VERY SMALL (about 0,5 mm) brown single crystal aggregate of the extremely rare mineral manganarsite from the type locality in Langban (Långban, Filipstad, Värmland County, Sweden) and only one of the three known localities worldwide. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Manganarsite
Manganarsite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Mn²⁺₃As³⁺₂O₄(OH)₄.
It crystallizes in the hexagonal crystal system.
Key properties: Mohs hardness 3; specific gravity 3.64; Pale pink streak; Vitreous luster; optically biaxial.
IMA symbol Mna, IMA status: approved, named in 1985.
Coating armangite, and filling fractures, in a museum specimen from a metamorphosed Fe–Mn deposit.
It is found associated with Calcite, barite, hematite, fluorite, armangite.
The name refers to MANGANese and ARSenic in the composition.