CD-TETRAHEDRITE, FIRST FIND IN THE USSR

Abstract

Essentially cadmium tetrahedrite (freibergite) was identified [in the Ushkatyn-III deposit of Atasu type in central Kazakhstan], where barite-galena ore bodies replace cryptogranular limestone. Fahlore minerals in this deposit range in composition from low-antimony tennantite to tetrahedrite and have Sb/(Sb + As) ratios of 3 to 97; tetrahedrite is more extensively developed. Cadmium enriches tetrahedrite highest in antimony, in the parts of the ore body farthest from the feeder fault. The temperature of formation of the equilibrium galena-barite association, as calculated from the sulfur-isotope distribution, ranges from 280° to 140° C. Cadmium-bearing tetrahedrite and freibergite form intergrowths up to 0.15 mm in size in galena and barite and at galena-barite contacts. The composition of the mineral was studied with the electron microprobe at 25 kV. These and other study results are discussed.