Se-bearing polybasite-Tac from the Martha mine, Macizo del Deseado, Santa Cruz, Argentina

MÁRQUEZ-ZAVALÍA, M.F.; BINDI, L.; MÁRQUEZ, M.; MENCHETTI, S

MINERALOGY AND PETROLOGY

Springer Wien

Lugar: Viena, Austria; Año: 2008 vol. 94 p. 145 - 150

0930-0708

Abstract Se-bearing polybasite-Tac is associated with galena, chalcopyrite, sphalerite, tetrahedrite, electrum and quartz at the Martha mine, an epithermal silver–gold deposit located adjacent to the Deseado Massif, Santa Cruz province, Argentina. Three samples, with variable chemical composition and showing the 111 unit-cell type, were studied by means of X-ray single crystal diffraction and electron microprobe. The unit-cell parameters were modeled using a multiple regression method as a function of the Ag, Sb, and Se contents. The predicted values resulted in excellent agreement with experimental unit-cell parameters. We observed that high contents of selenium in polybasite are associated with relatively low copper contents. This finding corroborates previous studies that the copper content of pearceite–polybasite group minerals can be very low if selenium is present.