SN-GE-CD-CU-FE-BEARING SULFIDES AND SULFOSALTS FROM THE BARQUILLA DEPOSIT, SALAMANCA, SPAIN

Sn-Ge-Cd-Cu-Fe mineralization is observed in the Fuentes Villanas mine , which exploits the hydrothermal vein deposit of Barquilla, Salamanca , Spain. Two associations are present, one consisting of cassiterite, cernyite, greenockite, tetrahedrite, herzenbergite and minor chalcopyr ite, Ag-Pb-Bi-bearing sulfosalts, galena and native bismuth, in the ve ins; the other involves chalcopyrite, stannite, stannoidite, mawsonite , tetrahedrite, cadmian briartite, bornite, mohite, native bismuth, bi smuthinite and digenite in the altered host-rock close to the veins. T he first one crystallized before an intense episode of sericitic alter ation, whereas the second is contemporaneous with it The crystallizati on sequence of Sn-bearing minerals proposed is: cassiterite --> herzen bergite --> cernyite --> stannoidite --> mawsonite. Available experime ntal data suggest that these minerals crystallized in a sequence contr olled by the increase of S fugacity or decrease of temperature (or bot h). The germanium content of cadmian briartite probably was picked up from the host rocks by migrating fluids.