ИСТИНА

The content of Ni in the Norilsk sulfide ores is usually 2-5 wt. %, Co – 0.1-0.2 %, Ag – 2-100 g/t. Ni, Co, Ag are equally compatible with Mss and Iss. The main Ni and Co mineral-concentrator and carrier is pentlandite; Ag – hessite, electrum, kustelite. Thе trap formation was undergone low-grade metamorphism of submersion, wherein primary sulfides including pentlandite and other Ni-Co-Ag minerals begun to be replaced by a series of other minerals. Under high f S2 millerite-chalcopyrite-pyrite associations were formed during metamorphism (replacement) of exocontact primary ores with an abundance or with a predominance of pyrrhotite. Millerite NiS contains up to 9 wt. % Fe, 1,5% Co and forms full or partial pseudomorphs after large crystals of pentlandite and thin lamellae of pentlandite disintegration in chalcopyrite matrix. Thioshpinels – polydymite NiNi2S4, violarite FeNi2S4, siegenite CoNi2S4 developed in this association. They usually replaced pentlandite of primary ores along joints. Ag is part of the mineral series chalcopyrite CuFeS2 – lenaite AgFeS2. Pentlandite is replaced by sulfides in which Ni and Co predominates over S during metamorphism under conditions of sulfide sulfur deficient (log a S2 -12 – -15) and at high oxidation potential. Chalcopyrite and cubanite are replaced by bornite, then bornite are replaced by chalcosine. Godlevskite Ni9S8 closely associates with bornite, chalcosite, millerite and forms needle-shaped crystals and pseudomorphs after large pentlandite crystals. Heazlewoodite Ni3S2 is the most poor of S nickel sulphide. It is also the product of pentlandite and/or millerite substitution. It developed among chalcosine Cu2S, which is poor of S copper sulfide. Parkerite Ni3Bi2S2 forms metasomatic ingrowths in primary galena; rims of replacement around intergrowths of Pd and Pt bismuthides, hessite, and borders on native Bi. Bismutohauchecornite Ni9Bi2S8 and Shandite Ni3Pb2S2 form small flattened extended xenomorphic segregations in the area of eutectic aggregates Iss-PbSss in bornite. Argentopentlandite AgFe5Ni3S8 and Cupropentlandite CuFe5Ni3S8 form amoeba-shaped metasomes and less small crystals in association with chalcopyrite (without disintegration structures), chlorites, magnetite. Ni-Co-Fe arsenides, antimonides and sulphoarsenides are formed in the calcite and anhydrite metamorphogenoushydrothermal veins under low f S2. These pisolites involve up to 10-15 zones, formed by different Ni and Co minerals. They are orcelite Ni5As2, maucherite Ni11As8, minerals of nickeline NiAs – breithauptite NiSb series, split aggregates of rammelsbergite NiAs2 – löllingite FeAs2 series, rarer intermediate member of the rammelsbergite – safflorite CoAs2 series, sulfurous krutovite NiAs2 crystals, triarsenides – nickelskutterudite NiAs3, skutterudite CoAs3 and ferroskutterudite, rarer sulfoarsenides – minerals of gersdorffite NiAsS – 61 cobaltite CoAsS series, sulfoantimonides – ullmannite NiSbS. Ni arsenides predominate in the pisolites, S, Co, Fe content in them is insignificant. Therefore these elements are periodically accumulated in solutions and thin zones of Ni, Fe, Co sulphoarsenides. Ag minerals in the metamorphogenous-hydrothermal veins are acantite Ag2S, naumanite Ag2Se, stromeyerite AgCuS.