Home – Home – Jornals – Russian Geology and Geophysics 2018 number Неопубликованное

Kotulskite PdTe – the most abundant palladium mineral in platinum-group element (PGE) deposits of the Fedorova-Pana Layered Complex (FPC). This paper presents new data on the noble metal paragenesis and chemical composition of kotulskite from the North PGE Reef at the Peshempakhk target. At this target, the North Reef, extensively explored at the Kievey deposit, extends eastward. Low-sulfide mineralization containing up to 15 g/t PGE + Au outcrops here but does not form ore bodies at depth. The study aims to identify mineralogical distinctions between the discontinuous mineralization at Peshempakhk and the ore bodies of FPC deposits. 890 grains of platinum-group minerals and Au were studied in polished sections using electron microscopy, including energy-dispersive X-ray microanalysis; kotulskite was confirmed by Raman spectroscopy against a synthetic analogue. The noble metal assemblage at Peshempakhk comprises (in relative vol. %): kotulskite (38 %), isomertieite (22 %), sperrylite (18 %), stibiopalladinite (11 %), hollingworthite (3 %), and gold (3 %). The noble metal paragenesis of the target differs from that of the main FPC deposits, where sulfides and tellurides of PGE predominate, namely braggite, vysotskite, merenskyite, moncheite, and kotulskite. Kotulskite at Peshempakhk averages 8.4 wt. % Bi, whereas deposits exhibit a more complete kotulskite-sobolevskite solid solution series with average Bi concentrations between 13.3 and 20.2 wt. %. Additionally, the studied kotulskite includes an antimony variety containing up to 10.3 wt. % Sb. The simultaneous presence of the two kotulskite types points to an origin under the most low-temperature conditions of a magmatic setting. Thus, the noble metal paragenesis and composition of kotulskite from the FPC PGE mineralization are its key typomorphic features. These results can be used to forecast ore zones in similar settings.