Article name About a New Find of Yutenbogaardtite in Transbaikalia
Authors Yurgenson G.A. Doctor of Geological-Mineralogical Sciences, Professor, Chief Researcher,
Bibliographic description Yurgenson G. A. About a new find of yutenbogaardtite in Transbaikalia // Transbaikal State University Journal. 2023. Vol. 29, no. 4. P. 44–53. DOI: 10.2109/2227-9245-2023-29-4-44-53.
Category Earth and Environmental Sciences
DOI 549.553.2
DOI 10.2109/2227-9245-2023-29-4-44-53
Article type Original article
Annotation The relevance lies in the need to have complete data on the mineralogy of the ores of large gold deposits. One of such deposits in Transbaikalia is Darasunskoye, the relatively new veins of which, discovered in 1985, were quickly worked out and poorly studied. One of these veins, the mineral composition of which is practically not studied, is the Geneva vein, which is rich in gold content, the complexity of the mineral composition, and the depth of formation. The purpose of the study is to determine the mineral forms of gold in a deep-seated gold-quartz-sulfide vein. The object of study is pilsenite-hessite-uytenbogaardtite-hessite-tsumoite-gold-sphalerite-chalcopyritepyrite mineral association. The subject of the study is the chemical composition and forms of yutenbogaardtite isolation. Method and methodology are as follows: optical and electron microscopy to determine the forms of segregations and variations in the chemical composition of minerals. Results: for the first time in a deep-lying (horizon 617 m from the surface) vein of the Geneva Darasun deposit of the gold-quartzsulfide formation, Au and Ag sulfide yutenbogaardtite was found in close association with chalcopyrite and low-grade native gold, mainly electrum, tellurides (tsumoite, hessite, volynskite, empressite , pilsenite), as well as pyrite, sphalerite, and galena. The vein minerals are represented by quartz, siderite, and muscovite. The chemical composition of uytenbogaardtite (wt. %): Ag 42.97 ‒ 53.57; Au 33.78 ‒ 44.62; S 11.28 ‒ 13.61; Cu 0.65 ‒ 1.14. Average content of elements: Ag 49.35; Au 37.74; S 12.43; Cu 0.664. The theoretical content should be Ag 58.46; Au 32.02; S 9.52. A feature of the chemical composition of uytenbogaardtite is its non-stoichiometric nature, which is expressed in a lack of silver, a part of gold, and an excess of sulfur. It is probably due to the peculiarities of the solution-melt composition, expressed in the inhomogeneity of the Au-Ag-S solid solution containing Cu, Te, Bi as impurities, displayed in close paragenesis with chalcopyrite and tellurides. Low grade Au, which is associated with yutenbogardtite, contains from 43.32 to 56.42 % Ag and is electrum by their ratio.
Key words yutenbogaardtite, chemical composition ,native gold, electrum, tellurides, sulfides, quartz, Zhenevskaya vein, Darasun deposit, Transbaikalia
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