MINERALOGY OF OXIDIZED ORES AT THE IK-DAVLYAT GOLD-BASE-METAL DEPOSIT, THE SOUTHERN URALS

Abstract

Three types of oxidized ores are identified in the Ik-Davlyat gold-base-metal deposit in the southern Urals: (1) carbonate-sericite-chlorite mineralized rock, (2) vein-shaped quartz-goethite-illite clay, and (3) limonitized rock related to veins. Heavy concentrate of the first type of ore is composed of goethite, rutile, native gold Au0.91Ag0.08Cu0.01, and chalcophanite Zn1.02Mn2.98O4 · 3H2O. The second type of ore contains goethite, rutile, Pb-bearing jarosite, native gold Au0.90−0.93Ag0.06−0.08Cu0−0.01Fe0−0.01, silver amalgamide (schachnerite) Ag0.75Hg0.97Au0.98-Ag0.75Hg0.97Au0.28, coronadite (Pb1.72Mn7.51Fe0.41Cu0.36)8O16, a chalcophanite-hydrohetaerolite mixture, and cerussite. Gold of the highest fineness (Au0.98Ag0.01Cu0.01) is associated with silver amalgamide. The third type of ore is quite similar to the first variety but contains a jarosite impurity. The composition of oxidized ores indicates a difference in composition of primary ores, in particular, the presence of lead minerals in primary veins. The first finding of chalcophanite in Russia is confirmed by chemical, optical, and X-ray data.