Gold in the Oxidized Ores of the Olympiada Deposit (Eastern Siberia, Russia)

Abstract

Native gold and its satellite minerals were studied throughout the 300 m section of oxidized ores of the Olympiada deposit (Eastern Siberia, Russia). Three zones are identified in the studied section: Upper Zone ~60 g/t Au; Middle Zone ~3 g/t Au; Lower Zone ~20 g/t Au. Supergene and hypogene native gold have been found in these zones. Supergene gold crystals (~1 μm), their aggregates and their globules (100 nm to 1 μm) predominate in the Upper and less in Middle Zone. Relic hypogene gold particles (flattened, fracture and irregular morphology) are sporadically distributed throughout the section. Spongiform gold occurs in the Lower Zone at the boundary with the bedrock, as well as in the bedrock. This gold formed in the process of oxidation of aurostibite, leaching of impurities and its further dissolution. Hypogene gold is commonly isolated but for supergene gold typically associated with ferric (hydr)oxides. New formation of gold occurred due to oxidation of sulfide ores and release of “invisible” gold, as well as dissolution, mobilization and re-deposition of metallic hypogene gold. A model for the formation of oxidized ores with the participation of meteoric and low-temperature hydrothermal waters has been proposed.

Editorial for Special Issue “Mineralogy of Noble Metals and ‘Invisible’ Speciations of These Elements in Natural Systems, Volume II”

“…A number of articles [3][4][5][6][7][8][9][10][11] are devoted to the study of gold mineralization at different deposits and the characterization of the physicochemical conditions of its formation.…”

“…Silyanov et al [10] studied the oxidized ores from the Olympiada deposit (Eastern Siberia, Russia). They obtained new data on the morphology and chemical composition of native gold and proposed a model of supergene redistribution of noble metals and other elements in the oxidation zone.…”