Joosteite
Joosteite is an IMA-recognized mineral species in the phosphate class, with the chemical formula Mn²⁺Mn³⁺O(PO₄).
It crystallizes in the monoclinic crystal system (space group I2/a). It is a member of the Wagnerite structural group.
Key properties: Mohs hardness 4; specific gravity 4.13; Metallic. Low to moderate bireflectivity; distinct anisotropy. R1-R2: n.d luster.
IMA symbol Joo, IMA status: approved, named in 2005.
From the alteration of oxidized sicklerite in a granitic rare-element pegmatite.
It is found associated with Lithiophilite, sicklerite, eosphorite, amblygonite, varulite, dickinsonite, hureaulite, apatite, unidentified Fe/Mn oxides.
The mineral was named to honor Mrs. Charlotte Jooste (1920-2009), Karibib, Namibia, for her support of pegmatite research in Central Namibia.