Transactions . of chromiteis like that of a dike intruded along the middle portion of the much largerdike of pyroxenite. Near this dike-shaped body of chrome ore are othersmaller masses of chromite in parallel position. Westgate points out J. S. DILLEU 143 tliat, although the great dike is mainly pyroxciiite, the middle portioncontaining the chroniite is rich in olivine, and the rock thus becomesperidotite or dunite. The chrome belt in the Bonanza, claim has athickness of about 90 ft. (27 m.), and its structure is broadly thickest band of chromite is 13 in. (33 cm.) and it lies near
Transactions . of chromiteis like that of a dike intruded along the middle portion of the much largerdike of pyroxenite. Near this dike-shaped body of chrome ore are othersmaller masses of chromite in parallel position. Westgate points out J. S. DILLEU 143 tliat, although the great dike is mainly pyroxciiite, the middle portioncontaining the chroniite is rich in olivine, and the rock thus becomesperidotite or dunite. The chrome belt in the Bonanza, claim has athickness of about 90 ft. (27 m.), and its structure is broadly thickest band of chromite is 13 in. (33 cm.) and it lies near themiddle of the belt. Three properties were in active development during part of ore was mined (600 tons reported), but as the distance toNorthern Pacific Railroad shipping points is about 35 mi. (56 km.), andthe transportation facilities are not quite completed, there were no ship- Timber. Fig. 26.—Chrome belt of Boulder River and Rock Creek, Montana. (L. G. Westgate.) ments. In the Benbow mine the chromite occurs in a nearly verticaldeposit from Z}^ ft. to 5^^ ft. ( to m.) in width. In places it isfrozen to the wall rock, which may contain subordinate layers of chromiteparallel to the main deposit. The depth of the ore deposit is not defi-nitely known, but the exposures on the canyon walls suggests a dei)th ofat least 700 ft. (213 m.) In length the deposit in the Benbow claimappears to be more or less continuous for 8000 ft. ( km.), and the ton-nage to a depth of 100 ft. is estimated at 250,000 tons. The ore is black, granular chromite. Where the grains have notgrown in contact with each other they are often octahedral, and it ispossible to get specimens that are spotted with small but quite perfectcrystals. According to Westgate, whose description of these depositsis being published by the U. S. Geological Survey, besides that in theorebodies, chromite occ
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
