1254 



INDEX. 



Page. 



Coal, carbon in, amount of 966 



carbon dioxide produced by combustion of, 



amount of.. l 464,972-973 



Coal beds, formation of _ 472 



Coarse-gi*ained rocks, rate of weathering of, as 

 compared with that of fine-grained 



rocks _ 533-534 



Cohesion, influence of, in ground-water circula- 

 tion 150-152 



Colloidal silica, silicification by 540,547 



Colorado, Aspen district of, silver -lead deposits of. 1084 

 San Juan district of. See San Juan district. 



Comey, A.M., on solubility of the sulphates 1075,1108 



Comminution, effect of, on amount of soluble ma- 

 terial in soils 495 



Complementary reactions, examples of 204,206 



Composition, chemical, importance of, in metamor- 

 phism 359 



Comstock lode, history of exploitation of 1224 



precipitation of metals at, hypothesis concerning 1083 



water in 1132 



width of, variations in 1224 



Concentration, second, conditions favoring 1177-1179 



See also Second concentration; Secondary en- 

 richment. 

 Concentration of soluble material by groundwater, 



discussion of 543-551 



Concretionary chert, photomicrograph of 836 



Condensation with recrystallization and mineral 



changes, features of 102-103 



Conductivity of rocks as regards heat, degree of... 53 



Consolidation of rocks, methods of 595-597 



Contact metamorphism, direct contact effect of.. 489-490 



exomorphic and endomorphic effects of 488 



extent of, conditions governing 649-652 



features of _.. 648 



indirect contact, effect of _ 490-494 



Conglomerate, original structure in, preservation 



of, after weathering.. 526 



Conglomerates, origin and character of... 855-857 



Conglomerates and pseudo-conglomerates, discrimi- 

 nation between, criteria for 910 



Conglomerate-schist, origin and character of 857-860 



Conn, H. W., on nitrogen compounds, decomposi- 

 tion of __ 465 



on nitrogen in soils, loss of, by manufacture of 



explosive powders 466 



' Copper, solution and precipitation of 1101-1104 



Copper and iron compounds, association of 1158-1163 



Copper ores, formation of... 1062,1158-1166 



of Lake Superior region, features of 1204-1205 



origin of __ 1136 



of Oregon, types of __ 1055-1056 



secondary enrichment of 1184 



Copper Queen mine, Arizona, secondary enrichment 



at. 1184 



Coquand, Henri, cited on bauxite deposits.. 9S5 



Coral limestones, dolomitization of. 799-800 



Corals, magnesium content of 798 



Cordierite, alterations and alteration products of. . 291, 



373,386,402 



chemical and physical constants of _ 198,291 



occurrence of — 291 



Cornwall, Pa., iron ore deposits at 1198 



Corundophilite, alterations and alteration products 



of. 347-348 



chemical and physical constants of 196,345 



Corundophilite, occurrence of 346-347 



sources and mode of formation of 318,347 



Corundum, alterations and alteration products 



of 223-225,373,380,381,402,408 



chemical formula of, physical constants of, and 



other data concerning 196,223 



occurrence of 223 



sources and mode of formation of 232, 



235-236, 318 , 328, 367 , 370, 381 , 383, 400, 624 

 Corundum and magnesite, alterations and altera- 

 tion products of 381, 4(H) 



Corundum and quartz, alterations and alteration 



products of 381,406 



Corundum, quartz, and calcite, alterations and al- 

 teration products of. 381,408 



Corundum, quartz, and potassium carbonate, alter- 

 ations and alteration products of.. 381,408 



Corundum-syenite, deposits of 1045 



Cotta, B. von, on contact metamorphic origin of 



ores 1050 



Covellite, zone of deposition of 1160 



Cramer, Prank, on strain in rocks. 98,598 



Credner, H., on origin of pegmatites 722 



Cripple Creek mining district, Colorado, fracturing 



in, complex character of 1225 



gold ores of 1172-1174 



ore deposits at, origin of 1085 



ore shoots near, intersecting fractures in 122" 



oxidation in, depth of 1181 



replacement of igneous rocks by ores in 1205 



Crosby, W. P., and Crosby, W. O., on cause of water 



power of sea mills of Cephalonia 149 



Crosby, W. O., on induration of Pikes Peak granite 



along joints 549 



on red color of soils, cause of- 482 



Crosby, "W. O., and Fuller, M. L., on origin of peg- 

 matites 722,723 



Cross, "Whitman, on flnviate origin of psephites of 



Cordilleras _ _ 854 



Cross, "Whitman, Iddings, J. P., Pirsson, L. V., and 

 Washington, H. S., on mineral com- 

 position of amphibole-gabbro 632 



Crustification, examples of 1146 



Crystalline rocks, average chemical composition 



of _ 890 



Crystalline and igneous rocks, analyses of 934-935 



Crystalline form, symmetry of, influence of, on sta- 

 bility of minerals... _. 360-361 



Crystallization, alteration of rocks by 203 



effect of pressure on 103 



effect of temperature on 78 



importance of, in metamorphism . _ 76 



methods of. r 74-76 



Culver, G. E., and Hobbs, "W. H., on decomposition 



of olivine-diabase in South Dakota . . 560 

 Cummingtonite, alterations and alteration prod- 

 ucts of. 285,287,373,381,404 



chemical and physical constants of 196,283 



occurrence of . _ _ 284 



Cupric salts, reactions involving 1161,1162,1163,1164 



Cupric sulphate, production of chalcocite from, 



equation showing reaction for 1111 



reactions involving .._ 1161,1162 



reversible reaction of, with ferrous sulphate... 1102 



Cuprite, production of, equation showing. 1158 



Cuprous chloride, precipitation of gold by, equation 



showing .' 192,1082 



