Transactions . he ciystals of chromite affordstrong evidence that they are of early crystallization, perhaps antedatingmost of the particles of silicates by which they are inclosed. The smallparticles of silicates, now^ serpentine, inclosed in the larger grains ofchromite show that the crystallization of silicates began early andapparently continued after the chromite was completed. A large partof both chromite and silicates may have crystallized contemporaneously. ** Graphic method suggested by X. L. Bowen. Loc. cit. 128 RECENT STUDIES OF DOMESTIC CHKOMITE DEPOSITS The grains of disseminated
Transactions . he ciystals of chromite affordstrong evidence that they are of early crystallization, perhaps antedatingmost of the particles of silicates by which they are inclosed. The smallparticles of silicates, now^ serpentine, inclosed in the larger grains ofchromite show that the crystallization of silicates began early andapparently continued after the chromite was completed. A large partof both chromite and silicates may have crystallized contemporaneously. ** Graphic method suggested by X. L. Bowen. Loc. cit. 128 RECENT STUDIES OF DOMESTIC CHKOMITE DEPOSITS The grains of disseminated chrome ore in Fig. 20 are largely euhedraP^and enclosed in olivine which is partly altered to serpentine; the greaterportion of the chromite crystallized before the olivine. The smallirregular particles of original silicates (now serpentine) included in chromitemay have crystallized slowly, while the chromite proceeded more rapidlyto completion, which was followed by the crystallization of most of ?pjQ_ jg_ I HI\ SECTION OF CHROME ORE FKOM CaSTLE CrAGS MINE, DuNSMUlR, Calif. Anhedral chromite indented and included by pyroxene which in-cludes ALSO small crystals OF EUHEDRAL CHROMITE. X 15. About 6 mi. southwest of Yreka, toward Fort Jones, there is aremarkable chrome *^ The thickly set grains of lustrous blackchromite form about 60 per cent, of the rock, and the interspaces arefilled with brilliant green chrome diopside tinged here and there by a pink ^ This general relation of the silicates and euhedral chromite, shown in Fig. 20,is well illustrated by others. See Vogt, Zeit. prak. geol. (1894) 2, 389; R. Beck:The Nature of Ore Deposits, translated by W. H. Weed, 29, 1905; N. Wyssotzky:Die Platinseifen gebirge, von Iss und Nischny, Tagil im Ural, 1913, plate VIII,No. 3 and 4, plate IX, No. 3, plate X, No. 1. In Fig. IX he shows euhedral chromiteincluding anhedral platinum and itself included in groundmass of anhedral platinum. ^^ Sample was given me by J
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
