Peculiarities of the chemical composition of spinel group minerals in the Talnakh copper-nickel ore deposit (North-West of the Siberian platform)

Aplonov V. S., Zolotarev A. A.

Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2017. V. 146. N 3. P. 51-69

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Language: Russian

Abstract

There are generalized data of the representative collection of chemical analyses of spinel group minerals from various rocks of the Talnakh deposit (in total — 240 microprobe analyses). Data on composition of spinelids from rocks of Zubovskoe (4 analyses) and Norilsk-1 (53 analyses) deposits have been used also. Spinel group minerals in igneous rocks and the metamorphic halo of the Talnakh deposit belong to five mineral species: magnetite, chromite, magnesiochromite, spinel and hercynite. Magnesioferrite, maghemite and titanomaghemite may be present in the ore field rocks also: some chemical analyses in the studied collection might be recalculated in chemical formulas of these mineral species. Ulvöspinel was identified in rocks of Norilsk-I and Zubovskoe deposits. Despite the diversity of spinel group minerals, variations of their compositions are described by only three schemes of isomorphism: Mg ↔ Fe²⁺; Al ↔ Fe³⁺ ↔ Cr; Fe^3+VI + Fe^3+IV ↔ Ti^4+VI + Fe^2+IV. The role of other elements — Si, Ni, Co, Mn, Ca, Na, K, Zn, V — is insignificant.

Key words: Talnakh deposit, chemical composition, spinel group.