卷 9, 编号 1 (2023)

Primary and supergene Te minerals are identified in quartz veins of the Priozernoe deposit (Sverdlovsk oblast, Northern Urals, Russia) and studied by optical methods, electron microprobe analysis, X-ray diffraction and Raman spectroscopy. Tellurides include altaite, hessite, melonite, petzite, and sylvanite. Their individual grains and intergrowths occur as small inclusions in quartz. Supergene minerals include telluroperite, northstarite, adanite, burckhardtite, kuranakhite, and schieffelinite. They replace galena, hessite and cerussite or form monomineral grains and veinlets in quartz. Northstarite, adanite, and schieffelinite are found for the first time in Russian Federation, while the findings of telluroperite and burckhardtite are second. Kuranakhite is found for the first time in the Northern Urals. The findings of supergene Te minerals in Russia are reviewed.

The paper presents the results of a mineralogical study of sulfide ores of the Samolazovskoe deposit (Aldan Shield) and the products of their experimental bacterial oxidation in a heap. Pyrite and marcasite are the major minerals of primary ores. They form fine-grained crystalline and micrometer-grained to cryptocrystalline aggregates. Sphalerite, galena, chalcopyrite, pyrrhotite, fahlore, luzonite, bournonite and other Sb sulfosalts, stibnite and arsenopyrite are minor minerals. Tiemannite, coloradoite, calaverite, hessite, petzite and native gold are rare. The ores in the experimental biooxidation heap are mostly altered in its upper part. The secondary alteration products of ores include fine-grained Mg- and S-bearing calcite, smectites after feldspars, and films of Fe³⁺oxyhydroxides on the surface and in fractures of ore. In the lower part of the heap, technogenic processes are weak and are mainly related to the formation of gypsum. The sulfides are preserved throughout the heap vertical profile including very fine crystalline, colloform and botryoidal aggregates with a nonstoichiometric cation/anion ratio and the presence of As, Ni and Cu. The botryoidal aggregates of Fe disulfides contain galena, which forms a «microseptary» structure, which was not found in primary ores. The high-fineness native gold was found in assemblage with coloradoite and calaverite as inclusions in fine-grained aggregates of Fe disulfides. It is concluded on an insufficient impact of the bioleaching of refractory ores in an applied irrigation regime and the formation of secondary minerals that prevent the extraction of gold.

Mineralogical and thermobarogeochemical studies allowed us to reveal the crystallization conditions of plagioclase in volcanic complexes of Sulawesi Island (Pacific Ocean). The composition of plagioclase indicates the presence of three types of melts, which were involved in the formation of plagioclase phenocrysts in basalts, andesites and dacites, as well as crystallites in the groundmass of andesites and dacites. The analysis of glasses of heated melt inclusions in plagioclase indicates the involvement of two contrasting melts (mafic and felsic) in crystallization of phenocrysts. At the final stages of the volcanic process, plagioclase in matrix of andesites and dacites formed from another felsic melts with maximum alkali content. The presence of primary syngenetic melt and fluid inclusions in plagioclase phenocrysts indicates the phase separation of felsic magmas, which led to the crystallization of feldspar phenocrysts of different composition during the formation of dacites. Computational modeling in a program of (Putirka, 2008) based on the composition of plagioclases, glasses of heated inclusions and glasses from the groundmass allowed us to estimate the crystallization temperatures of feldspar phenocrysts in basalt (1160–1120 ºС), andesite (930–890 ºС) and dacite (1035–970 ºС), as well as the feldspar microcrystals in the groundmass of andesite (875–810 ºС) and dacite (900–865 ºС).