Mesaite
A very rare hydrated calcium-manganese divanadate related to fianelite.
Intro adapted from Wikipedia (CC BY-SA).
Mesaite is an IMA-recognized mineral species in the vanadate class, with the chemical formula CaMn²⁺₅(V₂O₇)₃·12H₂O.
It crystallizes in the monoclinic crystal system (space group P2/n).
Key properties: Mohs hardness 2; specific gravity 2.74; Light pinkish orange streak; Vitreous luster; optically biaxial.
IMA symbol Msa, IMA status: approved, named in 2015.
Formed on asphaltum blocks in a mine tunnel in sandstone by the oxidation in a moist environment of montroseite-corvusite assemblages in a roll-front U-V-deposit.
It is found associated with Ansermetite, kegginite, martyite, morrisonite, rossite/metarossite, sherwoodite.
The name refers to the county in Colorado in which the Packrat mine is located.