INDEX. 



A. 



Page. 



Adularia, alteration of earlier andesite to 207-209 



analysis of 87 



character of 86-N7, 228 



formation of, chemistry of 230-231 



occurrence of 22, 229-230 



explanation of 212-218 



origin of 22,228,231 



sericite and, relations of 227-228 



view of 208 



Aguilera, J. G., on Mexican ores 269-270 | 



Albite, occurrence of, explanation of 212-213 



Allen, E. T., analysis by 252 ] 



Alteration. See Rock alteration. 



Ancylus? sp., occurrence of 67 



Andesite, earlier, alterations of 22, 31-32, 207-238 



alterations of, diagrams showing 218, 234, 218 



analyses of 57, 64, 65, 216 



character of 21,31-32,63,164-165,253 



classes of 32 



later andesite and, comparison of 35 



occurrence of 21, 32, 101, 164-165, 186-187 



specimens of, description of 213-216 



veins in 22, 83-% 



age of 83 



circulation channels in 831 



cross walls in 85 



mineralization of 85 



minerals ^^ 90 



view^I 208 



mines ancrwospects in, description of 115-191 



ores of ...." 86-90 



origin of 84-85 



oxidation of 90-94 



Andesite, later, alteration of 23, 238-252, 254 



alteration of, figures showing 242. 243 



period of 250-252 



analyses of 57, 66 



character of 21,33-34,253 



diagrams showing 242 



earlier andesite and, comparison of 35 



occurrence of 21, 34-35, 101, 179 



origin of 22 



shafts in ; 205-206 



study of 245-248 



veins in 261 



Ararat Mountain, erosion on 113 



rocks in 30,36,49,55,101,191-192,253-254 



veins in 22,101-104 



location of, map showing 102 



Argentite, occurrence of 22,92,94-95 



Arid lands, erosion in 111-112 



16843 No. 4205 19 



Page. 



Bagg, R. M., jr., fossils determined by 69 



Barium, alteration of 233-234 



Basalt, age of 56 



analysis of 57.64,65 



character of 21, 56, 63 



occurrence of 45, 55 



origin of 21-22 



Becker, G. F.. on mineralizing waters 237 



on propylite 236 



on sideritc 249 



on the Comstock lode 259,265 



Belle of Tonopah shaft, location of 198 



rocks and veins in 198-199 



water in 106 



Belmont Company, property of 125 



Belmont shaft, depth of 106, 19S 



lava from, analysis of 57, 60, 64 



location of 193 



rocks in 30,61.193-194 



section near, figure showing 193 



Big Tono shaft, data concerning 200 



depth of 106 



Biotite, alteration of 207,232 



Bischof , Gustav, on feldspar alteration 212-213, 233 



Blende, character of 88 



occurrence of 22 



Bonney, T. G., on volcanoes 260 



Booker & Bradford, map prepared by 26 



Borneo, rocks of 284 



Boston Tonopah shaft, depth of 106, 192 



location of 192 



rocks in 101,192 



Brauns, D., on mnscovite 281 



Brogger, W. C., diagram by 242 



Brougher, W., mention of 26 



Brougher dacite, analysis of 60, 65 



areas of, diagram showing 50 



character of 44-48,62-63 



contacts of, shafts at 200 



faulting due to 47 



hornblendes in 62 



occurrence of 44 



origin of 46-47 



Siebert tuffs and, relations of, figure showing 53 



Brougher Mountain, character of 44 



erosion on 113 



faulting near : 75, 146 



history of 67 



lava of, analysis of 57, 58, 60, 65 



origin of .' 146 



rocks of 36,46,49-51,55,60-61 



289 



