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. Ulvospinel 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 ↔ Fe ²⁺ ; Al ↔ Fe ³⁺ ↔ 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.