Palladium tellurides and bismuthtellurides in sulfide copper-nickel ores of the Savabeisky ore occurrence (Nenets Autonomous District, Russsia)

Abstract

Research subject. The Savabeisky sulfide copper-nickel ore occurrence, located in the central part of the Khengur (Central Pay-Khoy) gabbro-dolerite complex of the Pay-Khoy, within the Yugorsky Peninsula, located in the Far North-East of the European part of Russia, in the Arkhangelsk region, between the Barents and Kara Seas.Materials and methods. Samples of copper-nickel ores with noble metal mineralization were studied. Palladium tellurides and bismuthtellurides were characterized using optical and scanning electron microscopy, electron backscatter diffraction (EBSD), X-ray structural analysis and Raman spectroscopy.Results. Bismuthtellurides in the Paykhoysko-Vaigach-Yuzhnonovozemelskiy region – michenerite, merenskyite and unidentified palladium telluride of the kotulskite–merenskyite series with crystal formula Pd2(TeSbBi)3 – were found for the first time. The unit cell parameter of Pay-Khoy michenerite was calculated using X-ray diffraction analysis data: a = 6.638(2) Å. According to Raman spectroscopy, the palladium tellurides and bismuthtellurides of the Savabeisky ore occurrence were distinguished into 4 groups: Sb-kotulskite (does not contain Raman-active modes), unnamed PGM Pd2(TeSbBi)3 (bands in the range 95–103, 121–126 cm–1, obtained for the first time), Sb-merenskyite (band 126–135 cm–1), michenerite (bands with maxima 100 and 116 cm–1, obtained for the first time). The Kikuchi lines for michenerite and the mineral of the kotulskite–merenskyite series were obtained by the EBSD method.Conclusions. The diagnosis of palladium tellurides and bismuthtellurides is a rather complicated problem (wide variations in compositions, low hardness, small size, thin intergrowths of several individuals, the presence of impurities, etc.) affecting the determination of their mineral form and requiring an integrated approach. The Raman spectra of michenerite and unnamed PGM can be used as standards for the rapid identification of their natural forms, in contrast to EBSD, which requires improved sample preparation. The relatively high content of antimony in the ore minerals and noble metals minerals at the Savabeisky ore occurrence is the antimony metallogenic specificity characteristic of the entire Uralsko-Novozemelskiy province.