INDEX. 



1279 



Sierra Nevada, disintegration of rocks in, depth 



of 530 



gold ore of, origin of. .. 1084 



injected granite of 647 



Silica, amount of, annually removed from soil 486 



colloidal, silicification by.. _ 540,547 



crystallization of, form of, dependence of, on 



depth 185 



deposition of, forms of 622-623 



in earth's crust 934,937,938,960-962 



in grain and straw 454 



in mineral-spring waters... - 572 



in solutions, state of 67 



in underground water, large amount of, where 



vegetable matter is abundant . _ 476 



liberation of, byactionof carbon dioxide 480 



solubility of 516-517 



solution and precipitation of . . . 540, 547, 848-849, 960-961 



source of, for marine organisms _ _ 848 



Silica family, deposits composing 847-853 



See also Silicate rocks; Silicates. 



Silicate of zinc, formation of 480 



Silicate rocks, origin of, from limestones and dolo- 

 mites 822-823 



Silicated marbles, origin of 820-821 



Silicates, action of carbon-dioxide solutions on 475- 



476,611 



alkaline reactions of certain solutions of. 86-87 



alterations of, summary _ 352-354 



anhydrous, deposition of _ 625-627 



behavior of, on dissolution 67 



car Donation of _ 175-176 



cementation by 621,634-636 



character, occurrence, formation, and altera- 

 tions of _ 246-354 



chemical relations of , to carbonates 173-177 



deposition of, conditions of 625-627, 1129-1132 



hydrolysis of 86 



hydrous, alterations of 519 



deposition of 625 



solubility of , increased by pressure . 78 



Silication, alterations produced by 406 



definition of 168,205 



depth and pressure at which carbonation re- 

 places 180-181 



examples of 218-219 



extent of, as compared with extent of carbona- 

 tion.. 971-972 



illustrations of. __ 169 



in zone of anamorphism, discussion of 677-679 



of carbonates, discussion of _ 176-177 



volume results of 177 



Silication and decarbonation, alterations produced 



by 407 



Silicationand dehydration, alterations produced by. 407 

 Silication and hydration, alterations produced by.. 405 

 Silication, carbonation, and hydration, alterations 



produced by 399 



Silication, dehydration, and decarbonation, altera- 

 tions produced by 407 



Silication, hydration, and decarbonation, alterations 



produced by .... r _ 408 



Silication, oxidation, and decarbonation, alterations 



produced by 408 



Siliceous sinter, deposits of 550,848 



Silicic acid, acids replaced by 205 



chemical activity of, at depths 67 



colloidal, dehydration of 616-617 



Silicic acid, oxides, uniting with 205 



presence of, in ground waters __ 93 



production and deposition of 540 



replacement of carbonic acid by. _ 94 



replacement of carbonic acid by , volume changes 



resulting from _. 93 



work of , in ground-water solutions 93 



Silicification, definition of . _ __ 205 



example of _ _ _ 646 



of calcareous formations, example of 850 



Silicon, chemical relations of, to carbon, discussion 



of-- — — 173-177 



in earth's crust 934,936,959-962 



replacement of carbon by, discussion of _. 175-177 



Silicon-bearing minerals, deposition of 628 



Silicon compounds, specific volumes of, compared 

 with volumes of similar carbon com- 

 pounds _. 175 



Silicon dioxide, replacement of, by carbon diox- 

 ide 173-177 



Sillimanite, alterations and alteration products 



of _ 318-319,374,392,402,403 



chemical and physical constants of 200,316 



occurrence of 316-317 



sources and modes of formation of 223, 224, 225, 



232, 317, 339, 342, 372, 379, 381, 383, 396, 406, 407 



Silver, association of, with base metals 1166-1169 



native, genesis of. _ 1167-1168 



precipitation of 1082,1100-1101 



salts dissolving 1075 



solution of _. _._ 1099-1100 



solution of. by ferric sulphate, equation showing 1099 

 Silver Age mine, Idaho Springs, Colo., ore shoots 



near intersecting fractures at 1227 



Silver-lead deposits of Aspen district of Colorado, 



origin of 1084 



Silver sulphate, reduction of, to silver sulphide, 



equation showing reaction for 1111 



Slate, definition of _ 778-779 



photomicrographs of_ __ 902 



Slate-graywacke, deposits of, character and origin 



of. 



Slate-pelite, deposits of, origin and character 



of 894-904 



Slates, chemical analyses of __ 895,896 



deposits of, origin and character of 892-904 



minerals of, development of _ 898 



Slichter, C. S., diagrams cited from, showing open- 

 ings in rocks _ /__ 132,133 



on arrangement of particles of mechanical 



sediments 596 



on flow of ground waters 572, 576, 577, 582, 584, 1207 



on flow of water through capillary tubes 139-140 



on most compact arrangement of molecules 362 



on openings in rocks 125, 131-132, 137, 863, 864 



on pressure of underground water _ 587 



Slope, effect of, on metamorphism ._ 41 



Smaragdite, source and mode of formation of. 274, 372, 381 

 Smith, F. C, on tellurides associated with Potsdam 



gold ores of Black Hills.. 1119 



Smith, J. G , on penetration of soil by alfalfa 445 



Smith, W. N., acknowledgments to __. 29 



Smithsonite, occurrence and associations of 1147, 1150 



sources and modes of formation of _ 828,1147 



Smuggler Union mine, San Juan district of Colo- 

 rado, ore shoots produced by second- 

 ary fracture in.. __ 1228 



water in 1132 



