A popular guide to minerals : with chapters on the Bement Collection of minerals in the American Museum of Natural History, and the development of mineralogy . sses. The visitor to a representative collection, after the specimens ofgold and silver, will be most attracted by the beautiful crystalliza-tions of Copper. These specimens generally come from the re-markable deposits of native copper in the Lake Superior region ofnorthern Michigan. They exhibit the characteristic crystalliza-tions of the mineral (isome-tric system), the entrainedsprigs and branches of crys-tals, twins and massiveplate
A popular guide to minerals : with chapters on the Bement Collection of minerals in the American Museum of Natural History, and the development of mineralogy . sses. The visitor to a representative collection, after the specimens ofgold and silver, will be most attracted by the beautiful crystalliza-tions of Copper. These specimens generally come from the re-markable deposits of native copper in the Lake Superior region ofnorthern Michigan. They exhibit the characteristic crystalliza-tions of the mineral (isome-tric system), the entrainedsprigs and branches of crys-tals, twins and massiveplates, the common tetrahexa-hedrons (Figs. 305-309) cubesand superimposed octahedrons(Figs. 303-316), and amongstthem examples of the asso-ciated copper and silver al-luded to above. The copper deposits ofthe Keweenaw Point, Port-age Lake, and OntonagonRiver districts in north Michigan, are located in a regionwhich combines two contrasted series of rocks; conglomer-ates, sandstones, as a series originating in water, as a shore de-posit ; and igneous intruded rocks which have welled up from someinternal source of melted or fused mineral matter and penetrated. tig. 303 Fig. 304 GUIDE TO COLLECTIONS 113
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmineral, bookyear1912
