Brown crystals of the extremely rare mineral parwelite from the type and only known locality worldwide the Langban deposit (Långban, Filipstad, Värmland County, Sweden). Parwelite,Mn10Sb2As2Si2O24, is a mineral with strange composition since it is not clear if it is a antimoniate, an arsenate or a silicate, or all at the same time. — Photo: David Hospital · CC BY-SA 4.0
Parwelite
Parwelite is an IMA-recognized mineral species in the silicate class, with the chemical formula Mn²⁺₁₀Sb⁵⁺₂As⁵⁺₂Si₂O₂₄.
It crystallizes in the monoclinic crystal system (space group A2/a).
Key properties: Mohs hardness 5.5; specific gravity 4.62; Pale brownish orange streak; Subadamantine, oily luster; optically biaxial.
IMA symbol Pwe, IMA status: approved, named in 1966.
Found in a high-temperature skarn assemblage, in recrystallized manganoan carbonate ores.
It is found associated with Lº a ngbanite, spessartine, hausmannite, berzeliite, caryinite.
The name refers to Dr. Alexander Parwel, Swedish chemist, Swedish National History Museum, Stockholm, Sweden, who has performed many analyses of Lº angban minerals, including this one.