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 . sed with right and left tetra-hedrons. A distinction, pointed out by Prof. Miers, is that of thesix tetrahedron edges only four are truncated, and this is suffi- I30 A POPULAR GUIDE TO MINERALS cient to show that the truncating faces belong to a square prism andnot to a cube. Pyrite, the bisulphide of iron, is one of the most widely dis-tributed of the metaUic compounds. It is found in almost allclasses of rocks and is a common ingredie
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 . sed with right and left tetra-hedrons. A distinction, pointed out by Prof. Miers, is that of thesix tetrahedron edges only four are truncated, and this is suffi- I30 A POPULAR GUIDE TO MINERALS cient to show that the truncating faces belong to a square prism andnot to a cube. Pyrite, the bisulphide of iron, is one of the most widely dis-tributed of the metaUic compounds. It is found in almost allclasses of rocks and is a common ingredient of mineral veins. Itscrystallizations are well marked and often of much beauty, whileits brilliant luster and golden color have given it a fictitious re-semblance to gold, and frequently lead to its erroneous identifica-tion with that metal. Gold is indeed a common associate withpyrite, disseminated through it in almost invisible grains or dust,and the successful separation of gold from this gangue is to-day ametallurgical problem. The common crystalline forms of pyrite are the cube and thehemi-tetrahexahedron (pentagonal dodecahedron) (Figs. 338 and. Fig. 338 Fig- 339 Fig. 340 Fig. 341
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmineral, bookyear1912
