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 . Fig. 11 viously tetrahedrons with the single planes of the tetrahedronsreplaced by three triangular faces. Again take the Trigonal trisoctahedron (Fig. 19) and removethe alternate groups of faces, (observe these groups are the an-alogues of the single alternate face in the octahedron) and, fromthe respective development of the unshaded and shaded faces, there 12 A POPULAR GUIDE TO MINERALS. Fig. 19 Fig. 20 Fig. 21 arises Figs. 20 and 21
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 . Fig. 11 viously tetrahedrons with the single planes of the tetrahedronsreplaced by three triangular faces. Again take the Trigonal trisoctahedron (Fig. 19) and removethe alternate groups of faces, (observe these groups are the an-alogues of the single alternate face in the octahedron) and, fromthe respective development of the unshaded and shaded faces, there 12 A POPULAR GUIDE TO MINERALS. Fig. 19 Fig. 20 Fig. 21 arises Figs. 20 and 21, or a right and left deltoid dodecahedron, inwhich however, the previous triangular faces become four-sidedfaces.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmineral, bookyear1912
