. The ore deposits of Utah. fissuring for 1^ to 2 a mile northwest of the BigIndian mine a shaft has been sunk to a depthof perhaps 100 feet; some good ore was on thedump, and shallow openings along the ledgeshow copper carbonates. Mineralized rockcan be found for at least half a mile south-east of the Big Indian mine, but not in suffi-cient quantity to have encouraged extensiveprospecting. At the surface and in the shallow workingsthe copper minerals are those that have re-sulted from oxidation processes, mainly azuriteand malachite and some cuprite. They aredisseminated t
. The ore deposits of Utah. fissuring for 1^ to 2 a mile northwest of the BigIndian mine a shaft has been sunk to a depthof perhaps 100 feet; some good ore was on thedump, and shallow openings along the ledgeshow copper carbonates. Mineralized rockcan be found for at least half a mile south-east of the Big Indian mine, but not in suffi-cient quantity to have encouraged extensiveprospecting. At the surface and in the shallow workingsthe copper minerals are those that have re-sulted from oxidation processes, mainly azuriteand malachite and some cuprite. They aredisseminated through the sandstone or occur(the carbonates particularly) as botryoidalmasses lining fissures or cavities. On the dumpspecimens containing sulphides were found,indicating that the oxidized ores were probablyderived from sulphides. Specimens of the impregnated sandstone sul-phide ore are seen under themicroscope to consistof sand grains cemented by sulphide. Many sand U. S. GEOLOGICAL SURVEY- PROFESSIONAL PAPER 111 PLATE L. A. PHOTOMICROGHAPH OF SAMDSTONE COPPER OKK. Lifrht areas,quartz grains; dark ;oi)i)er siilphiilos (€lialco<!ilcand chalcopyrile).
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectminesandmineralresou
