None
Serpentine asbestos is formed by the alteration of peridotite or certain other rocks. The highest-grade asbestos deposits are veinlets in serpentine. It is believed that they have been formed through the agency of waters that coursed through cracks and fissures, either hot waters soon after the rocks had formed or surface waters later, when the rocks were eroded. The most productive deposits of asbestos in North America are at Thetford, Quebec,' in a belt of igneous rocks that extends southwestward into northern Vermont' (see Fig. 208). The asbestos occurs as cross-fiber veins, closely spaced in a serpentine that has probably been formed by alteration from peridotite. The veinlets, which are from a fraction of an inch to several inches thick, are believed to be alteration products of the igneous rocks in which they are found. Veins of chrysotile asbestos in serpen- tine are worked in Orleans and Lamoille counties, Vermont. Near Casper, Wyo.,* veins of cross-fiber asbestos occur in serpen- tine, which also is probably an alteration product of peridotite. ' CiRKEL, Fritz; Chrysotile Asbestos, Its Occurrence, Exploitation, MillinK, and Uses, 2d ed. Canada Dept. Mines, Mines Branch, 1910. Dresser, J. A,; On the Asbestos Deposits of the Eastern Townships of Quebec. Econ. Geol., vol. 4, p. 130, 1909. Ells, R. W.: Btdktin on Asbestos, Canada Geol. Survey, 1903. •DiLLEB, J. S.: The Types and Modes ot Occurrence of Asbestos in the United States. Canadian Min. Inst. Quart. Bull. No. 13, pp. 45-58, Februiirj-, 1911. Marmters, V. F.: Pctrogmphy of the AmphilraUte, Serpentine, and Asso- eiated Asbestos Deposits of Belvedere Mountain, Vermont. Geol. Soc. Aiiierii-a Bull., vol. 10, pp. 419-446, 1905. RtoiiARDSON, C. H.I .Asbestos in Vermont, Vermont State Geologist .SVtF<7,//, R,pt., pp. ai5-330, 1910. 'Lakks, AiiTdVH: The Wyoming Asbestos Deposits and Mills. -Uin. ,SV)„ <)<'1ob.T2S, 1909. Dii.r.KFi, J. S, : 'Hio 'IVpes, Modes of Occurrenec, and Important Deposits of Asl.c>:'1c,M in till- I'niteil Htntes. U. S. Geol. Sur\-ey Butt. 470, pp. 512- oyGoo»^Ic DEPOSITS OF THE NONMETALS 583 In the Grand Canyon of Arizona asbestos occurs with serpentine in limestone. Diller considers it to be derived from material of sedimentary origin. The asbestos rocks are near an intruding diabase sill, and the parent olivine minerals may have been formed by contact-raetaraorphic processes. In Idaho, about H miles southeast of Kamiah, ledges of antho- Fio. 208. — Map showing |locatioa of asbestos deposits in t and adjoining portion of Canada. (After Diuer, U. S. phyllite rock are found intruded in mica schist. This rock is quarried and shipped to Spokane, Wash. Most of the asbestos produced in the United States is mined in Georgia. At Sail Mountain, Ga., according to Diller, autho- phyllite asbestos occurs in lenticular masses in gneiss, which is believed to be an altered igneous rock. Near Bedford, Va., there are deposits of mass-fiber presumably derived from basic rocks. The production of asbestos in the United States is small. In 1915 it amounted to 1,731 short tons, valued at J76,952. The value of the annual Canadian output is about $3,000,000. As- oyGoo»^Ic 584 THE PRINCIPLES OF ECONOMIC GEOLOGY bestOB is used tat mokiiig firepnxif theater curtains, ropii, clotbiitg, etc. When felted it is a good noaoonduotor of heat and electricity and finds many usee as an insulator. The lower 'grades are mixed with cement and manufactured into fireproof shingles. These are cheap and for some purposes are supcfior to tile and slate. Asbestos plaster is used in theaters to deaden noise. Boards are made of asbestos and cement. The danaod is increasing, especially for the low-i>riced materials.' HOITAZITB AlfD XBROTIME Monazite is normally cerium phosphate (CePO*), but rare- earth metala — thorium, praseodymium, lanthanum, neodymium — are generally present in it. Xenotime (YtP04] is a phoaphste of yttria, with rare earths of the cerium group. These minerali are exploited for the rare earths they contain, especially for thorium, which is used for making glowers and mantles for lights. The principal production* is derived from the Carolinas, east of the Blue Ridge. The country is an area of gneisB, schist, and granite, cut by various intrusive rocks, includii^ extensive dikes of pegmatite. The monazite is mined muoly from placers, but some is mined from pegmatized gneiss in [dace, especially where the gneiss has rotted. Small amounts of zircon (ZrOi) are present in many igneoiu rocks. Some pegmatites contain considerable amounts. Zircon resists weathering processes and is concentrated in stream graveli derived from zircon-bearing rocks. In the Carolinas zircon i» associated with monazite in gravels. Near Zirconia, Hendetson County, North Carolina, zircon is obtained by washing the de- composed croppings of a p^matite dike.* Zircon-bearing pegm^ tites occur also near Cash in the Wichita Mountains, Oklahoma.* Zircon is used for the manufacture of zirconium compounds, which are used in making glowers for the Nemst electric light. 'DiLLBR, J. S.: U. S. Geol. Survey Mineral Resourcet, 1911, part 2, p. 995, 1912. * Fratt, J. H., and Stf.krett, D. B.: Monatite and Moiuuit« Mining in the Carolinas. Am. Inat. Min. Eng. Tram., vol. 40, pp. 488-511, 1909. iSterrett, D. B.: Monaiite and Zirrun. U. 8. Gcol. Survey JUtiunil ResouTcea, 1011, part 2, pp. 1193-119G, 1912. ' Sterrbtt, D. B.: Monazite and Zirron. U. S. Geol. Survey Mintr^ Heiourcet, 1907, part 2, p. 792, 1908. oyGoo»^Ic DEPOSITS OF THE NONMETALS Occmrence. — Water (HjO) is essential for aninial and vegetable life, and it plays a part in the genesis of all minerals. A part of the rain water that falls upon the earth soaks into the ground and, where openings are available, reissues as springs. The dis- tribution and movements of ground water are mentioned under weathering and also in the discussion of the enrichment of ores. Nearly everywhere the ground contains some water, but the amount is exceedingly variable, depending on the climate, the structure of the rocks, the distribution of fissures, etc. Below the vadose zone (page 132) the rocks are generally saturated with water. At greater depths, however, the rocks because of pressure are tight, and water if present is nearly static. Estimates of the amount of water in the earth's crust/ stated in terms of the thickness of a uniform blanket of water spread over the surface, range from less than -100 feet to nearly 1,000 feet. Almost all deep mines encounter more or less water. Wells sunk for water frequently encounter a supply only a few feet below the surface. Some, however, go hundreds of feet to water, the depth depending on local conditions, On the flood plains of rivers water is generally reached near the surface. Many wells in glacial drift encounter water at shallow depths. Some deep borings are dry. Artesian Water. — Deep borings encountering abundant water supply are commonly termed artesian wells (from Artois, France, where wells of this sort have long been used). Originally, how- ever, this term was applied only to flowing wells. The condi- tions that are favorable to the development of an artesian circu- lation are (1) a porous bed of size sufficient to serve as a carrier and reservoir, (2) an impervious bed above it, (3) a collecting area higher than the point of issue. ^ Sandstones and gravels are good water carriers. The total pore space of such rocks commonly amounts to 10 per cent, or more. Because of their storage capacity thick sandstones are ' Van Hi8E, C. R.: A Treatise oq Metamorphism. U. 8. Geol, Survey Mon. 47, pp. 123-657, 1904. FuLiBR, M. L.: The -Amount ot Free Wat«r in the Earth's Cruat. U. S. Geol. Survey Waler-SupjAy Paper, 160, 1906. * Chaiiberlin, T. C: Requisite and Qualifying Conditions of Artesian Wdls. U. 8. Geol. Survey Fifth Ann, Rept., pp. 131-173, 1884. oyGoo»^Ic 586 THE PRINCIPLES OF ECONOMIC GEOLOGY better carriers than thin sandstonee. Fractured limestones or other fractured rocks may be carriers or reservoirs of water. Amygdaloidal lavas have high pore space and may carry water, but because their openings are not connected they are general]; inferior to sandstones. The shafts that penetrate many tilted vesicular flows at copper mines of Keweenaw Point, Mich., are dry in the deeper levels. For an artesian flow it is necessary that the pervious beds be capped by impervious or nearly impervious rocks (Figs. 209, 210), for otherwise the water .would escape and the water pres- sure would be lowered to a point where water would not rise in openings. In general shale forms the best cap above the per- vious beds. The character of the rocks below the water carrier is not important if such rocks do not crop out below the carrier. If the underlying rocks are impervious they will bold the water in; if they are pervious and have no outlet they will be filled with stagnant water that will prevent the downward escape of water in the carrier. The water-bearing lied should be exposed at a point above the point of issue. The water will not rise as high as the point of entry because of loss of pressure due to friction. In crystalline rocks, such as granites and schists, where joinlfi and fissures are numerous and closely spaced, these openings may serve as reservoirs of underground water. In general it is neces- sary to pump the water, and as a rule the flow is not great. In some mines in crystalline rocks, however, the flow of water is very large after numerous drifts and crosscuts have been run into the surrounding rocks. As a rule small pumps can handle the water oyGoo»^Ic DEPOSITS OF THE NONMETALS 587 encountered in sinking shafts in crystalline rocks, and unless master fissures are cut, the amount per foot of opening, of water flowing to the shaft decreases a few hundred feet below the surfaced Mineral Waters. — Natural waters are rarely pure. Even rain water carries some mineral salts, as well as carbon dioxide and a little oxygen. Many minerals are attacked by water, and as rainwater percolates through soil or rocks it gathers mineral matter, which it carries in solution. Mineral waters are grouped as table and medicinal waters. Table waters are generally not high in mineral salts; if they were their taste and physiologic effects would render them unpopular. Waters low in mineral salts and high in carbonic acid are highly prised for table use because of the palatable quality imparted by the acid. Nearly all the carbonated waters of the trade are simply pure water or water of low salinity artificially carbonated. The United States in 1915 produced 52,113,503 gallons of mineral waters valued at $5,138,794.i Medicinal waters are prized because of their therapeutic qualities. Waters carrying less than 150 parts per million of total mineral matter are classed as "low in mineral matter,"* those carrying more than 500 parts are "high," and those carrying more than 2,000 parts are "very high." As a rule waters that contain more than 1,000 parts of salts per million are not palata- ble, yet waters with 2,500 parts per million may be used for many days without discomfort, and some persons can withstand waters with more than 3,300 parts per million. Waters with as much as 5,000 parts per million are inimical to health. It has been questioned whether the mineral waters of some resorts possess the therapeutic effects that are ascribed to them. Some of these waters carry a mineral content lower than that of city supplies, Someof the "cures "reported to have been effected at these resorts are doubtless due to changes in the environment and manner of living of the patients and to copious drinking of water, which under some conditions is beneficial. Lithium salts are commonly supposed to relieve uric acid poisoning, but this ' DiscuBsiona of the water supply of the United States are given in the water-supply papers of the United States Geological Survey. * Dole, R. B. : The Concentration of Mineral Water in Relation to Thera- peutic Activity. U. S. Geol. Survey Mineral Resources, 1911, part 2, pp. 1175-1192, 1912. oyGoo»^Ic 588 THE PRINCIPLES OF ECONOMIC OEOLOGY ■ has been questioned. Sulphates in moderately lai^ doses are cathartic. Magnesium carbonate and bicarbonate are alkaline and if given in small doses will correct acidity of the stomach. Boron salts are antiseptic, and some barium salts are supposed to correct arterial troubles. Iron salts are tonic. Arsenic salts above small amounts are poison. oyGoo»^Ic INDEX Abrasives, 548 Acmit«, 13, 23, 148 Actinolite, 32, 118, 290 Additions during contact meta- morphisiD, 37 Adiroudaclc region, N. Y., 344 Adularia, 71 ^girite, 13, 148 Affinity of metals for sulphur, 157 African gold deposits, 420 Age, of certain metalliferous depoMts, 403 of deposits, of deep vein lone, S7 of dynamically metamorphosed deposits, 123 of earth, 287 of intermediate zone, 67 Agents of mineralisation, 20 Aggradational deposits, 8 Ajo, Ari»., 384 Alabandite, 508 Alaska copper deposits, 394 Albite, 13, 23, 32, 51, 148 Allanite, 13, 23, 32, 148 Alaska Gold Mines Company, de- posits, 433 Albemarle County, Va., weathering of diurite of, 127 Alexo, Ont., 514 Alkalies in thermal waters, 271 Altenberg, Saxony, tin deposits, 51, 235 Alteration of ore deposits, 124 Altitude, influence on enrichment, 135 Alum, 148 Aluminum, 502 uses of, 503 ore, formed by weathering, 125 Alunite, 71, 148, 502 Alunitie kaolinic gold veins, 255 Amalgam, 401 Amethyst vein, Creede, Colo., 194 Amphibole, 13, 23, 32, 51, 119, 148 Amygdaloidal copper deposits, 395 Analcite, 13, 71, 148 Analyses of fresh and altered diorite, 127 of hot springs, 272 of mine waters, 272 Andalusitc, 23,32. 117, 148 Andradite, 32, 51, 148 Anglesite, 148, 490 Anhydrite, 148, 567 Ankerite, 32, 51, 65, 71, 148 Annabergite, 511 Anna Lee ore chimney. Cripple Creek, Colo., 96 Anorthite, 13, 23, 32, 148 Anthophylhte, 32, 148 Anticlinal deposits, 201 Antimony, 148, 517 Apatite, 13, 23, 32, 51, 65, 148, 577 Apophyllite, 148 Appalachian bauxite deposits, 506 gold deposits, 424 depth of formation, 54 region, secondary sulphide lones in, 141 valley, iron ores, 334 Aquamarine, 23, 148 Aqueo-igncoua deposits, 4 Aragonite, 148 Arfvcdsonitc, 13 Argentitc, 65, 148, 439, 443 Arkansas, aluminum deposits, 505 antimony deposits, 518 diamond deposits, 554 Arsenic, 148, 519 Arsenopyritp, 23, 32, 51, 65, 71, 148. 519 oyGoo»^Ic 590 INI Asbolitc, 515 Ascending hot solutions, composi- tion, 271 origin, 276, 283 Aapen, Colo., 453 Atacnmite, 148, 345, 355 Atlin diatrict, B. C, fractures of, 212 Atmosphere, 124 Autcite, 13, 23, 32, 148 Aurichftleitc, 148, 476 Auriferous conglomerates, 419 Autunite, 526 Aunite, 32 Azurite, 148, 345, 355 Balaklala, Calif., 3S7 Banded ore, 2 Banding, in contact metamorphic depoaita, 36 in replacement deposits, 225 Barite, 65, 71, 148, 557 Baritic fluorite veins, 263 Basal conglomerate, ore of, 98 Base-leveling, influeuce of, on ore enrichment, 135 Basic rocks, magmatic segregations in, 12 Baseic mine, Colo., 97 Bastitc, 148 Bauxite, 65, 71, 88, 148, 502 Bedding planes, 173 Bedding plane deposits, C6, 70, 71, 81, 105, 111, 198 faulta, 105, 111 Bendigo, Victoria, false inverted saddles, 208 saddles, 204 Beryl, 23, 32, 148 Bindheimite, 517 Bingham, Utah, copper deposits, 365 depth of secondarj' zones, 141 wall rock alteration at, 247 BioUte, 13, 23, 32, 51, 148 Birmingham, Ala,, 323 unticlinorium, 320 Bisbee, Ariz., deposit a, 3G7 ore in syncline, 208 Biamite, 520 Bismuth, 23, 65, 148, 520 Bismuthinite, 23, 32, 51, 65, 71, 148, 520 Bismutite, 520 Bituminous matter as a precifHtating agent, 76 Biwabik iron fonnation, 89, 304 Black Hills, S. Dak., gold depooit^ 426 tungsten dcposita, 525 verticals of, 197 Blades of silica, 72 Blind chimney, 201 Blind depomt, defined, 94 Block of oak, deformed, 180 Bonanza mine, Alaska, 394 Bonanzas, 72, 93 Boracite, 573 Borax, 572 Bornite, 23, 32, 51, 65, 71, 148, 345, 357 deposits in sandstone, 77 Bort, 148 Boron compouada, 571 Boulder, Colo., tungsten depouta, 525 Boulder Hot Springs, Mont., 267 Boulder-LeadviUe belt, Colo., 447 Boundaries of replacement deposits, 226 Boumonite, 517 Breccia vein, 188 Breceiated vein, 191 Brecken ridge, Colo., 449 Bremen mine, New Mex., 97 Brewster County, Texas, quicksilver deposits, 500 Brinton, Va., arsenic deposits, 519 Brochantite, 345, 355 Bromine, 566 Bromyrite, 148, 439 Brookite, 143 Brown iron ore, 334 Brucite, 148 [iuilding stones, 533 BuUtrt^, Nev., deposits of, 72 Bullion, Nev,, gamot vein at, 34 Bully Hill, Calif., deposits of, 387 oyGoo»^Ic Bunker Hill and Sullivan lode, Idaho, 193, 495 Buried placers, 416 Burnt umber, 560 Burro Mountain diatrict. New Mcx., 383 Butte, Mont., copper deposits, 357 faulting at, 102, 109 fractures of, 212 mine waters, 159 ore shoots, 97 relation of quartz porphyry dikes and ore deposits, 279 wall-rock alterations, 242 zinc deposits, 486 - zonal distribution of ores, 243, 280 Cable mine, near Anaconda, Mont., 46,466 magnetite ores, 38 Cactus mine, Utah, 236 Cadmium, 529 Calamine, 148, 474, 475 Calaverite, 148, 401 Calcadeu Parish, La., sulphur de- posits, 569 Calcite, 23, 32, 51, 65, 71, 148 Calcitic cinnabar veins, 261 California, antimony deposits, 519 gold belt, 60, 430 quicksilver deposits, 500 Calomel, 148, 499 Calumet copper deposits, Micb., 395 Camp Bird vein, Colo., 455, 456 Cancrinite, 13, 148 Capillary openings, 170 Carbon dioxide, precipitation by escape of, 76 Carbonaceous matter as a precipi- tating agent, 76 Carbonate iron ore, 333 Carinate folds, 118 CamotiU, 527, 528 Carolina tin belt, 523 Cassiterite, 13, 23, 32, 51, 88, 148, 521 veins, 233 Care deposits in limestone, 80 Cavities in replacement depomts, 225 CelestiU, 65, 71, 558 Cement materials, 548 Cements, 542 Cerargyrite, 148, 439, 443 Cerusite, 148, 490 Cervantite, 517 Ceylon graphite deposits, 557 Chalcanthite, 148, 345, 355 Chalcedonic and calcitic cinnabar veins, 261 Chalcedony, 71 Chalcocite, 65, 345, 355 deposited on coal, 78 deposits in sandstone, 77 Chalcopyrite. 13, 23, 32, 51, 65, 71, 119, 346, 357 Chambered deposit, 201 vein, 201, 262 Chamberlin hypothesis, 288 Chamberlin, Tenn,, iron-ore, 330 Chambers, 201 Champion, deposits, Mich., 317 Channels, ore shoots along, 96 Chattanooga, Tenn., iron-ore depos- its, 87. 329 Chemical concentration by weather- ing, 85 Chemical denudation, 287 Chert, 65, 71, 148 Chile, niter, 574 tourmaline veins, 236 Chimneys of ore, 199 Chino Copper Co., deposits, 381 Chi Una copper deposits, Alaska, 394 Chloanthite, 511 Chlorite, 32, 51, 65, 71, 119, 148 Chloritic alteration, 248 in granite, 249 in lavas, 249 Chromite, 13, 23, 32, 88, 148, 507 - Chromium, 507 Chrysofolla, 148, 345, 355 Cinnabar, 499 veins, 51, 65, 71, 148, 261, 499 Circulation of ground water, 75, 132 oyGoo»^Ic Classification of primary ore de- posits, 4, 7 Clay, 535 Clifton, Aril., depoBita of, 376 hydrothemial alteration at, 245 ClimtLtic influences on enrichmeDt, 135 Clinton hematite iron ore, 323, 330 analyses, 330 geaeaia of, 89 Clinton, New York, iron ore. 331 Cobalt, Ont., deposits, 63, 444, 515 cobalt in, 516 fracture pattern, 214 Cobaltite, 65, 71, 148, 515 Coeur d'Alene district, Idaho, deep cone reins grade into inter- mediate uone veins, 60 lead-silver depomts, 493 relation of lead-silver deposits to igneous contacts, 282 wall-Tock alteration, 241 line deposits, 486 Cold solutions, deposits formed by, 4, 6, 74 Colemanite, 573 Collapse during alteration, 220 Colorado uranium deposits, 528 Colorados, 13S Columbite, 23 Combination mine, Mont., Ill Comb structure, 2 Composition of descending thermal metalliferous waters, 271 of magmatic segregations, 13 Compression fractures, 178 Compressive stress, 179 Comstock Lode, Nevada, 70, 71, 467 fissures of, 193 mine waters, 160 Concrete, 544 Conglomerate, ores of, 86, 89 copper deposits, 395 Conjugated fractures, 179, 208 Connections with surface during vein formation, 56 Contact melamorphic deposits, 4, 29 depth of formation, 43 distance from intrusions, 29 Contact metamorphie dep(Mit(i,faDC- tion of mineralicera, 43 minerals of, 44 occurrence, 20 ore of, relation to porosity, 223 rocks altered, 32 rocks caunng, 32 surface enrictunent of, 135 temperature of formation, 45 texture of, 36 metamorphiam, 29-48 age of, 42 at Cable, Montana, 30 at Cananea, Mexico, 31 at Coeur d'Alene, Idaho, 32 at Moreaci, Arizona, 32 at Philipsburg, Montana, 30 at Valsrdena, Mexico, 31 depth of, 43 endomorphism attending, 47 relation to fissuring, 33, 46 Contacts, relation of fissures to, 197 of replacement deposits, 226 Contour of water table, 131 Convection currents in magmas, 10 Cooling cracks, 175 Coordinated fractures, 208 Copper deposits, 71, 149, 345, 354 age of, 351 genesis of, 348 mineral composition, 345, 354 outcrops, 351 production, 348, 347 porphyry deposits, 349 Copper pitch ore 356 Copiwropolis. Calif., 389 Cordierite, 13. 32, 148 Corkscrews, 201 Cornwall, Pa,, magnetite ores, 39 Cornwall tin veins, 52, 233, 234 Coronado vein. Ant., 63, 194 Corundum, 13, 23, 32, 149, 502, 549 gcni, 554 Country rock, 2 Covellite, G.i, 345, 356 Creede, Colo., deposits, 70, 194, 458 handed ore of, 3 hot springs, 265 mine waters, 160 oyGoo»^Ic CretaceouB gold veias, 403 Crevices in Wisconnn siac region, 80 Cripple Creek district, Colo., 70, 434 mine gftBCH, 285 ore chimneys, 96 wall-rock alt«ratioa, 254 w&ter circulation, 278 Crown Point, New York, graphite deposits, 556 Crushing strength of rocks, 115 Cmsti&cation, 2, 235 figure ehowing, 3 Crustified banding, 2 Cryolite, 51, 149, 502, 659, 660 Crystal boundaries, in replacement depouts, 226 Ciyrtal Falls, Mich., 315 Crystallization, force of, 176 Cryatallizers, 21 Cuban la(«rit«s, origin of, 127 Cuprite, 149, 345, 356 Curry iron-bearing formation, Mich- igan, 316 Cuyuna Range, Minn., iron deposits, 90,309 manganese deposits, 510 D Dahlonega mines, Ga., 52, 232, 425 Dale, Calif., deposits, 341 Daubree, experiment of, 176 Deep vein lone deposits, 4, 5, 49 age of, 57 depth of formation, 54 gradation into contact me ta- rn orphic deposits, 61 into pegmatites, 57 into veins formed at moderate depths, 56 mineral composition of, 60 occurrence, 60 siie of deposits, 52 texture of deposits, 52 Deeper circulstion, 1.12 Deer Isle, Maine, schistose ores of, 121 Deerwood Definitions, 1, 2, 3 Deformation, 100 provinces, 101 Dehydration cracks, 176 De Lamar, Idaho, veins, 72, 248 Deposition of secondary sulphides above water level, 143 Deposits, formed at moderate depths by hot solutions, 62 formed at shallow depths by hot solutions, 69 distance of, from intrusive rocks, 63 formed by magmatic Begrega- of deep vein zone, 49 Depth, factor in deformation, 100 of contact metamorphism, 43 of formation of deposits of deep vein tone, 53 of oxidized zone, 140 Desilverizing lead ore, 11 Diallage, 13, 149 Diamond, 13, 23, 552 Diaspore, 502 Diatom aceous earth, 550 Differentiation of m^maa, 10 Diffusion in magmas, 10 DiopBide, 13, 23, 32, 51, 149 Diorite, behavior of, during weather- ing, 127 Direction of movement, 110 Dislocation along faults, 105 Displacement along faults, 104, 105 Disseminated copper ores, hydro- thermal alteration, 244 Disseminated deposits, 67, 188 Dolcoath lode, Cornwall, Pa., 62, 233 Dolomite, 32, 61, 65, 71, 149 Dolomitizalion cracks, 176 Downward enrichment, 130 Drag ore, 109 Ducktown, Tenn., 336, 390, 425 depth of secondary lone at, 141 figure showing oxidation of deposits, 164 mineral changes during oxi-> dation, 165 oyGoo»^Ic Ducktown, Tcnn., mine waters, 159 table showing oxidation of ores, 1S5 Dunnvillc siuidBtonc, 172 Dynamic metaDiorphiBm of ore de- posits, 114 material added, 119 subtracted, 119 Dynamically metamorphosed de- posits, age of, 123 Elagle Mountain, Calif., iron de> posits, 339 Earth, failure, 178 heat gradient, 75 origin, 2S8 rigidity, 288 self compression, 288 shrinkage, 114 volume, 286 water, 286 East Tennessee, iron deposits, 328 zinc deposits, 484 Economic geologist, work of, 1 Eglestonite, 501 Elaeolite, 13, 149 Electrum, 401 Elements of faults, 105 Elkhom, Mont., deposits, 206 Elongation during dynamic meta- morphism, 117 El Paso, Texas, tin deposits, 236, 524 Ely greenstone, 321 Ely, Minn., iron deposits, 322 Ely, Nevada, copper depositB, 379 Embolite. 439 Emerald, 23, 32, 149, 554 Emery, 13, 23, 32, 149, 550 Enargite, 65, 149, 345, 357, 519 End producta of weathering, 84 Endom Orphic changes in contact metamorphism, 47 Enduring surface, 216 Encampment, Wyo., 389 c\tent of chatcocite zones at, 141 pi^gmatitcs grade into quartz England, tin deposits of, 235 Enricbment, diagram showing im- portance of, with respect to several metals, 167 general features, 124 silver deposits, 441 sulphide, 130 Knatatite, 579 Eotian deposits, 8 Eolian gold deposits, 416 Epidote, 33, 51, 119, 149 Epigenetic deposits, 4 structural features, 184 Equidimensional deposits, 199 Erosion, influence of on enrichment, 136 of lodes, estimate of amount, 153 Erythrite, 515 Erzgebirge uranium deposits, 526 Eureka, Nevada, 446 Eutectics, 18 Experiments, in compression, 121 in contact metamorphism, 44 in precipitation of metals, 154 in solution of metals, 154 Fahlband, 190 False inverted saddle, 207 saddle, 203 Famatinitc, 357 Famcombe Hill, Colo., 449 Fault, definition, 103 dip, definition, 103 fissure, definition, 184 vein, 186 muzaic, 107 patlcrns, 110 BtriiB, 107, 110 strike, definition, 103 Faulted scgiiicnta. search for, 107 Faulting. 101 combined with flowage, 118 of ore deposits, 102 Riulla, deposition in, 192 mineralized, in hmestone, 194 Fayalitc, 149 oyGoo»^Ic Feldapars, 502, 640 abrasive, 550 Ferberite, 524 Fertilisers, 575 Fierro, New Mexico, 339 I^BSures, 184 ■iie of, 1S5 Flat Kiver, Mo., deposits, 491 Flato and pitches, 81, 190 FlftxBeed ore, 329, 331 Florence district. Wis., 315 Flowt^e, lone of, 101 of minerals compressed in tubes, 121 of ore deposits, 113 Fluid inclusions, in igneous rocks, Fluorite, 13, 23, 33, 51, 66, 71, 149, 529 deposited in veima near hot springs, 266 Fluorite-barite veins, 263 Fluoritic tellurium-adularia gold veins, 254 Folding, of ore deposits, 102, 113 in sone of 6owage, 1 01 in Kine of fracture, 101 Foothill copper belt, Calif., 388 Footwall, 103 Force of cryBtaUieation in vein formation, 55, 176 Forsterite, 33, 149 Fossil ores, 89, 329, 331 Fourche Mountain aluminum depos- its. Ark., 503 PVactional crystallization in mag- mas, 10 Fracture, systems, 208 tone of, 101, 115 Fractured zone, 187 Fractures, formed by compression, 178 on anticlines, 181 is synclines, 207 tennonal, 180 Fracturing, by pressure, 179 Fragments in replacement deposits, 227 >EX 595 Franklin Furnace, N. J., deposits, 208, 487, 511 Franklinite, 33, 149, 290, 470 Freibe^ite, 444 Frisco district, Utah, 406 Fuller's earth, 539 Gahnite, 51, 149 Galena, 15, 23, 33, 51, 65, 71, 149, 489, 490 Gangue, 2 miaeral, 2 Gap, 106 Garoet, 13, 23, 33, 61, 88, 117, 149, 549, 556 veins, Dahlonega, Ga., 53 Eones, 39 Gametiferous gold veins, 232 silver-copper veins, 232 silver-lead veins, 233 Gamierite, 511 Gas, in lavas, 286 in metal mines, 285 Gash vein, 189 in Wisconsin, 30 Gay-lussite, 149 Gems, 552 Geological Society of America, re- port of committee on faults, 102 Georgetown, Colo., relations of igne- ous dikes and ore deposits, 279 Gersdorffite, 511, 512 Gibbsite, 149, 502 Gilpin County, Colo., gold-silver deposit a, 450 pitchblende deposits, 526 Glacial deposits, 8 gold deposits, 416 Glaciation, relation of enrichment to, 137 Glass sand, 551 Glosses, 19 Glauconite, 32, 149, 290 Globe, Ariz,, deposits, 371 range of chalcocite ore, 141 Goethit«, 290 oyGoo»^Ic Gogebic range, Mich., 311 length of, 89 Gold, 13, 23, 33, SI, 65, 71, 88, 149 depoBita, 401 Hge of, 403 concentration in oxidised »t,34 410 in hot spring deposits, 268 (lodes, relation to placers, 415 ores, genesis of, 402 tenor of, 401 placers, 87, 408, 411 minerals in, 414 relation to gold lodes, 415 Goldfield, Nev., 70, 71, 437 fracture patterns, 213, 214 source of metal-bearing waters, 279 vall-rock alterations, 256 Gold-silver adularia veins, 248 Goslarite, 149, 474 Gossan, 138 Gossan Lead, Va., 336 Gouge, 2 Graben, 107 Gradient of earth's heat, 75 Granite, 533 Granite-Bimetallic mine, Mont., secondarj' ore of, 146 Graphic intergrowths of sulphides, 147 Graphite, 13, 23, 33, 51, 556 Grass Valley, Calif., deposits of, 433 wall rock alteration, 239 Grecnalite, 290. 307 Greenoekitc, 149, 529 Greisen, 235 Grindstones, 5-18 Grooves, 107 Grossularite, 33 Groundwater. 131 circulaliiiii, 75 Guano fertilizer, 576 Gui ■, am Gypsum, 149, 5<>7 ferliliicr, 570 Hachita, N. M., garnet vi Haile mine, S. C., 426 Hailey, Idaho, wall rock alteration, 240,241 Halite, 149 Hanging wall, deBniUon of, 102 Hanover, N. M., deponts of, 339 HaQynite, 13, 149 Hartville, Wyo., iron ores, 338 Hausmanntte, 508 Huel Green mine, Wia., 79 Headlight vein, Mont., Ill Heat, gradient of earth, 75 transfer in earth, 289 Heave of faults, 105 Heavy residuals in placers, 90 Heavy silicate loaes, 39 Hedley, B. 0., contact metamorphic depoeita, 32 Hematite, 13, 23, 33, 51, 88, 149, 290 depout« of western United States, 338 Hibbing, Minn., deposits of, 302 Homcstakc mine, S. D., 426 Horizontal shear, 181 Hornblende, 13, 23, 33, 51, 149 Horse, diagram showing, 103 Hope mine, Mont, 202 Horst, 107 Horn Silver mine, Utah, 497 Hot springs, 265, 275 analyses of waters, 265 Anaconda, Mont., 267 Boulder Hot Springs, Mont., 260 Norris Geyser Basin. Mont., 267 Ojo Caliente. New Mexico, 266 Wagon Wheel Gap, Colo., 265 dciiosits, 263 smelted for gold. 268 Hot waters of Wagon Wheel Gap, Colo., 265 Hubnerile, .'524 Humites, 33, 149 oyGoo»^Ic Hurier, Wis., deposita, 311 Hydrc^en sulphide, generatitm with acid, 158 precipitation by, 76 Hydrolyaia of ferric sulphate, 154 Hydrometamorphiam, 123 Hydroaphere, 124 Hydrothennal alUration, 3, 230, 231 naotii^ in dynamically meta- morphoBed depoaita, 122 widths of Eonea of, 221 Hydrous minerals in igneous rocka, 284 Hydrotincite, 149, 474 , deposits of, Is erf, 94, Idaho Springs, Colo., 450 mine waters, 160 Igneous emanationa, 12 intrusion, mechanism of, 28fi locka, gases in, 286 metals in, 287 Umenite, 13, 23, 33, 51, 149, 290, 5I3 Ilvaite, 33, 149 Imbricating blades of siUca, 73, 144 Incompetent beds, behavior of, IIS Infusorial earth, 550 Int«rgranular spaces, 172 Intermediate depths, deposits formed at, 62 vein zone, minerals of, 65 Intersections, dikes and fissures, 66, 199, 200 ore shoots along, 96 Intrusion, mechanism of, 289 Intrusive rocks, relation to ore de- posits, 283 Inverted saddles, 207 Inyo County, Calif., deposits, 563 lodyrite, 439 Iron, 13, 290 bacteria, 294 deposited in lakes and seas, 294 hat, 138 in earth, 291 migration during weathering, EX 897 Iron, per cent, of, in earth, 290 production in United States, 297 Iron Age deposit, Calif., 341 Iron ore, deposits, 290 formed by weathering, 125 formed by weathering of ' aer- pentine, 128 genesiB of, 291 Iron Mountain, Mi 86,341 Iron Mountain, Wyo., 343 Iron onide in outcrops, 139 Iron River, Mich., 315 Iron Springs, Utah, depowU, 61, 388 Ironwood iron-bearing formation, 311 Irregular fracture patterns, 212, 213 Ishpeming deposits, Mich., 317 Isodiametric deposits, 199 J Jadeite, 33, 149 Jantesonite, 517 * Jarilla, New Mex., garnet vein at, 34 Jaspurite, 515 Jerome, Ariz., 385 Joptin, Mo., region, brecciated ore, 82 cadmium in ore, 529 ore shoots, 97 Juneau, Alaska, deposits, 433 Kalgoorlite, 71, 149 Kant hypothesis, 287 Kaohn, 71, 88, 149, 502 Keweenawan baaic cffusives, 314 copper deposits, 395 Keweenaw Point veins, Mich., 260 Kennedy mine, Cuyuna Range, Minn., 90 Kennicott copper deposits, Alaska, 394 Kimberly diamond depoeite, 553 Krennerite, 401 oyGoo»^Ic KuDsite, 555 Kyanite, 23, 33, 140 Long slender deposits, 190 Ludwigite, 33 L& Colorada, Mexico, graphite de- posits, 556 Ladder veins, 187 Lake City, Colorado, deposits of, 457 Lake Superior region, copper de- posits, 70, 395 formations, 300 iron deposits, 207, 298 synclinorium, 298 Lake Valley district. New Mex., sec- tion of, 22$ La Motte mine, Mo., 491 Lancaster Gap, Pa., nickel deposits of, 515 Land sediments, 7 Laplace hypothesis, 287 La Plata Mountains, Colo., 457 Last Chance mine, Bingham, Utah, wall -rock alteration, 247 Lateritea, origin of, 127 Laurile, 516 Lead, 149, 489 Leadhillite, 149 Leadvillc, Colo., 451 Lead-zinc deposits, segregation by weathering, 476 Ledge, 186 Lena, 190, 89 Lcpidolite, 23, 51, 149 Leucite, 13, 149 Level of ground water, 131 Lila C. borax mine, Calif., 573 Lime, 545 Limestone, analysis of before and after contact Limonite, 88, 149, 290, 293 Linden, Wis., deposits, 81 Lithium minerals, 542 Lithophysa;, 284 Lithoapherc, 124 Loekhatt vein, 52 Lode, 184, 186 Magmatic differentiation, 9 of rocks, 0, 10 Magmatic segregations, 4, 5 general features, 9 occurrence, 11 ore Bhoot« of, 94 rock fragments in, 9 shape, 13 teuture, 9, 14 Magnesite, 71, 149, 579, 580 Magnesium minerals, 579 Magnet Cove, Ark., rutile deposita, 532 Magnetite, 13, 23, 33, 67, 65, 88. 149, 290 -bearing veins, 60 bodies of contact metamorphic origin, 38 ore. New Jersey, 337 New York, 337 Pennsylvania, 337 Malachite, 149, 345, 355 Mallardite, 508 Manganese, 508 Cuyima range, Minn., 510 deposits formed by cold solu- tions, 79, 80 in Blue Ridge, 510 in gold deposits, 405 in outcrops, 139 use and production, 509 Manganitc, 149, 508 Manhattan, Nev., deposits, 72 Marcasite, 71, 149, 290 Marquet(« district, Mich., 317 synclinorium, 319 Mary Mine, Tenn., aection of, 202 Marysville, Mont., 72 Massicot, 489 Mayari ore deposits, Cuba, 128. 129 Meadow Lake district, Calif., 236 Mechanical concentration, by weathering, SS oyGoo»^Ic Medicinal waters, 588 Meerschaum, 579, 580 Metaconite, 149, 345, 355 Mclanterite, 290 MeliUte, 13, 149 Mendota mine, Colo., ore of, 191 Menominee district, Mich., 31S Mercury, 149, 499 in hot spring depoaite, 262 Mesabi range, Minn., depoeiteor, 301 contact metamorphiam in, 37 length of, 89 Metallogenic epochs, 269, 270 provinces, 2, 269 Metamorphism, of Modoc formation, Morenci, Ariz., 39 of ore deposits, 114 Metasomatic proccsHea, 218 Metasomatism, in vein formation, 218 in sulphide enrichment, 165 Meteoric waters, depoaite formed by, 75 Metropolitan district, Mich., 315 Miami, Ariz., deposits of, 371 Miami, Okla., deposits of, 477 Miarolitic cavities, 9, 174 Mica, 540 Michigan, copper depodta, 70, 395 veins, wall alteration, 260 salt deposits, 563 Microcline, 23, 149 Microscopic particle, minimum size of, 220 Middle zone deposits, 4 Milan mine. New Hampshire, ores of, 116. 191 Millerite, 149, 611, 512 Millstones, 548 Minasragra, Peru, vanadium de- posits, 529 Mine Hill deposits, N. J., 487 Mine waters, 272 analyses, 159, 160 changes in depth, 162 composition of, 158, 160 general character, 161 precipitates from, 162 Mineral associations, 230 Mineral associations, in contact metamorphic deposits, 32, 44 fertilizers, 575 paints, 560 waters, 587 Mineralizers, 21, 289 activity in deep vein zone, 57 elements of, in contact meta- morphic ores, 43 Minerals, lists of, 13, 23, 32, 33, SI, 65, 71, 88, 119, 148 cold solution deposits, 80 in magmatic seftregations, 13 of sedimentary deposits, 87 primary and secondary, 148 stable, during weathering, 126 Minium, 489 Mississippi Valley zinc and lead de- poMts, 74, 76 Missouri, barite deposits, 558 iron deposits, 342 lead deposits, 491 zinc deposits, 477 Moderate depths, deposits formed at, 4, 6, 62 composition, 79 general features, 62, 74 minerals of, 65 76 shape, 80 texture, 81 Molecular replacement, 220 Molecule, siie of, 220 Molten magmas, 284 Molybdenite, 13, 23, 33, 51, 65, 71, 119, 149, 530 Molybdenum, 530 Molybdie ochcr, 530 Molybdite, 149, 530 MonaziU, 13, 23, 33, 88, 149, 584 Monte Cristo, Wash., deposits of, S19 Montroyditc, 501 Morenci, Ariz., 376 chalcocit£ ore, 144 contact zones, 39 magnetite ore, SS] wall-rock alteration, 246 oyGoo»^Ic 600 im Mortar, 544 Mother Lode, Calif., 430 Mount Mica, Paris, Me., 95 Moyie, B. C, 233 Muscovite, 13, 23, 33, 51, 65, 71, 119, 149, 540 Mysore, India, deposits, 205 N Nacimiento, New Mexico, copper depoeits, 78 Native copper, 354 deposits of, 70, 260, 395 Native gold, 401 Nebular hypotbesia, 288 Negaunee iron-beariug formation, 317 Nephelin, 13, 149, 502 rocks, weathering of, 505 Nevada City, Calif., deposits of, 432 wall-rock alteration, 23S Nevada Consolidated Copper Com- pany, depomts, 379 New Caledonia, 515 Niccolite, 65, 149, 511 Nickel, 511 uses and production, 512 Nitrates, 574 Nodular ore, 145 Nomenclature of faults, 102 Nonesuch copper belt, Mich., 400 Normal faulta, 106, 107 Norway-Aragon area, Mich., 317 Noselite, 13, 149 Nova Srotin, saddles ol, 206 O Oblique fault, 106 Ocean, age of, 287 composition of, 561 Ocher, 661 Octahcdritc, 140 OfFsct of faults, 106 Oilstones, 549 Ojo Caliente, New Mexico, deposits, 263, 260 Olivine, 13, 33, 149, 290, 579 Oolitic ores, 89, 145, 331 Opal, 65, 71, 140 Openings^ along uiticlinea, ISl in rocks, 170, 184 Opbit district, Ctdif ., deposits of, 237 wall rock, alteration of, 238 Ore, definition, 1 deposits, definition, 1 defonnation o(, 100 faulting and folding, 102 mineral, 2 shoots, 93 Organic matter as precipitating agent of metala, 77 Orientation, of fragments in replacft- mcnt deposits, 223, 227 of ore bodies during dynamic metamorphism, 117 Origin of magmas, 287 Orpunent, 65, 149, 519 Orthoclase, 13, 23, 33, 51, 65, 149 Ottrelite, 117, 149 Ouray, Colo., deposits of. 456 Outcrops, above sulphide deposits, 138 of copper deposits, 351 of ore deposits, 215 Overlap, 106 Overlapping lenses, 7, 190 Overthrust, 107 Oxidized sone, depth of, 140 Oxidation, of pyrite, 154 of sulphides, order of, 163 PiiciBc coast gold deposits, 4 Pftigcite, 33 Pandermite, 573 of contact metamorpbic ores, 37 of metamorphosed deposits, 120 of secondary ores, 166 Parallel fracture systems, 21 1 Park City, UUh, deposits of, 400 Pay streak, 93 Pearcite, 439, 444 Pegmatite veins, 4, 5 oyGoo»^Ic Peg matites, 5 banding in, 25, 26 composition of, 23 general features, IS gradation, into deep Eone veins, 57 into gold veins, 282 into quart! veins, 26 occurrence, 22 ore shoote of, 05 outline of characteristics, 18 shape of, 24 size of, 24 texture of, 2S Penokee-Gogebic range, 311 length of, 89 PentUndite, 13, 65, 511, 512 Peridotite, 556 Permeability of rocks, 135 Petsite, 65, U», 401 Philipeburg, Montana, Bilver-gold deposits, 464 contact metamorphism at, 41 manganese deposits, 511 similar ores in different rocks, 280 sketch showing veins, 63 veins, depth of formation, 54 wall rock alteration, 248 Phlogopite, 541 Phosphate rock, 576 Picotite, 13, 33, 140 Pilot Knob, Mo., deposits, 341 Pinetucky, Ala., gold deposits, 425 Pisolitic ore, 145 Pitchblend, 526 Pitches, 81, 190 Placere, 7, 87, 411 gold, 408 shape of, 89 Placervillc, Colo., uranium deposits, 627, 529 vanadium deposits, 527, 529 Planetessimal hypothesis, 288 Platinum, 13, 33, 51, 65, 71, 88, 516 Plattnerite, 489 Plumas County, Calif., graphic ore of, 147 Pocket, 93 >EX 601 Pod, 190 Polianite, 608 Polybasite, 65, 71, 149, 439, 444 Porcupine, Ontario, 422 Porphyritie minerals formed during dynamic metamorphism, 117 Porphyry copper ores, 67, 360 Porosity of altered material, 223 Potash salts, 565 Potential of minerals, 156 Potsdam ores, 8. EMt., 429 Pre-Cambrian gold deposits, 403 Precious stones, 552 Precipitation, caused by organic materials, 76 near the surface, 72 of metals, 76, 164 of sulphides above water level, 143 Pressure of solutions, 177 Primary deposits, 4 diagram showing genesie of, 91 Primary openings, 171 Primary ore, influence of on sec* ondary sones, 168 ore shoots, 93 Propylitic alteration, 249 and sericitic alteration compared, 250 Protore, 1 Proustite, 65, 71, 149, 439, 444 Pseudomorphs, 224 in secondary ore, 143, 146 Psilomelanc, 88, 149, 588 Pulpstone, 548 Pulsations of ground wat«r. 134 Pumice, 174 Puzzolan cement, 546 Pyrai^yrile, 65, 71, 149. 439, 444 F^rite, 13, 23, 33, 51, 65, 71. 149, 571 oxidation of, 145, 154 Pyrolusite, 88, 149, 508 Pyromorphite, 149, 490 I^rrhotite, 13, 23, 33, 51, 290 gold veins, 60 lead veins, 60 oyGoo»^Ic QuartE, 13, 23, 33, 51, 65, 71, 88, 149, 551 bodies elongated during dy- namic metAuoiphiam, 117 Quicksilver in hot spring deposits, Radial fracture patterns, 212 Radium, 526 Kammelaberg deposits, Germany, 121, 122 Rtind gold deposits, 420 Ray, Ariz., deposits of, 375 Realgar, 65, 71, 519 Recrystallization of minerals during dynamic metamorphism, 117 Redcmptioii iron mine, near Philips- hurg, Mont., 38 Reef, 186 Regional mctamorphism of ore de- posits, 114 Relief, influence of, on enrichment, 135, 136 Reopened veins, 190 Replace men t, 3 during sulphide enrichment, 166 in Black Hills, S. D., 229 mechanism of, 218 veins, 3, 223 Replacement deposits, 1^23 boundaries of, 226 recognition of, 223 Republic Trough, Mich., 317 Residual deposits, 7 Residual minerals, of trcatliering, 88 in replaced rocks, 229 Hesiduary ores of Iron Mountain, Mo., 86 Reticulated vein, 188 licverae faults, 106, 107 deposition in. 105 ltI.oilochn.siU\ 23, 0.5, 71, 149, 508 Rhodonite, 23, 33, 65, 71, 149, SOS Ribbons of ore, 199 faulting of, 112 Rico, Colo., 457 ore shoots of, 97 Riddle, Ore., 515 Riebeckite, 13, 149 Roberts mine, Linden, Wis., 81 Rock flowage, 101 structure, influence of, oa &»• suring, 196 Rockwood iron oie, 87, 330 RoBcoelite, 528 RoBsland, B. C, 232 Rotation during faulting, 103 Rotational strains, 179 Ruby, 23, 33. 149 Ruby Trust mine, Qranby. Mo., 78 Run, 190 Rutile, 13, 23, 33, 51, 88, 149, 531 Ryerson mine, Morenci, Arii., on of, 144 Saddle reef, 201 Saddles, 203 origin of, 204, 205 Saint Eugene mine, B. C, 233 Salt, 561, 562 domes, 564 Samarskite, 526, 532 San Francisco region, Utah, 236, 496 San Juan region, Colo., 454 San Luis Obispo region, Calif,, chromite of, 508 Santa Rita, New Mexico, 381 Sapphire, 13, 23, 33, 149 Seapolite, 23, 33, 51, 149 Sfhcelite, 23, 33, 51, 524 Schistose sulphide ores, 116 Schistosity, of metamorphosed de- posits, 120 relation of fissures to, 197 Schlegel milch. South Carolina, veins, 55 Schlicren, 9, 14 Schuermann's series, 157 Scour and fill, 413 oyGoo»^Ic Scythestonea, 649 Sea, age of, 28 water, amount of, 286 compoBitioD of. 561 precipitation of, 562 Secondary deposits, 4 criteria, 150 Secondary enrichment, 124 of copper, 352 of gold, 405 of silver, 441 Secondary minerals, 148 Secondary openiiigs, 175 ore shoots, 99 textures, 143 sulphide lone, position and ex- tent, 140 relation to water level, 142 -veinlets in sulphide ore, 145 zones, influenced by primary ore, 168 Sedimentary deposits, 4, 6, 84, 87 general features of, 84 minerals of, 88 ore shoots of, 98 shape, 89 tration, 84 Segments, search for, 107 Segregated veins, 7, 118 Selenite, 149 Selenium, 531 Senarmontite, 517 Separation, by faults, 105 Sericite, 33, 51, 65, 71, 149, 502 Sericitic alteration and propyiitic alteration compared, 250 calcitic gold veins, 237 copper veins, 244 copper-silver veins, 242 silver-gold v i, 242 Serpentine, 149, 579, 581 Sevier County, Ark., depositH, Seward Peninsula, Alaska, tin de- ponits, 524 *EX 603 Shallow depth, deposits formed at, 4, 6, 69 minerals of, 71 Shasta County, Calif., deposits of, 386 pegmatites grade into gold bearing quartz veins, 27 Shear zone, 189 Sheeted zone, 66, 188, 189 Shift of faults, 105 Shoots of ore, 93 Shrinkage, by cooling 176 cavities, 175 of earth, 114, 178 Sicilian sulphur deposits, 570 Siderite, 51, 65, 71, 290 Sideritic lead veins, 240 Sienna, 560 Silication by contact metamorphism, 38 Sillimanite, 33, 140 Silver, 13, 51, 71, 439, 443 Silver City, Idaho, wall rock alter- ation at, 248 Silver Peak, Nev,, deposits of, 58, 59 gold deposits, 282 pegmatites grade into gold deposits, 27 Silver Plume, Colo., deposits of, 450 Silverton, Colo., deposits of, 455 Slags, 18 Slate, 535 Slender deposits, 199 Slickensides, 108 Slip of faults, 105 SmalUte, 515 Smithsoaite, 149, 474 Sodalite, 13, 149 Sodium sulphate, 560 Solution cavities, 175 Solution, of gold in placers, 414 of metals, 154 of salt and water, behavior of, 19 Sorct's principle, 10 Soudan formation, 322 Sources of ascending thermal metal- liferous wateT^ 271, 274 oyGoo»^Ic 604 JNl Southeast Missouri lead deposila, 491 Southern Appalachian gold deposits, 424 Southern Cross, Mont., deposits of, 466 weathering at, 210 Spaces along fissures, 185 Specularite, 13, 23, 33, fil, 149 SperryUte, 616 SpessartiU, 508 Sphalerite, 474, 475, 476 Sphenilites, 284 Spinel, 13, 23, 33. 51, 149, 555 Spodumene, 13, 23, 149 Spokane, Wash., tin deposits, 523 Springs, 265, 266, 267 Stable minerals, 88 residual minerals, 126 Stagnant water zone, 133 Stalactites in oxidised aone, 143 Stasafurt salt deposits, 564, 566 Stauffer borax deposits, Calif., 573 Stannite, S21 Stauralite, 33, 117, 149 Steamboat Springs, Nev., 262 Steatite, 149 Stephanite. 65, 71, 439, 444 Stibnite, 51, 65, 71, 517 Stilbite, 71 Stirling Hill deposits, N. J., 487 Stockwerk, 188 Stratton's Independence mine, Colo., 435 Strength of rooks, 115 Stresses in earth, 289 openings formed by, 177 Stria, 107, 110 Stromcyeritc, 71, 149 Structure of openings, 184 Structures, influence on lissuring, 196 Suhcapillary openings, 170 sheet openings, size of, 220 Submicroscopic spaces, 174 Subsidiary fractures, ore in, 165 Sudburj- nicko! deposits, genesis of, 84 Sudbury, Ontario, 12, 513 Sulphates, solubilities of, 1£6 Sulphide enrichment, 130, 352 of copper, 362 of nlver, 441 Sulphides, soIubiUtiee oi, 157 Sulphur, 149, 569 uses of, 571 Sulphur Bank, Calif., 293 Sulphuric acid, S71 Supercapillaiy openings, 170 Superficial alteration, 124 enrichment, gold, 405 Surface connections, during vein for- mation, 50 Sweetwater, Tenn., iron ores, 336 Syenite, weathering of, 505 Sylvanite, 66, 71. 401 Symmetrical banding, 2, 3 Synclinal deposito, 207 Syngenetic depoaite, 4 Synthetic experimraits, in contact metamori^iism, 44 Tabular body, 2 Taconite, 307 Talc, 149, 679, 680 Tamaulipas, Mex, contact meta- morphism at, 40 Tanlalitc, 532 Tantalum, 632 Telluride, Colo., depooita of, 456 Tellurides, 51, 65, 71, 149 of gold, 410 of silver, 439 Tellurium, 531 adularia veins, 254 gold veins, 254 Temperatures, of formation uf con- tact metamorpfaic deposits, 45 of formation of pegmatites, 27 Temporary surface. 216 Tenabo Peak, Nev., section of, 228 Tcnnantitc, 65, 71, 346, 357, 439, 444, 519 Tennessee copper depouts, 390 Tennessee valley iron ore deposits, oyGoo»^Ic Tenorite, 149, 346, 355 Tennonal fractures, 180 Tephroite, 808 Terlinguft district, Teras, 500 Terlinguite, 601 Tertiary gold depoeita, 404 Tertiary iron OTea of Texas, 332 Tetrahedrite, 66, 71, 346, 367, 439, 444, 617, 620 Texas iron ores, 332 Texture of contact roetamorphic depomts, 36 Textures of secondary ores, 143 Thermal waters, 271 Thetford, Que., asbestos deposits, 682 Throw of faults, 105 Thrust of solutions in vein forma- tion, 55 Thuringite, 71 Ticonderoga graphite deposits, 556 Tidal stresses in solid earth, 289 Tiger-Poorman vein, Idaho, 60 Time element in enrichment, 136 Tm, 149, 521 enrichment of, 522 production of, 522 uses of, 622 Tintic, Utah, deposits, 462 Eonal arrangement of ore de- posits, 280 Titaniferous iron ores, 343 Titanite, 13, 33, 149 Titanium, 531 Tombstone, Ariz., deposits at, 203 Tonopah, Nevada, deposits, 70, 470 faulting at, 110 sources of water that deposited ores of, 279 wall-rock alteration at, 250 Topaz, 13, 23, 33, 51, 149 Topographic exptesaion of deposits, 215 Torbemite, 526 Torsion, effect on glass, 183 Torsional fractures, 182 Tourmaline, 13, 23, 33, 51, 565 vebs, 236 Tower, Minn., iron deposits, 322 EX 605 Traders iron-bearing formation, 310 Trail Creek, B. C, 232 TremoUte, 33, 51, 57ft Trenton iron ore, 87 Tridymite, 13, 14S Tripoli, 549 Troughs, 207 True fissure veins, 81, 186 Tungsten, 524 Tungstite, 524 Turgite, 149, 290 Turquoise, 149, 555 Tuscarora, Nev., deposits, 70 Tyuyamunite, 526 U Ulexite, 673 Umber, 560 Undei%round water, movements of, 132 United Verde Co., Aris., 385 Uralite, 149 Uraninite, 526 Uranium, 620 ores in sandstone, 78 Utah Copper Company deposits, 366 Utah, ore deposits, 281 relation of different deposits to different intruaives, 281 Uvanite, 626 Vadose circulation, 132 Valencianite, 149 Valentinite, 517 Vanadium, 528 ores in sandstone, southwest Colo., 78, 528 uses of, 529 Variations in widths of v< Varicite, 556 Vein, 2, 186 breccia, 188 filUng, 4 gash, 18ft ladder, 187 ore shoots in, 95 B,227 oyGoo»^Ic 6oe im Vein, tcopcned, 180 reticulated, 188 walla, 2 Vesuvianite, 33, 149 Virgilina district, 147 Virginia, barite deposits, 558 iron ores, 335 Virginia Minn, depoaita, 302 Vennilion Range, Mich., 321 Vertical separation, by faults, 105 Verticals, 197 Black Hills, S. 