Crystal Chemistry of “Malakhovite,” an Anthropogenic Analog of Khesinite from Burnt Dumps of the Chelyabinsk Coal Basin (South Urals)

Single crystals of “malakhovite” (an anthropogenic silico-oxide from burnt dumps of the Chelyabinsk coal basin; sp. gr. P $$\bar {1}$$ , a = 10.555(4) A, b = 10.928(3) A, c = 9.059(3) A, α = 106.338(12)°, β = 95.87(7)°, γ = 124.40(2)°, V = 781.0(5) A3, Z = 1, R1 = 0.0378 have been investigated by electron-probe microanalysis, Raman spectroscopy, and X-ray diffraction analysis. The idealized formula of the mineral is Ca4(Fe $$_{{8.56}}^{{3 + }}$$ Mg1.72Ca0.82Fe $$_{{0.55}}^{{2 + }}$$ Mn0.22Ti0.13)Σ12.00(Fe $$_{{6.48}}^{{3 + }}$$ Al2.82Si2.71)Σ12.01O40. It is shown that malakhovite is not only chemical but also crystal chemical anthropogenic analogue of khesinite (Ca4Mg2Fe $$_{{10}}^{{3 + }}$$ O4Fe $$_{{10}}^{{3 + }}$$ Si2O36). The relationships between the malakhovite and the minerals from the dorrite–khesinite series of the rhonite group in the sapphirine supergroup are discussed.