The San José-Itos mines, Oruro, Bolivia: structure and Ag-Sn mineralization

A new cartography of the veins and a detailed mineral sequence is provided for the Itos and San José mines, Oruro, Bolivia. The mineral sequence comprises an early stage with arsenopyrite, arsenian pyrite and cassiterite, followed by a stage with tin sulphosalts and Sn-rich sphalerite. In the latest stage, silver and lead sulphosalts formed along with galena, acanthite and sphalerite and minerals typical of advanced argillitic alteration (zunyite and minerals of the alunite supergroup). The occurrence of pseudocubic alunite with jamesonite and zunyite suggests that these minerals are not good indicators for a supergene vs. hydrothermal origin of the advanced argillitic hydrothermal alteration. Concentration of critical elements (In, Ge, Ga, Nb, Ta) in sphalerite, stannite and cassiterite is steadily low.Peer Reviewe