1260 



INDEX. 



Page. 



Glass, alteration of, minerals produced by 251 



devitrification of, phenomena of._ _ 247-252 



heat and volume relations of. 251-252 



natural, occurrence, and alterations of 246-352 



solubility of , in water .. 79» 



80, 112, 630, 637, 692, 723, 740, 749, 750 



strain in, example of . . . - - - - - 691 



Glauconite, character, occurrence, and alterations 



of_ 



351 



chemical and physical constants of. 197,351 



Glaucopkane, chemical and physical constants of- 197, 283 

 occurrence, sources, and modes of formation 



of. 



Gmelinite, character and occurrence of .. 331-333, 



Gneiss, definition of 782-783 



features of - . 782-783 



losses in, by weathering, analysis showing 508,515 



metamorphic, igneous, and sedimentary rocks 



often combined in 911-912 



minerals of, development of 899 



photomicrograph of 902 



Gneiss-arkose, depositsof, originand character of . 875-876 

 Gneiss-gray wacke, depositsof, character and origin 



of. 



Gneiss-pelite, deposits of, origin and character of. 894-904 



Gneiss psephite, origin and character of ._ 857-860 



Gneissic tuffs, discrimination between sedimen- 

 tary gneissic rocks and . 909,913 



Gold, association of , with argillite.. 1095,1096 



association of, with base metals 1169-1174 



deposition of, by ascending solutions 1089-1099 



forms of occurrence of 1169 



precipitation of - 1091-1099 



solubility of 1075,1089-1091,1171 



Gold-bearing quartz veins, origin of, by magmatic 



segregation, theory concerning.. 1048-104'.* 

 Gold deposits, formation of, possible modes of . . 1041-1042, 



1048-1049,1050 



Gold ore of Sierra Nevada, origin of .. . 1084 



Gold placer deposits, formation of _ 1040-1043 



Gogebic districts of Michigan, iron ore deposits of, 



as affected by topography 1219 



Gordon, H. A., on gold deposits of New Zealand 1042 



Grain, silica potash, soda, etc., in 454 



Grain of rocks, effect of, on rate of weathering .. 533-534 

 See also Recrystallization. 



Grains and grasses, disintegration of rocks by 445 



Granite, induration of, along joints 549 



injected, example of 647 



losses of constituents of, by weathering .. 507,522,523 



strain in, shown by quarrying. __ 598 



Grant, U. S., on action of organic matter in reduc- 

 ing and precipitating oxidized prod- 

 ucts.. --. 1157 



on agency of igneous intrusions in producing 



iron-silicite rocks 840 



on zonal arrangement of metamorphic minerals 



peripheral to irtrusive masses 719 



Granulation of minerals, energy factors involved 



in 770-771 



relation of recrystallization to 737, 748 



temperatures favorable to 740 



water content of rocks as affecting. 741-748 



Graphite, character, occurrence, and alterations of. 212 



chemical and physical constants of 197 



Grasses and grains, disintegrating effects of, on 



rocks 445 



Grass Valley, Cal., gold veins of, constant tenor of. 1137 



secondary enrichment of gold ores at. 1184-1185 



Page. 

 Gravel, pebble, and bowlder deposits, discussion 



of 853-S60 



Gravity, metamorphic effects of 46-50 



ground- water motions as affected by. . 146-147, 148-149 

 Gravity, specific. See Specific gravity. 

 Grays Peak, Colo., disintegration of rock at, by 



freezing and thawing 443 



Gray wacke, deposits of, character and origin of.. 880-883 



metamorphosed, character and origin of 883-886 



discrimination of 909-910 



photomicrographs of _ „. 888 



serpentinized, formation of _ 881-882 



Gray wacke-gneiss, deposits of, character and origin 

 of __ 



Gray wacke-schist, deposits of, character and origin 

 of. & 



Gray wacke -slate, deposits of, character and origin 

 of 



Great Basin, deposits in, reference to 559 



ground water of, rate of flow of. ._ 585 



streams and lakes of, soluble material trans- 

 ported and deposited in. 551-554 



Great Salt Lake, calcium chloride deposits of 542 



precipitation of salts in 552, 553 



Greenalite, character and occurrence of 284 



photomicrograph of 836 



Gris wold , L . S. , on whetstones of Arkansas 853 



Grits, deposits of, character and origin of 879-880 



Groddeck, A. von, on contact metamorphic origin 



of ores _ 1050 



Grossularite, alterations and alteration products 



of 302,303,305,307,373,384,398 



chemical and physical constants of... 197,299 



occurrence and associations of _ 301 



sources and modes of formation of. 301, 314, 370, 383, 406 

 Grossularite and melanite, alterations and altera- 

 tion products of 3S3, 38:4, 387, 398 



Grossularite, pyrope, and melanite, alterations and 



alteration products of . . 383, 384, 387, 390, 398 



Groth, P. H., on composition of zeolites 329 



Ground water, absence of, in ore-bearing districts, 



mistaken inferences from 1063-1065 



acids present in 93 



channels traversed by, size of .... 580-582,1201 



chemical and physical principles controlling ac- 

 tion of 65-123 



circulation of . 123-158, 416-429, 571-593, 661-668, 1021-1029 



causes of, summary of 152 



channels of, variations in size and continuity 



of 1201 



character and conditions of _ 129, 



137, 139-146, 572-579 



concentration of soluble material by 543-551 



conditions governing 129-158 



downward movements of, factors influ- 

 encing 417-419 



factors or forces influencing 146-156,416-417 



adhesion. 150-152 



friction 153-154 



gravity. 146-147,578 



gravity and heat 148-149 



heat _ 147-148 



limiting formations 576-578 



mechanical action _ 149 



molecular attraction _ 150-152 



openings in rocks 129-146 



temperature 157 



vegetation _. 152,422-423 



rate of 154-156,583-588 



