PINS Bree 
Acid original rocks, 91-126, 144-151. 
———, Age of, 12, 13. 
——-—, Absence of copper in, 426. 
——~—, Chronological relation of, to basic eruptives, 32, 432~ 
436. 
——-—, Classification of, 91. 
——-, Distribution of, 155. 
——~—, Frequency of, 91. 
——-—, Huronian and Keweenawan compared, 405. 
——~—, Kinds of, 112-125. 
———-—, augite-syenite, &c., 112-124. 
———~— felsite and quartz-porphyry, 95-112. 
———-—, granite, 125. 
———~—, quartzless porphyry, 91-95. 
———, Summary of, 126. 
——~—, Views on origin of, 12, 150. 
Agate Bay, Amygdaloids of, 137, 287-289. 
——, Olivine-diabase of 72, 76, 287. 
——, Section at, 288, 289. 
Agate Bay Group, 284-294. 
——— at Agate Bay, 72, 288-290. 
——-—, Amygdaloids of, 136, 286-289. 
——_—, Anorthite-rock of, 292. 
——~—, Bedding of, 288. 
———, Copper possibly present in, 429. 
——_-, Dikes of, 293, 294. 
——— at Encampment Bluff, 47, 285. 
——— at Encampment River, 284, 285, 291. 
——~—, Faults in, 290, 291. 
——— on French River, 284. 
——— on Gooseberry River, 286, 293. 
——— near Lester River, 292. 
——~—, Olivine-diabase of, 76, 286. 
—— —, Relation of acid and basic rocks of, 435. 
———, Sandstone of, 292, 293. 
—— — on Split-Rock River, 291. 
———on Talmage River, 286. 
——-—, Thickness of beds of, 290. 
———, Thinning of, at eastern end of Minn. coast, 294, 298. 
——-—, Warping of beds of, 290. 
Agate Harbor, Trends and dips near, 178, 413. 
Agogebic Lake, Eastern Sandstone at, 360. 
—-—, Lower Division at, 158. 
Albany and Boston mine, Augite-syenite pebbles of, 115, 118, | 
119, 190, 191. 
——-—, Conglomerate of, 190, 191. 
——-—, Dip of strata at, 187. 
———, Quartzless-porphyry of, 94, 191. 
Albite in olivine-diabase, 70. 
Algoma mine, Ferruginous sandstone of, 374. 
Allouez mine, Dip at, 187. 
Alteration of augite to chlorite, 43, 64, 79. 
——— diallage, 52. 
——— ferrite, 79, 98, 102, 114, 125, 
——— green substance, 71, 89. 
——— hornblende, 56, 114, 125. 
——— magnetite, 41. 
——— uralite, 52. 
—, epidote-quartz of amygdaloid, 199. 
— of feldspars to chlorite, 64, 89. 
——— through prehnite to chlorite, 64. 
——— to prehnite, 89. 
— — glass-base in quartz-porphyry, 101. 
—— ——ferruginons prehnite, 89. * 
——— in olivine.diabase, 70. 
—— olivine to biotite, viridite, and tale, 39. 
----— greenish substance, 38. 
——— magnetite (?), 39. 
—— orthoclase to chlorite, 51. 
— — plagioclase to chlorite, 51. 
———-— green substance, 71. 
———— prehnite, 46. 
——prehnite to chlorite, 89 
———— chlorite, calcite, and green earth, 89. 
———— epidote and calcite, 89. 
———— orthoclase, 89. 
—, Pseud-amygdaloidal, 63, 64. 
— of uralite to chlorite, 52. 
Aminicon River, Orthoclase gabbro of, 52, 54. 
——, Rocks of, 255, 256. 
Amygdaloids, 87-91, 134-139. 
—, Absence in Huronian, 403, 445. 
—, Alteration of, 89, 90, 199. 
—, Amygdules of, 135, 136. 
—of ashbed-diabases, 183. 
—, Characteristics of, 135, 136. 
—, Constituents of, 88, 89. 
——, Ferrite of, 88. 
——, Plagioclase of, 88. 
—, Copper, deposition in, 90, 421, 422. 
—, Distribution of, 155. 
—, Fluidal structure in, 83. 
—, Matrix of, 87, 88. 
| —, Pumpelly on, 89-91. 
—, Relations of, to diabase-porphyrites, 87, 89. 
—, Stratiform, 137. 
Amygdules of amygdaloids, 89, 90. 
—, Elongation of, 136. 
Analcite of amygdaloids, 90. 
Animikie Group, 367-386. 
—-—, Bell on “crowning overflow " of, 381, 382. 
—.—, Contact of, with Keweenaw series, 157, 297, 405. 
(447) 
