Abstract:

The bismuth minerals in the skarntype copper ore of the Jiama copper polymetallic deposit in Mozhugongka County, Tibet, has reached 0.23%, and can be used as an associated useful metal element. Based on the geochemical analyses, bismuth is closely correlated to the skarn and copper mineralization. The bismuth content is relatively higher in the skarn copper ore than those in other ores. In the vertical section, bismuth has concentrated in the same zone as copper of the vertical mineralization zoning. Analyzed by electron probe, bismuth mainly occurs in the bismuth minerals and bismuth-bearing sulfides, including wittichenite, tetradymite, aikinite, and bismuth-bearing tetrahedrite and bornite. The wittichenite is the major bismuth mineral in the Jiama deposit. It occurs as two occurrences, foliated/xenomorphic granular and dropwise in bornite, chalcocite and tetrahedrite. According to the occurrences and electron probe data, the wittichenite may form in two epochs at short time interval with normal chemical component and lower Bi, higher Cu and S, respectively. Therefore, bismuth in Jiama deposit should be comprehensively utilized, and it is also a significant clue for prospecting of copper mineralization.

Key words: bismuth minerals, wittichenite, Jiama copper polymetallic deposit