INDEX. 
Page. 
Andesite, methods of distinction in general. 13, 14 
Andesite, early, difficulty of distinguishing. 13 
distribution and characteristics of 12, 13 
eruption of 9 
Andesite, later, difficulty of distinguishing. 13 
distribution and characteristics of 13 
eruption of 10 
Ararat Hill, lava of 14 
Argentite, occurrence of 1G, 23 
Basalt, eruption of 10 
Belle of Tonopah shaft, rock in which lo- 
cated 14 
Big Tono shaft, rock in which located 15 
Boston Tonopah shaft, in later andesite 13 
Brougher,W., interests of, in original claims. 7 
Brougher Mountain, basin partly inclosed 
by 14 
reference to 10, 11, 26 
Butler, J. L., discovery of the Tonopah ores 
by 7 
Butler Mountain, altitude of 9 
basin partly inclosed by 14, 26 
Calcite, occurrence of 17 
California Tonopah mine, reference to 8, 19 
Chalcedony, occurrence of 17 
Chalcopyrite, occurrence of 16, 17, 23 
Climate of Tonopah, characteristics of 7 
Comstock district, comparison of veins of. . 28 
Copper, occurrence of, in veins formed sub- 
sequent to early andesite intrusion. 16 
possibility of larger proportion of, in 
depth 28 
Dacite, later intrusive, distribution and 
characteristics of 15 
Dacite eruptions and later intrusions 10, 11 
Dacite-breccia formation, distribution and 
characteristics of 15 
Dacites, distribution and characteristics of. 14, 15 
Discovery of the ores and development of 
the claims 7-9 
Erosion, recent 12 
Erosion interval between the two andesites. 15 
Fault planes, redeposition of metals along . 24, 25 
Faulting, economic interest in 12 
occurrence and character of 11 
Faults, principal ones shown on map PL I 
Fraction mine, early andesite rock in 13, 14 
Fraction No. 1 shaft, rock in which located . 15 
Fraction No. 2 shaft, rock in which located . 15 
Fraction No. 3 shaft, rock in which located. 15 
Page. 
Future possibilities in the district, geolog- 
ical evidence of 28 
G. & H. tunnel, in white rhyolite 14 
Galena, occurrence of 17 
Geological conditions, represented by ideal 
cross section of Tonopah rocks 26 
Geological formations, pre-Tertiary 9 
Geological formations and events in the 
district, sequence of 12 
Geological history of the distric t 9-12 
Geological principles, application of 25-28 
Gold, proportion of, to silver by weight in 
veins formed subsequent to early 
andesite intrusion 16 
proportion of, to silver in the ores 9 
Gold, free, occasional occurrence of 16 
Gold Hill, outcrop of early andesite on 12 
Gold Mountain, veins of rhyolitic period, 
characteristics and metallic con- 
tent 17 
Gold Mountain district, reference to 27 
Golden Anchor shaft, in later andesite 13 
Golden Mountain, reference to dacite con- 
tact on 15 
Granite of the region, intrusive in lime- 
stone 9 
Halifax shaft, in later andesite 13 
Heller Butte, character of rock composing. . 14 
King Tonopah shaft, rock in which located . 14 
Knox, C. E., information furnished by 8 
Lake sediments 10 
Lead, possibility of finding, in depth 28 
Leases in 1900 and 1901 7 
Limestone of the region 9 
Little Tonopah shaft, in later andesite 13 
MacNamara mine, early andesite rock in. . 13, 19 
Map showing veins outcropping at Tono- 
pah 19 
Map, geologic, of Tonopah district PL I 
Map, topographic, of the region, reference 
to 9 
Microscopic examination of primary ores. . 23 
Midway mine, early andesite rock in 13 
Mineralization at contacts of large dacite 
necks, character of 17 
periods and nature of 15-18 
subsequent to dacite intrusions 17 
subsequent to early andesite intrusion . . 15 
subsequent to early rhyolite intrusion . . 16 
subsequent to later rhyolite intrusion . . 16 
29 
