Elements of mineralogy, crystallography and blowpipe analysis from a practical standpoint .. . acture of copperas has been superseded by a process of gal-vanizing iron in which copperas is a by-product. MARCASITE—White Iron Pyrites. Composition.—FeSj, as in pyrite. General Description.—Ferric sulphide is dimorphous. Mar-casite differs from pyrite in crystalline form, and in little occurs in orthorhombic forms, and in crystalline masses. Thecompound crystals have given rise to such names as cockscombpyrites, spear pyrites, etc., from their resemblance to these , with radiat
Elements of mineralogy, crystallography and blowpipe analysis from a practical standpoint .. . acture of copperas has been superseded by a process of gal-vanizing iron in which copperas is a by-product. MARCASITE—White Iron Pyrites. Composition.—FeSj, as in pyrite. General Description.—Ferric sulphide is dimorphous. Mar-casite differs from pyrite in crystalline form, and in little occurs in orthorhombic forms, and in crystalline masses. Thecompound crystals have given rise to such names as cockscombpyrites, spear pyrites, etc., from their resemblance to these , with radiated structure. Color on fresh fracture is usuallywhiter than in pyrite. Crystallization.—Orthorhombic, d?c^ : i : usually tabular parallel to base. Simple forms show unit prism m, basal pinacoid c and often one 200 DESCRIPTIVE MINERALOGY. or more brachy domes as g= cad?\c. Compound five-lings with twin plane in, Fig. 391, are are mm = 105° 5, eg = 157° 39. Fig 387. Fig. 388 Fig. 389. Littnitz, Bohemia. Folkstone, Eng. Fig. 390. FiG. Physical Characters. H., 6 to Sp. gr., to , metallic. Opaque. Streak, nearly black. Tenacity, brittle. Color, pale brass-yellow, darker after , imperfect prismatic (angle of 105° 5). Before Blowpipe, Etc.—As for pyrite. Similar Species.—As for pyrite, from which it is only distin-guishable by crystalline form, cleavage, and, to a slight degree, bylighter color. Remarks.—Marcasite is more readily decomposed than pyrite, and is, therefore, aneven less desirable constituent in building material, etc. It is found at Cummington,Mass.; Warwick, N. Y.; Joplin, Mo.; Haverhill, N. H.; and in many other localitiesand is usually mistaken for pyrite. Uses, are the same as for pyrite. ARSENOPYRITE.—Mispickel. Composition.—FeAsS. (Fe , As , S per cent.)sometimes with replacement of iron by cobalt, or arsenic by anti-mony in part. General Description.
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