The ore deposits of Utah . usually formedbut is of relatively slight importance. The oxidation of a secondary sulphide zonethat has been so enriched that it consists largelyof copper sulpliides results in the formation ofnative copper, cuprite, and melaconite or tenor-ite, and very commonly of silicates and car-bonates. Such an alteration seems to haveproduced the rich oxidized ores of the CopperMountain mine in the Lucin district (see PLXXIII), though sulphides were not observedm the mine at the time of the writers absorption of copper by amorphous sili-ceous and aluminous material
The ore deposits of Utah . usually formedbut is of relatively slight importance. The oxidation of a secondary sulphide zonethat has been so enriched that it consists largelyof copper sulpliides results in the formation ofnative copper, cuprite, and melaconite or tenor-ite, and very commonly of silicates and car-bonates. Such an alteration seems to haveproduced the rich oxidized ores of the CopperMountain mine in the Lucin district (see PLXXIII), though sulphides were not observedm the mine at the time of the writers absorption of copper by amorphous sili-ceous and aluminous material has formed oreranging from rather high grade to that con-taining but httle copper. In the deposits containing abundant arsenic,as the Tintic mines and the Gold Hill mine ofthe Chfton district, a series of copper-arsenicoxidation minerals form an important part ofthe ore. LEAD-SILVER DEPOSITS. The primary ore of deposits in which leadand silver are the most important metallic con-stituents is composed chiefly of pyrite and. Figure 33.—Diagram .showing the relation of galena and its oxidationproducts. Drawn from specimen from Alta Consolidated mine,Little Cottonwood district. Central area, galena; dark band sur-rounding galena and penetrating it along cleavages, anglesite withsome cerusite; outer band, basic ferric sulphate, possibly beaverite. galena with variable amounts of sphalerite,tetrahedrite, enargite, chalcopyrite, and otherminerals. In most deposits the mineral com-bination in which the silver is present has notbeen determined. It is closely associated withthe sulphides and aUied minerals and probablyoccurs as silver sulphide and combined witharsenic and antimony, intergrown with lead,zinc, and copper minerals. When acted on by oxidizing solutions, thegalena first alters to the sulphate, anglesite in the presence of calcium andmagnesium carbonates changes to the lead car-bonate, cerusite, or combines with ferric sulphateto form plumbojarosite or other co
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectminesandmineralresou
