109°34' duct of copper. Replacement bodies in Mississippian(?)limestone. Butler and others, 1920. 12. Tintic. Replacement bodies 39°57' 112°05' along fractures in Cambrian, Ordovician, and Mississippian limestone and dolomite; veins in Tertiary igneous rocks. Lind­ gren and Loughlin, 1919; Bil­ lingsley and Crane, 1933. 13. West Tintic. Replacement 39°51' 112°25' bodies along fissures in Paleozoic dolomite and limestone. Butler and others, 1920; Stringham, 1942. .14. Dugway. Veins with local re- 39°59' 113°12' placement along faults in Cambrian and Mississippian quartzite, limestone, and dolomite. Butler and others, 1920. 15. Fish Spring.Replacement bodies 39°51' 113°27' along fissures and along wall of porphyry dike in Ordovician(?) and Silurian(?) limestone. Butler and others, 1920. 16. Stateline. Veins in Tertiary 38°05' 114°00' rhyolite and interbedded tuff. Butler and others, 1920. 17. San Francisco and Preuss (Horn 38°28' 113°17' Silver, Cactus mines). Replace­ ment veins along faults in Terti­ ary quartz latite or at its con­ tact with Cambrian(?) limestone; breccia pipe filling along fault in Tertiary quartz monzonite. But­ ler and others, 1920.

Index (cont'd.) UTAH (cont rd.) 18. Rocky (Old Hickory mine). By38°27' 113°04' product of copper. Contact meta­ morphic deposits in Triassic limestone. Butler, 1913. 19. Star. Replacement bodies, in38°22' 113°08' cluding pipes, along fissures in Silurian(?), Mississippian(?), and Triassic limestone. Butler and others, 1920. 20. Bradshaw (Cave mine).Replace38°18' 112°55' ment bodies adjacent to fissures and along bedding in Carboni­ ferous limestone. Butler and others, 1920. 21. Gold Mountain. Fissure veins 38°30' 112°24' along faults in middle(?) Terti­ ary dacite. Butler and others, 22. Ohio and Mount Baldy. Bedded 38°24' 112°18' replacement bodies in Jurassic limestone; veins along faults in Jurassic quartzite and Tertiary dacite. Butler and others, 1920. 23. Silver Reed (Harrisburg, Leeds), 37°15' 113°22' Disseminated deposits in Triassic sandstone associated with plant remains. Procter, 1953. 24. Tutsagubet. Replacement bodies 37°04' 113°48' along and adjacent to fissures in Pennsylvanian limestone. Butler and others, 1920. VERMONT 1. Vermont copper. Byproduct of 43°55' 72°19' copper. Massive and disseminated replacement bodies in Ordovician(?) schists. Buerger, 1935; McKinstry and Mikkola, VIRGINIA 1. Valzinco-Mineral. Veins along 38°06' 77°51' fissures and faults in Precam­ brian and Cambrian schists. Grosh, 1949. 2. Virgilina. Byproduct of copper. 36°32' 78°40' Fissure veins in lower Paleozoic gneisses and in Triassic sandstones and igneous rocks. Laney, 3. Austinville-Ivanhoe. Byproduct 36°51' 80°57' of zinc-lead. Ore along limb of anticline in brecciated Cambrian dolomite. Currier, 1935; Watson, WASHINGTON WASHINGTON (cont'd.) 2. Ruby - Conconully. Veins near 48°30' 119°44' and along border of granite batho­ lith of Laramide(?) age, and in adjacent schists. Patty, 1921. 3. Chelan Lake (Holden mine). By- 48°12' 120°47' product of copper. Pyritic re­ placement bodies along shear zone in amphibolite schist. Youngberg and Wilson, 1952. 4. Wenatchee (Lovitt mine). By- 47°18' 120°16' product of gold. Fissure veins in Eocene sandstone, shale, and conglomerate. Lovitt and Skerl, 5. Nespelem (Moses). Replacement 48°09' 119°01' lode along shear zone in granite batholith of Laramide(?) age. Patty, 1921. 6. Republic. Fissure veins, brec- 48°38' 118°43' cia ores, and disseminated deposits in Tertiary latite and andesite flows. Umpleby, 1910; Bancroft, 1914; Wright, 1947. 7. Deertrail (Cedar Canyon). Veins 48°02' 118°05' in fissures or shear zones along bedding in Cambrian(?) argillite and limestone. Weaver, 1920. 8. Springdale (Cleveland mine). 48°07' 118°01' Replacement veins along bedding fractures in dolomitic limestone and argillite of Paleozoic age. Jenkins, 1924. 9. Chewelah. Byproduct of copper. 48°19' 117°40' Veins along shear zones in Paleozoic(?) schist and argillite. Howard, 1925; Weaver, 1920. 10. Colville (Old Dominion mine). 48°33' 117°47' Replacement bodies along lowdipping fractures in Cambrian (?) limestone. Weaver, 1920; Howard, 1925; Jenkins, 1924. 11. Bossburg (Clugston Creek). Re- 48°44' 117°58' placement bodies along fractures and bedding in Cambrian (?) limestone and argillite. Jenkins, 1924; Weaver, 1920. 12. Northport. Replacement bodies 48°52' 117°43' along bedding and within shear zones in Cambrian(?) dolomite. Weaver, 1920; Jenkins, 1924. 13. Metaline. Byproduct of zinc- 48°52' 117°22' lead. Replacement bodies in Cambrian dolomite and brecciated dolomitic limestone. Park and Cannon, 1943. 1. Oroville - Nighthawk. Fissure 48°57' 119°40' veins in marginal areas of granodiorite of Laramide age. Patty,

References Cited Albers, J. P., 1953, Geology and ore deposits of the Afterthought mine, Shasta County, California: California Dept. Nat. Resources, Div. Mines Spec. Rept. 29. Albers, J. P., and Robertson, J. F., 1961, Geology and ore deposits of East Shasta copper-zinc district, Shasta County, California: U. S. Geol. Survey Prof. Paper 338. Albritton, C. C., Jr., Richards, Arthur, Brokaw, A. L., and Reinemund, J. A., 1954, Geologic controls of lead and zinc deposits in Goodsprings (Yellow Pine) district, Nevada: U. S. Geol. Survey Bull. Anderson, A. L., 1929, Geology and ore deposits of Lava Creek district, Idaho: Idaho Bur. Mines and Geology Pamph. 32. , 1934, Geology of the Pearl-Horseshoe Bend gold belt, Idaho: Idaho Bur. Mines and Geology Pamph. 41. , 1939, Geology and ore deposits of the Atlanta district, Elmore County, Idaho: Idaho Bur. Mines and Geology Pamph. 49. , 1947a, Geology of the lead-silver deposits of the Clark Fork district, Bonner County, Idaho: U. S. Geol. Survey Bull. 944-B. , 1947b, Structural control and wall-rock alteration at the Wilbert mineDomedistrict, Butte County, Idaho: Econ. Geology, v. 42, no. 4. , 1947c, Epithermal mineralization at the Last Chance and Hornsilver mines, Lava Creek district, Butte County, Idaho: Geol. Soc. American Bull. 58, no. 5. , 1947d, Geology and ore deposits of Boise Basin, Idaho: U. S. Geol. Survey Bull. 944 -C. , 1949, Silver -gold deposits of the Yankee Fork district, Custer County, Idaho: Idaho Bur. Mines and Geology Pamph. 83. Anderson, A. L., Kiilsgaard, T. H., and Fryklund, V. C., Jr., 1950, Detailed geology of certain areas in the Mineral Hill and Warm Springs mining districts, Blaine County, Idaho: Idaho Bur. Mines and Geology Pamph. 90. Anderson, A. L., and Rasor, A. C., 1923, Silver mineralization in the Banner district, Boise County, Idaho: Econ. Geology, v. 29, no. 4. Anderson, A. L., and Wagner, W. R. T., 1944, Lead­ zinc-copper deposits of the Birch Creek district, Clark and Lemhi Counties, Idaho: Idaho Bur. Mines and Geology Pamph. 70. , 1946, A geological reconnaissance in the Little Wood River (Muldoon) district, Blaine County, Idaho: Idaho Bur. Mines and Geology Pamph. 75. , 1952, Reconnaissance geology and ore deposits of the Mineral district, Washington County, Idaho: Idaho Bur. Mines and Geol. Pamph. Anderson, C. A., 1931, The geology of the Engels and Superior mines, Plumas County, Calif., with a note on the ore deposits of the Superior mine: California Univ. Dept. Geol. Sci. Bull., v. 20, no. 8. Anderson, C. A., and Creasey, S. C., 1958, Geology and ore deposits of the Jerome area, Yavapai County, Arizona: U. S. Geol. Survey Prof. Paper Anderson, C. A., Scholz, E. A., and Strobell, J. D., Jr., 1956, Geology and ore deposits of the Bagdad area, Yavapai County, Arizona: U. S. Geol. Survey Prof. Paper 278. Anderson, E. C., 1957, The metal resources of New Mexico and their economic features through 1954: New Mexico Bur. Mines and Mineral Resources Bull. 39. Aubury, L. E., 1910, Gold dredging in California: California State Mining Bur. Bull. 57. Averill, C. V., 1929, San Francisco field division, Napa County [Calif.]: State Mineralogist 25th Rept., Dept. Nat. Resources, Div. Mines, Mining in California, v. 25, no. 2. , 1933, Gold deposits of the Redding and Weaverville quadrangles [California]: California Jour. Mines and Geology, v. 29, nos. 1-2. , 1937, Mineral resources of Plumas County [California]: California Jour. Mines and Geology, v. 33, no. 2. , 1942, Mines and mineral resources of Sierra County [California]: California Jour. Mines and Geology, v. 38, no. 1. Ball, S. H., 1907, A geologic reconnaissance in south­ western Nevada and eastern California: U. S. Geol. Survey Bull. 308. Ballard, T. J., and Clayton, A. B., 1948, Investigation of the Ore Knob Copper Mine, Ashe County, North Carolina: U. S. Bur. Mines Rept. Inv. 4341. Bancroft, Howland, 1911, Reconnaissance of the ore deposits in northern Yuma County, Arizona: U. S. Geol. Survey Bull. 451. , 1914, The ore deposits of northeastern Washington, including a section on the Republic mining district, by Waldemar Lindgren and Ho­ ward Bancroft: U. S. Geol. Survey Bull. 550. Bastin, E. S., 1922, Bonanza ores of the Comstock lode, Virginia City, Nevada: U. S. Geol. Survey Bull. 735-C. , 1923, Silver enrichment in the San Juan Mountains, Colorado, in Contributions to Economic Geology, 1922, pt I, Metals and non-metals except fuels: U. S. Geol. Survey Bull. 735, p. 65-129. Bateman, P. C., 1956, Economic geology of the Bishop tungsten district, California: California Dept. Nat. Resources, Div. Mines Spec. Rept. 47. Becker, G. F., 1882, Geology of the Comstock lode and the Washoe district [Nevada]: U. S. Geol. Survey Mon. 3.

References Cited (cont'd.) Behre, C. H., Jr., 1953, Geology and ore deposits of the west slope of the Mosquito Range [Colorado]: U. S. Geol. Survey Prof. Paper 235. Billingsley, Paul, and Crane, G. W., 1933, Tintic mining district, in The Salt Lake region:Internat. Geol. Cong. 16th, Washington 1933, Guidebook 17. Blixt, J. E., 1933, Geology and gold deposits of the North Moccasin Mountains, Fergus County, Montana: Montana Bur. Mines and Geology, Mem. 8. Boutwell, J. M., 1905, Economic geology of the Bingham mining district, Utah: U. S. Geol. Survey Prof. Paper 38. , 1912, Geology and ore deposits of the Butler, B. S., Loughlin, G. F., Heikes, V. C., and others, 1920, The ore deposits of Utah: U. S. Geol. Survey Prof. Paper 111. Butler, B. S., Wilson, E. D., and Rasor, C. A., 1938, Geology and ore deposits of the Tombstone district, Arizona: Arizona Bur. Mines Bull. 143, Geol. Ser. 10. Calkins, F. C., and Butler, B. S., 1943, Geology and ore deposits of the Cottonwood-American Fork area, Utah: U. S. Geol. Survey Prof. Paper 201. Callaghan, Eugene, 1939, Geology of the Searchlight district, Clark County, Nevada: U. S. Geol. Survey Bull. 906-D. Callaghan, Eugene, and Buddington, A. F., 1938, Metalliferous mineral deposits of the Cascade Range in Oregon: U. S. Geol. Survey Bull. 893. Callaghan, Eugene, and Lemmon, D. M., 1941, Tungsten resources of the Blue Wing district, Lemhi County, Idaho: U. S. Geol. Survey Bull. 931-A. Callahan, W. H., and Newhouse, W. H., 1929, A study of the magnetite ore body at Cornwall, Pa.: Econ. Geology, v. 24, no. 4. Campbell, Stewart, 1930, Bunker Hill and Sullivan Mining and Concentrating Co.: Idaho Mining Industry 32d Ann. Rept. for 1930. Carlisle, Donald, Davis, D. L., Kildale, M. B., and Stewart, R. M., 1954, Base metal and iron deposits of southern California, in Jahns, R. H., ed., Geology of southern California: California Dept. Nat. Resources, Div. Mines Bull. 170, pt. 5, chap. 8. Carlson, D. W., 1955, Mines and mineral resources of Sacramento County, California: California Jour. Mines and Geology, v. 51, no. 2. Clark, C. W., 1922, Geology and ore deposits of the Santa Fe district, Mineral County, Nevada: California Univ., Dept. Geol. Sci. Bull., v. 14, no. 1. Clark, W. B., 1957, Gold, in Wright, L. A., ed., Mineral Commodities of California: California Div. Mines Bull. 176. Clark, W. B., and Carlson, D. W., 1956, Mines and mineral resources of El Dorado County, California: California Jour. Mines and Geology, v. 52, no. 4. Connolly, J. P., 1927, The Tertiary mineralization of the northern Black Hills: South Dakota School Mines Bull. 15. Connolly, J. P., and O'Harra, C. C., 1929, The mineral wealth of the Black Hills: South Dakota School Mines Bull. 16. Cooper, J. R., 1950, Johnson Camp area, Cochise County, Arizona, in Arizona zinc and lead deposits: Arizona Bur. Mines Bull. 156, Geol. Ser. 18, pt. 1, chap. 3. , 1951, Geology of the tungsten, anti- Park City district, Utah: U. S. Geol. Survey Prof. Paper 77. , 1933, Park City mining district: Internat. Geol. Cong., 16th, Washington 1933, Guidebook 17. Bowen, 0. E., Jr., and Gray, C. H., Jr., 1957, Mines and mineral deposits of Mariposa County, California: California Jour. Mines and Geology, v. 53, nos. 1-2. Boyle, A. C., Jr., 1915, The geology and ore deposits of the Bully Hill mining district, California: Am. Inst. Mining Engineers Trans. v. 48. Brown, J. S., 1936, Structure and primary mineralization of the zinc mine at Balmat, N. Y.: Econ. Geology, v. 31, no. 3. , 1947, Porosity and ore deposition at Edwards and Balmat, New York: Geol. Soc. American Bull., v. 58, no. 6. Buerger, V. W., 1935, The copper ores of Orange County, Vt.: Econ. Geology, v. 30, no. 4. Burbank, W. S., 1932, Geology and ore deposits of the Bonanza mining district, Colorado: U. S. Geol. Survey Prof. Paper 169. 1933, Vein systems of the Arrastre Basin and regional geologic structure in the Silverton and Telluride quadrangles, Colorado: Colorado Sci. Soc. Proc., v. 13, no. 5. , 1940, Structural control of ore de- position in the Uncompahgre district, Ouray County, Colorado: U. S. Geol. Survey Bull. 906-E. , 1941, Structural control of ore de- position in the Red Mountains, Sneffels, and Telluride. districts of the San Juan Mountains, Colorado: Colorado Sci. Soc. Proc., v. 14, no. 5. Burbank, W. S., Eckel, E. B., and Varnes, D. J., 1947, The San Juan region, in Mineral resources of Colorado: Colorado Mineral Resources Board [Pub.], pt. 2. Butler, B. S., 1913, Geology and ore deposits of the San Francisco and adjacent districts, Utah: U. S. Geol. Survey Prof. Paper 80. Butler, B. S., and Burbank, W. S., 1929, The copper deposits of Michigan: U. S. Geol. Survey Prof. Paper 144. mony, and gold deposits near Stibnite, Idaho: U. S. Geol. Survey Bull. 969-F.

References Cited (cont'd.) Corry, A. V., 1933, Some gold deposits of Broadwater, Beaverhead, Phillips and Fergus Counties, Mont.: Montana Bur. Mines and Geology Mem. Crawford, R. D., and Worcester, P. G., 1916, Geology and ore deposits of the Gold Brick district, Colorado: Colorado Geol. Survey Bull. 10. Creasey, S. C., 1950, Geology of the St. Anthony (Mammoth) area, Pinal County, Arizona, in Ari­ zona zinc and lead deposits: Arizona Bur. Mines Bull. 156, Geol. Ser. 18, pt. 1, chap. 6. Creasey, S. C., and Qukck, G. L., 1955, Copper deposits of part of Helvetia mining district, Pima County, Arizona: U. S. Geol. Survey Bull. 1027-F. Cross, C. W., and Spencer, A. C., 1900, Geology of the Rico Mountains, Colorado: U. S. Geol. Survey 21st Ann. Rept., pt. 2-A. Currier, L. W., 1935, Zinc and lead region of south­ western Virginia: Virginia Geol. Survey Bull. 43. Currier, L. W., and Hubbert, M. K., 1944, Geological and Geophysical survey of fluorspar areas in Hardin County, Illinois: U. S. Geol. Survey Bull. Davis, V. C., 1948, Belle Eldridge lead-zinc de­ posits, Lawrence County, S. Dak.: U. S. Bur. Mines Rept. Inv. 4215. Denton, W. C., and Clark, W. B., 1954, Mines and mineral resources of Amador County, Cali­ fornia: California Jour. Mines and Geology, v. 50, no. 1. Dings, M. G., 1951, The Wallapai mining district, Cerbat Mountains, Mohave County, Arizona: U. S. Geol. Survey Bull. 978-E. Dings, M. G., and Robinson, C. S., 1957, Geology and ore deposits of the Garfield quadrangle, Colorado: U. S. Geol. Survey Prof. Paper 289. Dunham, K. C., 1935, The geology of the Organ Mountains, with an account of the geology and

mineral resources of Dona Ana County, New -Mexico: New Mexico School Mines Bull. 11. Eckel, E. B., 1949, Geology and ore deposits of the La Plata district, Colorado: U. S. Geol. Survey Prof. Paper 219. Emmons, S. F., 1896, The mines of Custer County, Colorado: U. S. Geol. Survey 17th Ann. Rept., pt. 2-C. Emmons, S. F., Cross, C. W., and Eldridge, G. H., 1894, Description of the Elk Mountains [Colorado]: U. S. Geol. Survey Geol. Atlas, Folio 9. Emmons, S. F., Irving, J. D., .and Loughlin, G. F., 1927, GeolOgy and ore deposits of the Leadville mining district, Colorado: U. S. Geol. Survey Prof. Paper 148. Emmons, W. H., 1906, The Cashin Mine, Montrose County, Colorado, in Contributions to Economic Geology, 1905: U. S. Geol. Survey Bull. 285, p. 125-128. Emmons, W.H., 1909, Some regionally metamorphosed ore deposits and the so-called segregated veins: Econ. Geology, v. 4, no. 8. , 1910, A reconnaissance of some mining camps in Elko, Lander, and Eureka Counties, Nevada: U. S. Geol. Survey Bull. 408. , 1932, The Ducktown mining district, Tennessee, in Mining districts of the United States: Internat. Geol. Cong., 16th, Washington 1933, Guidebook 2. Emmons, W. H., and Calkins, F. C., 1913, Geology and ore deposits of the Philipsburg quadrangle, Montana: U. S. Geol. Survey Prof. Paper 78. Emmons, W. H., and Larson, E. S., 1923, Geology and ore deposits of the Creede district, Colo­ rado: U. S. Geol. Survey Bull. 718. Eric, J. H., 1948, Zinc-copper deposits of the Big Bend Mine, Butte County, California, in Copper in California: California Div. Mines Bull. 144, pt. 1. Eric, J. H., and Cox, M. W., 1948, Zinc deposits of the American Eagle-Blue Moon area, Mariposa County, California, in Copper in California: California Div. Mines Bull. 144, pt. 1. Eric, J. H., Stromquist, A. A., and Swinney, C. M., 1955, Geology and mineral deposits of the Angels Camp and Sonora quadrangles, Calaveras and Tuolumne Counties, California: California Div. Mines Spec. Rept. 41. Erwin, H. D., and Gardner, D. L., 1940, Notes on the geology of a portion of the Calico Mountains, San Bernardino County, Calif.: California Jour. Mines and Geology, v. 36, no. 3. Fairbanks, H. W., 1893, Geology of San Diego: also portions of Orange and San Bernardino Counties [California]: California Mining Bur., 11th Rept. State Mineralogist. Ferguson, H. G., 1914, Gold lodes of the Weaverville quadrangle, Calif.: U. S. Geol. Survey Bull. 540-A. , 1924, Geology and ore deposits of the Manhattan district, Nevada: U. S. Geol. Survey Bull. 723. , 1933, Geology of the Tybo district, Nevada: Nevada Univ. Bull., v. 27, no. 3. Ferguson, H. G., and Gannett, R. W., 1932, Gold quartz veins of the Alleghany district, Calif.: U. S. Geol. Survey Prof. Paper 172. Ferguson, H. G., and Muller, S. W., 1949, Structural geology of the Hawthorne and Tonopah quad­ rangles, Nevada: U. S. Geol. Survey Prof. Paper Fischer, R. P., 1936, Peculiar hydrothermal copperbearing veins of the northeastern Colorado Plateau: Econ. Geology, v. 31, no. 6. Fowler, G. M., 1938, Montana Mine, Ruby, in Some Arizona ore deposits: Arizona Bur. Mines Bull. 145, Geol. Ser. 12, pt. 2. Gabelman, J. W., 1950, Geology of the Fulford and Brush Creek mining districts, Eagle County,

References Cited (cont'd.) Colorado, in Mining Yearbook, 1950: Denver, Colorado, Colorado Mining Assoc., P. 50-52. Galbraith, F. W., and Loring, W. B., 1951, Swisshelm district, in Arizona zinc and lead deposits: Ariz­ ona Bur. Mines Bull. 158, Geol. Ser. 19, pt. 2, chap. 3. Garrey, G. H., 1950, Summitville mines, Rio Grande County, Colorado, in Mining Yearbook, 1950: Denver, Colorado, Colorado Mining Assoc., p. 129-130. Gianella, V. P., 1936, Geology of the Silver City district and the southern portion of the Comstock Lode, Nevada: Nevada Univ. Bull., v. 30, no. 9. Gibson, Russell, 1948, Geology and ore deposits of the Libby quadrangle, Montana: U. S: Geol. Survey Bull. 956. Gilluly, James, 1932, Geology and ore deposits.of the Stockton and Fairfield quadrangles, Utah: U. S. Geol. Survey Prof. Paper 173. , 1946, The Ajo mining district, Arizona: U. S. Geol. Survey Prof. Paper 209. Goodspeed, G. E., 1939, Geology of the Gold Quartz veins of Cornucopia [Oregon]: Am. Inst. Mining Metall. Engineers Tech. Pub. 1038. Granger, A. E., Bell, M. M., Simmons, G. C., and Lee, Florence, 1957, Geology and mineral resources of Elko County, Nevada: Nevada Bur. Mines Bull. 54. Graton, L. C., 1910, The occurrence of copper in Shasta County, Calif.: U. S. Geol. Survey Bull. 430-B. Grosh, W. A., 1949, Investigation of Valzinco leadzinc mine, Spotsylvania County, Virginia: U. S. Bur. Mines Rept. Inv. 4403. Hague, Arnold, 1870, Geology of the White Pine district[Nevada], in Mining industry (King volume): U. S. Geol. Explor. 40th Parallel, v. 3, chap. 6, sec. 4. Hall, W. E., and Mackevett, E. M., 1958, Economic geology of the Darwin quadrangle, Inyo County, California: California Div. Mines Spec. Rept. 51. Harley, G. T., 1934, The geology and ore deposits of Sierra County, New Mexico: New Mexico School Mines Bull. 10. , 1940, The geology and ore deposits of northeastern New Mexico (exclusive of Colfax County): New Mexico School Mines Bull. 15. Henshaw, P. C., 1942, Geology and mineral de­ posits of the Cargo Muchacho Mountains, Im­ perial County, Calif.: California Jour. Mines and Geology, v. 38, no. 2. Hewett, D. F., 1931a, Geology and ore deposits of the Goodsprings quadrangle, Nev.: U. S. Geol. Survey Prof. Paper 162. , 1931b, Zonal relations of the lodes of the Sumpter quadrangle [eastern Oregon]: Am. Inst. Mining Metall. Engineers Trans., 1931, p. 305-346. Hewett, ID.. F., 1956, Geology and mineral resources of the Ivanpah quadrangle, California and Nevada: U. S. Geol. Survey Prof. Paper 275. Hewett, D. F., Callaghan, Eugene, Moore, B. N., and others, 1936, Mineral resources of the region around Boulder Dam: U. S. Geol. Survey Bull. 871. Heyl, G. R., 1948a, Ore deposits of Copperopolis,, Calaveras County, California, in Copper in Cali­ fornia: California Div. Mines Bull. 144, pt. 1. , 1948b, The zinc-copper mines of the Quail Hill area, Calaveras County, California, in Copper in California; California Div. Mines 144, pt. 1. Heyl, G. R., Cox, M. W., and Eric, J. H., 1948, Penn zinc-copper mine, Calaveras County, California in Copper in California: California Div. Mines Bull. 144, pt. 1. Heyl, G. R., and Eric, J. H., 1948, Newton copper mine, Amador County, California, in Copper in California: California Div. Mines Bull. 144, pt. 1. Hill, J. M., 1915, Some mining districts in north­ eastern California and northwestern Nevada: U. S. Geol. Survey Bull. 594. , 1916, Notes on some mining districts in eastern Nevada: U. S. Geol. Survey Bull. 648. Hogue, W. G., and Wilson, E. ID., 1950, Bisbee or Warren district, in Arizona zinc and lead de­ posits: Arizona Bur. Mines Bull. 156, Geol. Ser. 18, pt. 1, chap. 2. Hosterman, J. W., 1956, Geology of the Murray area, Shoshone County, Idaho: U. S. Geol. Survey Bull. 1027-P. Howard, L. 0., 1925, The Chewelah and Colville districts of northeastern Washington: Mining and Metallurgy, v. 6, no. 222. Hulin, C. ID., 1925, Geology and ore deposits of the Randsburg quadrangle, California: California State Mining Bur., Bull. 95. Humphrey, F. L., 1945, Geology of the Groom dis­ trict, Lincoln County, Nevada: Nevada Univ. Bull., v. 39, no. 5. Hunt, R. N., and Peacock, H. G., 1948, Lead and lead-zinc of the Bingham district, Utah, in Dunham, K. C., ed., Symposium on the geology, paragenesis, and reserves of the ores of lead and zinc: Internat. Geol. Cong., 18th, London, Huttl, J. B., 1958, How scientific exploration found Pima mine: Eng. Mining Jour., v. 159, no. 3. Irving, J. D., and Bancroft, Howland, 1911, Geology and ore deposits near Lake City, Colo.: U. S. Geol. Survey Bull. 478. Jackson, C. F., Knaebel, J. B., and Wright, C. A., 1935, Lead and zinc mining and milling in the United States; Current practices and costs: U. S. Bur. Mines Bull. 381.

References Cited (cont'd.) Jenkins, 0. P., 1924, Lead deposits of Pend Oreille and Stevens Counties, Washington: Washington Geol. Survey Bull. 31. Jicha, H. L., Jr., 1954, Geology and mineral de­ posits of Lake Valley quadrangle, Grant, Luna, and Sierra Counties, New Mexico: New Mexico Bur. Mines and Mineral Resources, Bull. 37. Johnston, W. D., Jr., 1940, The gold quartz veins of Grass Valley, Calif.: U. S. Geol. Survey Prof. Paper 194. Julihn, C. E., and Horton, F. W., 1938, Mines of the southern Mother Lode region, part 1, Cala­ varas County [California]: U. S. Bur. Mines Bull. 413. , 1940, Mines of the southern Mother Lode region, part 2, Tuolumne and Mariposa Counties [California]: U. S. Bur. Mines Bull. 424. Karlstrom, T. N. V., 1948, Geology and ore deposits of the Hecla mining district, Beaverhead County, Montana: Montana Bur. Mines and Geology Mem. Kelley, V. C., 1946, Geology, ore deposits, and mines of the Mineral Point, Poughkeepsie, and upper Uncompahgre districts, Ouray, San Juan, Hinsdale Counties, Colorado: Colorado Sci. Soc. Proc., v. 14, no. 7. Kerr, P. F., 1936, The tungsten mineralization at Silver Dyke, Nevada: Nevada Univ. Bull., v. 30, no. 5. Kiersch, G. A., 1951, Seventy-nine mine area, in Arizona zinc and lead deposits: Arizona Bur. Mines Bull. 158, Geol. Ser. 19, pt. 2, chap. 8. Kiilsgaard, T. H., 1949, The geology and ore de­ posits of the Boulder Creek mining district, Custer County, Idaho: Idaho Bur. Mines and Geology Pamph. 88. , 1950, The geology and ore deposits of the Triumph-Parker mine mineral belt, in And­ derson, A. L., Kiilsgaard, T. H., and Fryklund, V. C., Jr., Detailed geology of certain areas in the Mineral Hill and Warm Springs mining districts, Blaine County, Idaho: Idaho Bur. Mines and Geology Pamph. 90. King, P. B., and Flawn, P. T., 1953, Geology and mineral deposits of the Pre-Cambrian rocks of the Van Horn area, Texas: Texas Univ. Pub. Kinkel, A. R., Jr., Hall, W. E., and Albers, J. P., 1956, Geology and base-metal deposits of West Shasta copper-zinc district, Shasta County, Cali­ fornia: U. S. Geol. Survey Prof. Paper 285. Kirkham, V. R. D., and Ellis, E. W., 1926, Geology and ore deposits of Boundary County, Idaho: Idaho Bur. Mines and Geology Bull. 10. Klepper, M. R., Weeks, R. A., and Ruppel, E. T., 1957, Geology of the southern Elkhorn Mountains, Jefferson and Broadwater Counties, Montana: U. S. Geol. Survey Prof. -Paper 292. Knopf, Adolph, 1913, Ore deposits of the Helena mining region, Montana: U. S. Geol. Survey Bull. 527. , 1918a, A geologic reconnaissance of the Inyo Range and the eastern slope of the southern Sierra Nevada, California: U. S. Geol. Survey Prof. Paper 110. , 1918b, The antimonial silver-lead veins of the Arabia district, Nevada: U. S. Geol. Survey Bull. 660-H. , 1921a, Ore deposits of Cedar Mountain, Mineral County, Nevada: U. S. Geol. Survey Bull. 725-H. , 1921b, The Divide silver district, Nev.: U. S. Geol. Survey Bull. 715. , 1922, The Candelaria silver district, Nevada: U. S. Geol. Survey Bull. 735-A. , 1926, Recent developments in the Aspen district, Colorado: U. S. Geol. Survey Bull. 785-A. , 1929, The Mother Lode system of California: U. S. Geol. Survey Prof. Paper 157. , 1935, The Plumas County Copper Belt, Calif., in Copper resources of the world: In­ ternat. Geol. Cong., 16th, Washington 1933. Koch, G. S., Jr., 1959, Lode mines of the central part of the Granite mining district, Grant County, Oregon: Oregon Dept. Geology and Mineral In­ dustries Bull. 49. Koschmann, A. H., and Wells, F. G., 1946, Pre­ liminary report on the Kokomo mining district, Colorado: Colorado Sci. Soc. Proc., v. 15, no. 2. Kral, V. E., 1951, Mineral Resources of Nye County, Nevada: Nevada Univ. Bull., v. 45, no. 3. Krieger, Philip, 1932, Geology of the zinc-lead deposit at Pecos, New Mexico: Econ. Geology, v. 27, no. 4. Kuhn, T. H., 1951, Bunker Hill district, in Arizona zinc and lead deposits: Arizona Bur. Mines Bull. 158, Geol. Ser. 19, pt. 2, chap. 7. Laney, F. B., 1917, The geology and ore deposits of the Virgilina district of Virginia and North Carolina: Virginia Geol. Survey, Bull. 14. Larsen, E. S., 1929, Recent mining developments in the Creede district, Colorado: U. S. Geol. Survey Bull. 811-E. Lasky, S. G., 1936, Geology and ore deposits of the Bayard area, Central mining district, N. Mex.: U. S. Geol. Survey Bull. 870. , 1938, Geology and ore deposits of the Lordsburg mining district, Hidalgo County, New Mexico: U. S. Geol. Survey Bull. 885. , 1947, Geology and ore deposits of the Little Hatchet Mountains, Hidalgo and Grant Counties, New Mexico: U. S. Geol. Survey Prof. Paper 208.

References Cited (cont'd.) Lincoln, F. C., 1923, Mining districts and mineral resources of Nevada: Reno, Nevada Newsletter Pub. Co. Lindgren, Waldemar, 1896, The gold-quartz veins of Nevada City and Grass Valley districts, California: U. S. Geol. Survey 17th Ann. Rept., pt. 2-A. , 1901, The gold belt of the Blue Mountains of Oregon: U. S. Geol. Survey 22nd Ann. Rept., pt. 2, Ore deposits, p. 551-776. , 1905, The copper deposits of the Clifton-Morenci district, Arizona: U. S. Geol. Survey Prof. Paper 44. , 1911, The Tertiary gravels of the Sierra Nevada of California: U. S. Geol. Survey Prof. Paper 73. , 1926, Ore deposits of the Jerome and Bradshaw Mountains quadrangles, Arizona: U. S. Geol. Survey Bull. 782. Lindgren, Waldemar, Graton, L. C., and Gordon, C. H., 1910, The ore deposits of New Mexico: U. S. Geol. Survey Prof. Paper 68. Lindgren, Waldemar, and Loughlin, G. F., 1919, Geology and ore deposits of the Tintic mining district, Utah: U. S. Geol. Survey Prof. Paper Lines, H. L., 1940, Mining and milling methods and costs at the Ash Peak mine of the Veta Mines, Inc., Duncan, Arizona: U. S. Bur. Mines Inf. Circ. 7119. Logan, C. A., 1922, Auburn field division, Alpine County [California]: California Mining Bur., 18th Rept. State Mineralogist, v. 18, no. 8. Lovering, T. S., 1934,Geology and ore deposits of the Breckenridge mining district, Colorado: U. S. Geol. Survey Prof. Paper 176. , 1935, Geology and ore deposits of the Montezuma quadrangle, Colorado: U. S. Geol. Survey Prof. Paper 178. Lovering, T. S., and Goddard, E. N., 1950, Geology and ore deposits of the Front Range, Colorado: U. S. Geol. Survey Prof. Paper 223. Lovitt, E. H., and Skerl, A. C., 1958, Geology of the Levitt gold mine, Wenatchee, Washington: Mining Eng., v. 10, no. 9. MacBoyle, Errol, 1919, Mines and mineral resources of Nevada County [California]: California Mining Bur., 16th Rept. State Mineralogist for 1917-1918. Matson, E. J., 1946, Exploration of the Mount Hope mine, Eureka County, Nevada: U. S. Bur. Mines Rept. Inv. 3928. , 1947, Rio Grande copper deposit, Elko County, Nev.: U. S. Bur. Mines Rept. Inv. 4120. McCulloch, R. B., and Huleatt, W. P., 1946, Explo­ ration of the Big Four zinc -silver mine, Summit County, Colorado: U. S. Bur. Mines Rept. Inv. McKinstry, H. E., and Mikkola, A. K., 1954, The Elizabeth copper mine, Vermont: Econ. Geology, v. 49, no. 1. Merrill, C. W., 1930, Economic relations of silver to other metals in argentiferous ores: U. S. Bur. Mines Econ. Paper 10. Merrill, F. J. H., 1919, Mines and mineral resources of Orange County, [California]: California Mining Bur., 15th Rept. State Mineralogist for 1915-1916, pt. 4, chap. 2. , 1930a, Sacramento field division, Butte County [California]: California State Mineralogist, Div. Mines, v. 26, no. 3. Logan, C. A., 1930b, Sacramento field division, Yuba County [California]: California State Mineralogist, Div. Mines, v. 26, no. 3. , 1936, Gold mines of Placer County [California]: California Jour. Mines and Geology, v. 32, no. 1. , 1941, Mineral resources of Nevada County [California]: California Jour. Mines and Geology, v. 37, no. 3. Long, A., Silverman, A. J., and Kulp, J. L., 1960, Isotopic composition of lead and Precambrian mineralization of the Coeur d'Alene district, Idaho: Econ. Geology, v. 55, no. 4. Loughlin, G. F., and Koschmann, A. H., 1935, Geology and ore deposits of the Cripple Creek district, Colo.: Colorado Sci. Soc. Proc., v. 13, no. 6. , 1942, Geology and ore deposits of the Magdalena mining district, New Mexico: U. S. Geol. Survey Prof. Paper 200. Lovering, T. S., 1930, The New World or Cooke City mining district, Park County, Montana: U. S. Geol. Survey Bull. 811-A. Mertie, J. B., 1940, Placer Gold in Alaska: Wash. Acad. Sci. Journ., v. 30, no. 3. Mertie, J. B., Jr., Fischer, R. P., and Hobbs, S. W., 1951, Geology of the Canyon Ferry quadrangle, Montana: U. S. Geol. Survey Bull. 972. Murphy, F. M., 1930, Geology of the Panamint silver district, California: Econ. Geology, v. 25, no. '4. Nolan, T. B., 1935a, The Gold Hill mining district, Utah: U. S. Geol. Survey Prof. Paper 177. , 1935b, The underground geology of the Tonopah mining district, Nevada: Nevada Univ. Bull., v. 29, no. 7. , 1936, The Tuscarora mining district, Elko County, Nevada: Nevada Univ. Bull., v. 30, no. 1. Norman, L. A., Jr., and Stewart, R. M., 1951, Mines and mineral resources of Inyo County [Cali­ fornia]: California Jour. Mines and Geology, v. 47, no. 1. Oesterling, W. A., 1952, Geologic and economic significance of the Hutson zinc mine, Salem, Kentucky--its relation to the Illinois-Kentucky fluorspar district: Econ. Geology, v. 47, no. 3.

References Cited (cont'd.) Overton, T. D., 1947, Mineral resources of Douglas, Ormsby, and Washoe Counties [Nevada]: Nevada Univ. Bull., v. 46, no. 9. Page, B. M., 1959, Geology of the Candelaria mining district, Mineral County, Nevada: Nevada Bur. Mines Bull. 56. Paige, Sidney, 1911, The ore deposits near Pinos Altos, New Mexico: U. S. Geol. Survey Bull. 470-B. , 1916, Description of Silver City quadrangle [New Mexico]: U. S. Geol. Survey Geol. Atlas, Folio 199. , 1924, Geology of the region around Lead, South Dakota, and its bearing on the Homestake ore body: U. S. Geol. Survey Bull. Pardee, J. T., 1917, The Dunkleberg mining dis­ trict, Granite County, Montana: U. S. Geol. Survey Bull. 660-G. , 1918, Ore deposits of the northwestern part of the Garnet Range, Mont.: U. S. Geol. Survey Bull. 660-F. Pardee, J. T., and Hewett, D. F., 1914, Geology and mineral resources of the Sumpter quadrangle [Oregon]: Oregon Bur. Mines and Geology, Mineral Resources, v. 1, no. 6, geologic map included, scale 1:125,000. Pardee, J. T., and Park, C. F., Jr., 1948, Gold deposits of the southern Piedmont: U. S. Geol. Survey Prof. Paper 213. Pardee, J. T., and Schrader, F. C., 1933, Metalli­ ferous deposits of the Greater Helena mining region, Montana: U. S. Geol. Survey Bull. 842. Park, C. F., Jr., and Cannon, R. S., Jr., 1943, Geology and ore deposits of the Metaline quad­ rangle, Washington: U. S. Geol. Survey Prof. Paper 202. Parks, H. M., and Swartley, A. M., 1916, Handbook of the mining industry of Oregon: Oregon Bur. Mines and Gology, Mineral Resources, v. 2, no. 4. Patton, H. B., 1917, Geology and ore deposits of the Platoro-Summitville mining district, Colo.: Colo­ rado Geol. Survey Bull. 13. Patty, E. N., 1921, The metal mines of Washington: Washington Geol. Survey Bull. 23. Perry, E. S., 1932, The Butte mining district, Mont­ ana: Internat. Geol. Cong., 16th, Washington 1933, Guidebook 23. Peterson, N. P., 1950, Lead and zinc deposits in the Globe-Miami districts, Arizona, in Arizona zinc and lead deposits: Arizona Bur. Mines Bull. 156, Geol. Ser. 18, pt. 1, chap. 2. Peterson, N. P., Gilbert, C. M., and Quick, G. L., 1951, Geology and ore deposits of the Castle Dome area, Gila County, Arizona: U. S. Geol. Survey Bull. 971. Peterson, V. E., 1942, A study of the geology and ore deposits of the Ashbrook silver mining district, Utah: Econ. Geology, v. 37, no. 6. Pettee, W. H., 1880, Report of an examination of portions of the gravel mining region of Cali­ fornia; in Placer, Nevada, Yuba, Sierra, Plumas, and Butte Counties: Harvard Coll., Mus. Comp. Zoology Mem., v. 6, no. 1, app. 4. Piper, A. M., and Laney, F. B.,'1926, Geology and metalliferous resources of the region around Silver City, Idaho: Idaho Bur. Mines and Geology, Bull. 11. Popoff, C. C., 1953, Lead-zinc deposits of the Dunkle­ berg district, Granite County, Montana: U. S. Bur. Mines Rept. Inv. 5014. Proctor, P. D., 1953, Geology of the Silver Reef (Harrisburg) mining district, Washington County, Utah: Utah Geol. and Mineralog. Survey Bull. 44. Prout, J. W., Jr., 1940, Geology of the Big Blue group of mines, Kernville, California: California Jour. Mines and Geology, v. 36, no. 4. Ransome, A. L., 1940, General geology and ores of the Blind Spring Hill mining district, Mono County, California: California Jour. Mines and Geology, v. 36, no. 2. Ransome, F. L., 1901a, A report on the economic geology, of the Silverton quadrangle, Colorado: U. S. Geol. Survey Bull. 182. , 1901b, The ore deposits of the Rico Mountains, Colorado: U. S. Geol. Survey 22nd Ann. Rept., pt. 2, Ore deposits, p. 229-397. , 1903, Geology of the Globe copper district, Arizona: U. S. Geol. Survey Prof. Paper 12. , 1909a, The geology and ore deposits of Goldfield, Nev.: U. S. Geol. Survey Prof. Paper 66. , 1909b, The Hornsilver district, Nev.: U. S. Geol. Survey Bull. 380-A. , 1919, The copper deposits of Ray and Miami, Arizona: U. S. Geol. Survey Prof. Paper Ransome, F. L., and Calkins, F. C., 1908, The geology and ore deposits of the Coeur d'Alene region, Idaho: U. S. Geol. Survey Prof. Paper 62. Reed, G. C., 1950, Mines and mineral deposits (except fuels), Park County, Mont.: U. S. Bur. Mines Inf. Circ. 7546. , 1951, Mines and mineral deposits (except fuels), Broadwater County, Mont.: U. S. Bur. Mines Inf. Circ. 7592. Reed, J. C., 1937, Geology and ore deposits of the Warren district, Idaho County, Idaho: Idaho Bur. Mines and Geology Pamph. 45. , 1939, Geology and ore deposits of the Florence mining district, Idaho County, Idaho: Idaho Bur. Mines and Geology Pamph. 46.

References Cited (cont'd.) Richard, K. E., and Courtright, J. H., 1954, Structure and mineralization at Silver Bell, Arizona: Mining Eng., v. 6, no. 11. Roberts, R. J., 1951, Geology of the Antler Peak quadrangle, Nevada: U. S. Geol. Survey Geol. Quad. Map GQ-10, scale, 1:62,500. Robertson, A. F., 1950, Mines and mineral de­ posits (except fuels), Fergus County, Mont.: U. S. Bur. Mines Inf, Circ. 7544. , 1951, Mines and mineral deposits (except fuels), Cascade County, Mont.: U. S. Bur. Mines Inf. Circ. 7589. Robertson, F. S., 1953, Geology and mineral de­ posits of the Zosell (Emery) mining district, Powell County, Montana: Montana Bur. Mines and Geology Mem. 34. Roby, R. N., 1950, Mines and mineral deposits (except fuels), Meagher County, Montana: U. S. Bur. Mines Inf. Circ. 7540. Ross, C. P., 1925a, Ore deposits of the Saddle Mountain and Banner mining districts, Ariz.: U. S. Geol. Survey Bull. 771. , 1925b, Geology and ore deposits of the Aravaipa and Stanley mining districts, Graham County, Arizona: U. S. Geol. Survey Bull. 763. , 1927, The Vienna district, Blaine County, Idaho: Idaho Bur. Mines and Geology Pamph. 21. , 1930, Geology and ore deposits of the Seafoam, Alder Creek, Little Smoky and Willow Creek mining districts, Custer and Camas Counties, Idaho: Idaho Bur. Mines and Geology Pamph. 33, , 1933, The Dome mining district, Butte County, Idaho: Idaho Bur. Mines and Geology Pamph. 39. , 1937, Geology and ore deposits of the Bayhorse region, Custer County, Idaho: U. S. Geol. Survey Bull. 877. , 1941, The metal and coal mining districts of Idaho, with notes on the nonmetallic mineral resources of the State: Idaho Bur. Mines and Geology Pamph. 57. , 1943, Geology and ore deposits of the Shafter mining district, Presidio County, Texas: U. S. Geol. Survey Bull. 928-B. Ross, C. S., 1935, Origin of the copper deposits of the Ducktown type in the southern Appalachian region: U. S. Geol. Survey Prof. Paper 179. Sahinen, U. M., 1939, Geology and ore deposits of the Rochester and adjacent mining districts, Madison County, Montana: Montana Bur. Mines and Geology Mem. 19. , 1950, Geology and ore deposits of the Highland Mountains, southwestern Montana: Mont­ ana Bur. Mines and Geology Mem. 32. Sahinen, U. M., 1957, Mines and mineral deposits of Missoula and Ravalli Counties, Montana: Montana Bur. Mines and Geology Bull. 8. Sales, R. H., 1914, Ore deposits at Butte, Montana: Am. Inst. Mining Engineers Trans, v. 46. Sampson, Edward, 1928, Geology and silver ore de­ posits of the Pend Oreille district, Idaho: Idaho Bur. Mines and Geology Pamph. 31. Sampson, R. J., 1937, Mineral resources of the Resting Springs region, Inyo County [California]: Cali­ fornia Jour. Mines and Geology, v. 33, no. 4. 1940, Mineral resources of Mono County [California]: California Jour. Mines and Geology, v. 36, no. 2. Sampson, R. J., and Tucker, W. B., 1942, Mineral resources of Imperial County [California]: California Jour. Mines and Geology, v. 38, no. 2. Schafer, P. A., 1935, Geology and ore deposits of the Nihart mining district, Cascade County, Montana: Montana Bur. Mines and Geology Mem. 13. Schmitt, H. A., 1935, The central mining district, N. Mex., Am. Inst. Mining Metall. Engineers Trans., v. 115. Schmitt, H. A., Clippinger, D. M., Roper, W. J., and Toombs, Harvey, 1959, Disseminated deposits at the Esperanza copper mine [Arizona]: Arizona Geol. Soc., Southern Arizona Guidebook II. Schrader, F. C., 1912, A reconnaissance of the Jar­ bidge, Contact, and Elk Mountain mining districts, Elko County, Nev.: U. S. Geol. Survey Bull. 497. , 1915, Mineral deposits of the Santa Rita and Patagonia Mountains, Arizona: U. S. Geol. Survey Bull. 582. , 1923, The Jarbidge mining district, Nev., with a note on the Charleston district: U. S. Geol. Survey Bull. 741. , 1931, Spruce Mountain district, Elko County and Cherry Creek (Egan Canyon) district, White Pine County [Nevada]: Nevada Univ. Bull., v. 25, no. 7. , 1935, The Contact mining district,Nev.: U. S. Geol. Survey Bull. 847-A. Schwartz, G. M., 1937, Paragenesis of iron sulfides in a Black Hills deposit: Econ. Geology, v. 32, no. 6. , 1953, Geology of the San Manuel copper deposit, Arizona: U. S. Geol. Survey Bull. 256. Searles, Fred, Jr., 1948, A contribution to the pub­ lished information on the geology and ore deposits of Goldfield, Nevada: Nevada Univ. Bull., v. 42, no. 5. Sellards, E. H., and Baker, C. L., 1934, The geology of Texas; structural and economic geology: Texas Univ. Bull. 3401, v. 2. Sharp, William, 1948, The story of Eureka: Am. Inst. Mining, Metall. Engineers Trans., v. 178.

References Cited (cont'd.) Shenon, P. J., 1931, Geology and ore deposits of Bannack and Argenta, Montana: Montana Bur. Mines and Geology Bull. 6. , 1933, Copper deposits in the Squaw Creek and Silver Peak districts and at the Almeda mine, southwestern Oregon, with notes on the Pennell and Farmer and Banfield prospects: U. S. Geol. Survey Circ. 2. Shenon, P. J., and McConnel, R. H., 1939, The silver belt of the Coeur d'Alene district, Idaho: Idaho Bur. Mines and Geology Pamph. 50. Shenon, P. J., and Reed, J. C., 1934, Geology and ore deposits of the Elk City, Orogrande, Buffalo Hump and Tenmile districts, Idaho County, Idaho: U. S. Geol. Survey Circ. 9. Shenon, P. J., and Taylor, A. V., 1936, Geology and ore occurrence of the Hog Heaven mining district, Flathead County, Montana: Montana Bur. Mines and Geology Mem. 17. Short, M. N., Galbraith, F. W., Harshman, E. N., and others, 1943, Geology and ore deposits of the Superior mining area, Arizona: Arizona Bur. Mines Bull. 151, Geol. Ser. 16. Singewald, Q. D., 1951, Geology and ore deposits of the upper Blue River area, Summit County, Colorado: U. S. Geol. Survey Bull. 970. , 1955, Sugar Loaf and St. Kevin mining districts, Lake County, Colorado: U. S. Geol. Survey Bull. 1027-E. Singewald, Q. D., and Butler, B. S., 1933, Suggestions for prospecting in the Alma district, Colorado: Colorado Sci. Soc. Proc., v. 13, no. 4. , 1941, Ore deposits in the vicinity of the London fault, Colorado: U. S. Geol. Survey Bull. 911. Sorenson, R. E., 1927, The geology and ore deposits of the South Mountain mining district, Owyhee County, Idaho: Idaho Bur. Mines and Geology Pamph. 22. Spencer, A. C., 1908, Magnetite deposits of the Cornwall type in Pennsylvania: U. S. Geol. Survey Bull. 359. , 1917, The geology and ore deposits of Ely, Nevada: U. S. Geol. Survey Prof. Paper 96. Spiroff, Kiril, 1938, Geological observations of the Block P mine, Hughesville, Mont.: Econ. Geology, v. 33, no. 5. Spurr, J. E., 1898, Geology of the Aspen mining district, Colorado, with atlas: U. S. Geol. Survey Mon. 31. , 1906, The southern Klondyke district, Esmeralda County, Nevada--a study in metalli­ ferous quartz veins of magmatic origin: Econ. Geology, v. 1, no. 4. Stewart, C. A., 1912, The geology and ore deposits of the Silverbell mining district, Arizona: Am... Inst. Mining Engineers Trans., v. 43. Stinson, M. C., 1957, Geology of the Island Mountain copper mine, Trinity County, California: Cali­ fornia Jour. Mines and Geology, v. 53, nos. 1-2. Stoddard, Carl, and Carpenter, J. A., 1950, Mineral resources of Storey and Lyon Counties, Nevada: Nevada Univ. Bull., v. 44, no. 1. Stone, R. W., 1911, Geologic relation of ore de­ posits in the Elkhorn Mountains, Montana: U. S. Geol. Survey Bull. 470. Stringham, B. F., 1942, Mineralization in the West 'Untie mining district, Utah: Geol. Soc. America Bull. 53, no. 2. Swartley, A. M., 1914, Ore deposits of northeastern Oregon: Oregon Bur. Mines and Geology, Mineral Resources, v. 1, no. 8. Tansley, Wilfred, Schafter, P. A., and Hart, L. H., 1933, A geological reconnaissance of the Tobacco Root Mountains, Madison County, Montana: Mont­ ana Bur. Mines and Geology Mem. 9. Tarr, W. A., 1936, Origin of the southeastern Miss­ ouri lead deposits: Econ. Geology, v. 31, nos. 7-8. Taylor, A. V., Jr., 1942, Quartz Hill district, near Divide, Montana, in Newhouse, W. H., ed., Ore deposits as related to structural features: Prince­ ton, New Jersey, Princeton Univ. Press. Tenney, J. B., 1928, The mineral industries of Arizona: Arizona Bur. Mines Bull. 125, no. 1. , 1935, The copper districts of Arizona, in Copper resources of the World: Internat. Geol. Cong., 16th, Washington 1933, p. 189-201. Thomas, B. E., 1949, Ore deposits of the Wallapai district, Arizona: Econ. Geology, v. 44, no. 8. Treves, S. B., and Melear, J. D., 1953, The geology and ore deposits of the Seafoam mining district, Custer County, Idaho: Idaho Bur. Mines and Geology Pamph. 96. Tucker, W. B., 1922, Silver lodes of the South Fork mining district, Shasta County [California]: Cali­ fornia Mining Bur., 18th Rept. State Mineralogist, v. 18, no. 7. , 1927, Los Angeles field division, Mineral resources of Santa Catalina Island [California]: California Mining Bur., 23rd Rept. State Mineralogist, v. 23, no. 1. , 1935, Mining activity at Soledad Mountain and Middle Buttes, Mojave mining district, Kern County [California]: California Jour. Mines and Geology, v. 31, no. 4. Tucker, W. B., and Sampson, R. J., 1940, Economic mineral deposits of the Newberry and Ord Moun­ tains, San Bernardino County, California: Cali­ fornia Jour. Mines and Geology, v. 36, no. 2. , 1945, Mineral resources of Riverside County [California]: California Jour. Mines and Geology, v. 41, no. 3. Tucker, W. B., Sampson, R. J., and Oakeshott, G. B., 1949, Mineral resources of Kern County [Cali­ fornia]: California Jour. Mines and Geology, v. 45, no. 2.

References Cited (cont'd.) Tweto, Ogden, and Lovering, T. S., 1947, The Gilman district, Eagle County [Colorado], in Mineral resources of Colorado: Colorado Mineral Re­ sources Board [Pub.], pt. 2. Umpleby, J. B., 1910, Geology and ore deposits of Republic mining district [Washington]: Washington Geol. Survey Bull. 1. , 1913, Geology and ore deposits of Lemhi County, Idaho: U. S. Geol. Survey Bull. , 1914, Ore deposits in the Sawtooth quadrangle, Blaine and Custer Counties, Idaho: U. S. Geol. Survey Bull. 580. Umpleby, J. B., and Jones, E. L., Jr., 1923, Geology and ore deposits of Shoshone County, Idaho: U. S. Geol. Survey Bull. 732. Umpleby, J. B., Westgate, L. G., and Ross, C. P., 1930, Geology and ore deposits of the Wood River region, Idaho: U. S. Geol. Survey Bull. 814. United States Bureau of Mines, 1953-1957: Minerals Yearbook. Vanderburg, W. 0., 1936, Reconnaissance of mining districts in Pershing County, Nev.: U. S. Bur. Mines Inf. Circ 6902. , 1937, Reconnaissance of mining districts in Mineral County, Nevada: U. S. Bur. Mines Inf. Circ. 6941. , 1938a, Reconnaissance of mining districts in Humboldt County, Nevada: U. S. Bur. Mines Inf. Circ. 6995. , 1938b, Reconnaissance of some mining districts in Eureka County, Nevada: U. S. Bur. Mines Inf. Circ. 7022. 1939, Reconnaissance of mining districts in Lander County, Nevada: U. S. Bur. Mines Inf. Circ. 7043. , 1940, Reconnaissance of mining districts in Churchill County, Nev.: U. S. Bur. Mines Inf. Circ. 7093. Vanderwilt, J. W., 1935, Revision of structure and stratigraphy of the Aspen district, Colorado, and its bearing on the ore deposits: Econ. Geology, v. 30, no. 3. , 1937, Geology and mineral deposits of the Snowmass Mountain area, Gunnison County, Colorado: U. S. Geol. Survey Bull. 884. , 1947, Gunnison County [Colorado], in Mineral resources of Colorado: Colorado Min­ eral Resources Board [Pub.], pt. 1. Wallace, R. E., and Hosterman, J. W., 1956, Re­ connaissance geology of western Mineral County, Montana: U. S. Geol. Survey Bull. 1027-M. Watson, T. L., 1905, Lead and zinc deposits of Virginia: Virginia Geol. Survey Bull. 1. Weaver, C. E., 1920, The mineral resources of Stevens County [Washington]: Washington Geol. Survey Bull. 20. Webster, Russell, 1958, Exploration extends Magma's future: Mining Eng., v. 10, no. 10. Weed, W. H., 1900, Geology of the Little Belt Moun­ tains, Montana, with notes on the mineral de­ posits of the Neihart, Barker, Yogo, and other districts: U. S. Geol. Survey 20th Ann. Rept. pt. 3-C. Westgate, L. G., and Knopf, Adolph, 1932, Geology and ore deposits of the Pioche district, Nevada: U. S. Geol. Survey Prof. Paper 171. White, W. S., and Wright, J. C., 1954, The White Pine copper deposit, Ontonagon County, Michigan: Econ. Geology, v. 49, no. 7. Wilson, E. D., 1927, Geology and ore deposits of the Courtland-Gleeson region, Arizona: Arizona Bur. Mines Bull. 123, Geol. Ser. 5. , 1950a, Aravaipa district, in Arizona zinc and lead deposits: Arizona Bur. Mines Bull. 156, Geol. Ser. 18, pt. 1, chap. 5. , 1950b, Pima district, in Arizona zinc and lead deposits: Arizona Bur. Mines Bull. 156, Geol. Ser. 18, pt. 1, chap. 4. , 1951a, Silver A Eureka districts, in Arizona zinc and lead deposits: Arizona Bur. Mines Bull. 158, Geol. Ser. 19, pt. 2, chap. 9. , 1951b, Castle Dome district, in Arizona zinc and lead deposits: Arizona Bur. Mines Bull. 158, Geol. Ser. 19, pt. 2, chap. 10. , 1951c, Empire district, in Arizona zinc and lead deposits: Arizona Bur. Mines Bull. 158, Geol. Ser. 19, pt. 2, chap. 6. , 1951d, Dragoon Mountains, in Arizona zinc and lead deposits: Arizona Bur. Mines Bull. 158, Geol. Ser. 19, pt. 2, chap. 2. Wilson, E. D., Cunningham, J. B., and Butler, G. M., 1934, Arizona lode gold mines and gold mining: Arizona Bur. Mines Bull. 137, Mineral Tech. Ser. 37. Winchell, A. N., 1914, The mining districts of the Dillon quadrangle, Montana, and adjacent areas: U. S. Geol. Survey Bull. 574. Winslow, Arthur, 1894, Lead and zinc deposits [Miss­ ouri]: Missouri Geol. Survey, v. 7. Wright, L. A., Stewart, R. M., Gay, T. E. Jr., and Hazenbush, G. C., 1953, Mines and mineral deposits of San Bernardino County, California: California Jour. Mines and Geology, v. 49, nos 1-2, Wright, L. B., 1947, Geologic relations and new ore bodies of the Republic mining district, Washington: Am. Inst. Mining Metall. Engineers, v. 11, no. 4, Mining Tech. Pub. 2197. Youngberg, E. A., and Wilson, T. L., 1952, The geology of the Holden mine [Washington]: Econ. Geology, v. 47, no. 1. USGS LIBRARY - RESTON 111101111111111111 3 1818 00119586 4 INT,DUP. ,D. C .62- 11467