Understanding gold-(silver)-telluride-(selenide) mineral deposits

Abstract

Gold-(silver)-telluride (selenide) ores occur as epithermal orogenic and intrusion related deposits. Although Te and Se are chalcophile elements and share geochemical affinity with Au, formation of selenides and other elements Ag-Au require acidic or reducing enfironments. The thermodynamic stability conditions for Au and Ag-tellurides and native tellurium indicate an epithermal environment. Analysis of mineral paragenensis, textures and compositional variation in tellurides/selenides suggest petrogenetic processes involving interaction with fluids leading to Au scavenging and entrapment in tellurides, changes in chemistry/rates of fluid infiltration and attaining equilibrium in a given assemblage.