Locality: João Firmino claim, Linópolis, Divino das Laranjeiras, Doce valley, Minas Gerais, Brazil Field of View: 03 mm Orange Crystal Ushkovite and Brown Spheres Atencioite; Photo and Collection Fernando Brederodes. — Photo: Fernando Brederodes · CC0
Ushkovite
Ushkovite is an IMA-recognized mineral species in the phosphate class, with the chemical formula MgFe³⁺₂(PO₄)₂(OH)₂·8H₂O.
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Laueite structural group.
Key properties: Mohs hardness 3.5; specific gravity 2.38; Pale yellowish streak; Vitreous to pearly on cleavages, greasy on fractures luster; optically biaxial.
IMA symbol Ukv, IMA status: approved, named in 1982.
Found in granite pegmatites, as an alteration product of triplite formed by weathering.
It is found associated with Triplite, francolite, mitridatite, beraunite, Fe–Mn oxides (Ilmen Mountains, Russia).
The mineral was named to honor Sergei L’vovich Ushkov (1880–1951), Russian naturalist, student of the Il’men National Forest, Russia.