Manganlotharmeyerite
Manganlotharmeyerite is an IMA-recognized mineral species in the arsenate class, with the chemical formula CaMn³⁺₂(AsO₄)₂(OH)₂.
It crystallizes in the monoclinic crystal system (space group C2/m). It is a member of the Natrochalcite structural group.
Key properties: Mohs hardness 3; specific gravity 3.77; Light brown streak; Adamantine luster; optically biaxial.
IMA symbol Mlmy, IMA status: approved, named in 2001.
Found in discordant veinlets formed by late-stage remobilization of arsenic during retrograde metamorphism of a carbonate-hosted, syngenetic exhalative massive braunite deposit.
It is found associated with Calcite, tilasite, ailaufite.
The prefix, mangano, alludes to the Mn3+ dominance within the lotharmeyerite subgroup of the tsumcorite group.