Platinoids in the Kaalamo differentiated massif, Northern Priladozhye (Karelia, Russia)
Lavrov О. В., Kuleshevich L. V.
Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2016. V. 145. N 2. P. 58-74
The Kaalamo massif is located in the Northern Priladozhye, in Karelia, at the extension of the Kotalahti ultrabasic nickeliferous intrusion belt from Finland. The 1.89 Ga massif is differentiated from pyroxenites to diorites. Nickel-copper-sulfide mineralization with platinoids is connected with the pyroxenite phase. Ores are represented by two mineral types: pentlandite-chalcopyrite-pyrrhotite and chalcopyrite, both enriched in PGE. Pd and Pt bismuthotellurides and tellurobismuthites of palladium and platinum are represented by kotulskite, sobolevskite, merenskyite, michnerite, moncheite, keithconnite, telluropalladinite; while Pt and Pd sulfides — by vysotskite, cuperite, braggite, palladium pentlandite and more rare phases. The highest-palladium minerals occur in pentlandite-chalcopyrite-pyrrhotite ores. Native gold, intergrowing with kotulskite, contains commonly microinclusions of Pd stannides (1—3 mkm) — paolovite and atokite. Ores with 20—60 % copper sulfides (Cu 0.2—6 %) contain 5.1—6.6 ppm PGE and up to 0.13—2.3 ppm Au. There are also common, in these ores, Pd minerals, observed arsenides and sulphoarsenides of Pt, Rh, Ir, Os and Ru, silver gold and paolovite. These Pt, Rh, Ir, Os and Ru arsenides and sulphoarsenides are represented by sperrylite, ruthenium platarsite, hollingworthite and irarsite. All these minerals have been revealed in the massif for the first time. In total, the paper displays data on compositions of about 25 PGE minerals in Kaalamo ores.
Key words: platinum-group minerals, Kaalamo differentiated massif, Northern Priladozhye, Karelia.