260 
INDEX. 
Page. 
Chalcocite, occurrence and character of . 79 
Chalcopyrite, occurrence and character 
of - 86 
Climate of Silverton quadrangle 25-26 
Columbia mine (Cement Creek), descrip- 
tion of 25? 
Columbia mine (Savage Basin\ descrip- 
tion of 214 
Congress mine, descriptionof 238 
Copper, average annual price of 24 
■ m scurrence and character of 86 
Copper, gray. Sec Tetrahedrite. 
Copper, yellow. -See Chalcopyrite. 
Cosalite, analysis of . .. 220 
occurrence of -- 84 
Cotta, B. von, cited . . 43, 44, 67, 70, 103 
Country rock, metamorphism of, in con- 
nection with ore deposition. 114-131 
relation of Assures to .' 53-55 
relation of lode ores to 101 
Crooke, W., reference to 99 
Crosby, W.O., cited- 66 
Cross, W., cited 60 
outline of geology by 29-39 
photographs by 13,38,50 
reference to 13, 55, 63, 64, 115, 247 
Cross fractures of lodes 59 
Cunningham Gulch , description of 167 
lodes of 167-170 
ore from, plate showing structure of. 88 
Custer lode, description of 184 
Paubree, A., cited > 65 
reference to 52 
Davis and Gold King lodes, description 
of 254-255 
De Launay, cited 136 
Decomposition, superficial, products of . . 87 
Deer Park, lode ores of 94 
Deer Park Creek, faulting and Assuring 
at — 55 
Depth, effect of, on character of lode 
ores 98-100 
Dikes, relation of fissures to 55 
Displacement, Assuring and relations of. 55-56 
Dn es mine, description of 165-166 
ore from, plate showing structure of. 86 
Doelter, C, cited 134 
Dolly Varden lode, description of 190-191 
Dolomite, occurrence and character of.. 72 
E.G.S. vein, description of 155-156 
Early Bird mine, description of 189 
East Iowa vein, description of 158 
Emmons, S. F., acknowledgments to 14 
cited 66,106,132,136,139 
quoted 107, ?"• *S, 217 
reference to 79,81,106,227,232 
Emmons. S. F., and Tower, G. W., cited.. 44 
Empire group of mines, description of.. - 252 
Empire and Jennie Parker mines, descrip- 
tion of._ 252 
Enargite, occurrence and character of . . . 79 
Endlich.F.M., cited... 20,46,168 
reference to 35 
Engineer Mountain, andesitic rock from, 
mineralogical composition of. 122 
latite from, analysis of 122 
Page. 
Engineer Mountain district, country rock 
in, metamorphism of 119-124 
Enrichment, secondary, of ore bodies, 
discussion of ...*.. 136-141 
Evening Star claim, description of 184 
Fair vie w prospect, description of 253 
Faulting, Assuring and, relations of 55-56 
Faults, extent and age of - 37 
Fissures, age of 60 
Fissuring, faulting as an accompaniment 
of. « 55 
Fissures, intersections and relative age 
of 56-60 
origin of 63-67 
persistence of 61- 63 
relation of dikes to 55 
relation of country rock and rock 
structure to 53-55 
strike-fractures dipping with 59 
strike-fractures parallel with 59 
See also Fissures, ore-bearing; Lodes. 
Fissures, lode. -See Fissures, ore-bearing. 
Fissures, ore-bearing, coordination of 45-53 
course of , diagram showing 47 
distribution of 44-45 
See also Fissures. 
Flora vein, descriptionof 212 
Fluorite, occurrence and charactei of... 74-75 
Forest and Old Lout mines, description 
of 192-193 
Frank Hough mine, description of 189-190 
Fry, W.R., cited 242 
Galena, change to sphalerite. 100 
Galena, occurrence and character of 80-81 
Galena Mountain. Assures on _ 45 
Assures, intersections of 57 
course of 49 
lodes of 170-174 
Galena Queen mine, description of 240 
Galenobismuthite, occurrence of 84 
Gangue minerals of the ores _ 70-87 
Genesee -Vanderbilt mine, description 
of _ 227-230 
fourth level of , plan of 229 
ore bodies of, sketch plan showing 
changes in 230 
stock ore in, value of 113 
underground workings of. plan of 228 
George Washington lode, description of . 178 
Gold, occurrence and character of.. 85-86 
Gold King mine, description of 254-256 
Gold Nugget claim, description of 173 
Golden Fleece mine, Assures at, course of. 49 
Golden Fleece vein, description of 183 
Grabill,L.R., cited 107 
Grand Prize mine, description of 231 
Gray copper. See Tetrahedrite. 
Green Mountain, Assures at, intersec- 
tions of 57 
Green Mountain mine, description of .. 168-169 
Groddeck. A. von, cited . 44,70 
Ground water, discussion of 141 
Guitermanite. occurrence and character 
of 82 
Guston mine, description of 221-227 
longitudinal and transverse sections 
through 224 
