Mustard Gold in the Evevpenta Epithermal Gold–Silver Ore Occurrence (Kamchatka)

The paper describes the occurrence of so-called “mustard gold,” which forms discrete grains and replacement rims on calaverite (AuTe2) in the adularia-quartz veins of the Evevpenta epithermal ore occurrence in Kamchatka, Russia. Four varieties of mustard gold were identified: (1) pure mustard gold, (2) mustard gold containing areas and veinlets of homogeneous native gold, (3) mustard gold with relicts of Ag(-Au) sulfides, and (4) mustard gold intergrown with oxygen-containing compounds of Fe and Mn. It is hypothesized that the mustard gold at Evevpenta formed through hypogenic replacement of calaverite (AuTe2) during late hydrothermal stages. We propose that the chemical composition of mustard gold may serve as an indicator for the gold–antimony orogenic and gold-telluride epithermal deposits.