Arapovite
Arapovite is an IMA-recognized mineral species in the silicate class, with the chemical formula (K₁₋ₓ ₓ)(Ca,Na)₂U⁴⁺Si₈O₂₀ [x ≈ 0.5].
It crystallizes in the tetragonal crystal system (space group P4/mcc). It is a member of the Steacyite structural group.
Key properties: Mohs hardness 5.5–6; specific gravity 3.43; Vitreous and pitchy luster; optically uniaxial.
IMA symbol Apv, IMA status: approved, named in 2003.
Occurs as dark green zones in turkestanite crystals in a glacial cobble in moraine rich in alkaline rock fragments.
It is found associated with Microcline, aegirine, polylithionite, stillwellite-(Ce), turkestanite.
The mineral was named to honor Yu. A. Arapov (1907-1988), geologist and author of many works on the geochemistry, mineralogy and petrology of Middle Asia.