Whiteite-(MnMnMg)
Whiteite-(MnMnMg) is an IMA-recognized mineral species in the phosphate class, with the chemical formula Mn²⁺Mn²⁺Mg₂Al₂(PO₄)₄(OH)₂·8H₂O.
It crystallizes in the monoclinic crystal system (space group P2/a). It is a member of the Jahnsite structural group.
Key properties: Mohs hardness 4; specific gravity 2.61; Pale orange streak; Vitreous luster; optically biaxial.
IMA symbol Wt-MnMnMg, IMA status: approved, named in 2015.
From a Mn-rich, carbonate-rich zone, in a deeply weathered, Precambrian sedimentary iron ore deposit (Monarch quarry), likely as a late-stage, low-temperature hydrothermal phase.
It is found associated with Hematite, hausmannite, baryte, Mn-rich calcite, rhodochrosite.
Root name, whiteite, indicates a member of the group with M(3) = Al3+; the suffix indicates sequentially the dominant atom in the X, M(1), and M(2) structural positions.