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Native sulfur deposits on fumarolic fields at Ebeko volcano (Northern Kuriles, Russia) are enriched in chalcophile elements (As-Sb-Se-Te-Hg-Cu) and contain rare heavy metal sulfides (Ag2S, HgS, and CuS), native metal alloys (Au2Pd), and some other low-solubility minerals (CaWO4, BaSO4). Sulfur incrustations are impregnated with numerous particles of fresh and altered andesite groundmass and phenocrysts (pyroxene, magnetite) as well as secondary minerals, such as opal, alunite, and abundant octahedral pyrite crystals. The comparison of elemental abundances in sulfur and unaltered rocks (andesite) demonstrated that rock-forming elements (Ca, K, Fe, Mn, and Ti) and other lithophile and chalcophile elements are mainly transported by fumarolic gas as aerosol particles, whereas semimetals (As, Sb, Se, and Te), halogens (Br and I), and Hg are likely transported as volatile species, even at temperatures slightly above 100°C. The presence of rare sulfides (Ag2S, CuS, and HgS) together with abundant FeS2 in low-temperature fumarolic environments can be explained by the hydrochloric leaching of rock particles followed by the precipitation of low-solubility sulfides induced by the reaction of acid solutions with H2S at ambient temperatures. The elemental composition of native sulfur can be used to qualitatively estimate elemental abundances in low-temperature fumarolic gases.

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This article provides data on the identification and distribution of Au-Ag minerals in the tailing dump of the processed ores in the pyrite-polymetallic deposit within the Salair ore field (Talmovskiye Sands, Salair). The mineral and chemical compositions of the samples were studied using atomic absorption, mass spectrometry with inductively coupled plasma, X-ray diffractometry, and scanning electron microscopy. We have established that a horizon of secondary enrichment was formed (with Au and Ag contents up to 5,3 and 53.7 g/t, respectively) over a long period of the tailing dump existence (more than 90 years) and at a depth of 0,6-0,8 meters. Gold and silver are unevenly distributed along the section and are present in three species:1) native (Aus, Ags), 2) mineral (acantite, petrovskaite), and 3) isomorphic (sulfides and secondary films). The identified residual and newly formed gold-silver minerals indicate active supergene processes of Au-Ag dissolution, migration, and precipitation. The transformation of native particles occurs through both chemogenic and mechanical processes.