Atelestite Field of view: 1 mm Locality: Schmiedestollen, Wittichen, Schenkenzell, Rottweil, Region Freiburg, Baden-Württemberg, Germany — Photo: Henk Smeets – tomeikminerals.com · CC BY 4.0
Atelestite
A bismuth arsenate first found in Saxony's Erzgebirge district.
Intro adapted from Wikipedia (CC BY-SA).
Atelestite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Bi₂O(AsO₄)(OH).
It crystallizes in the monoclinic crystal system (space group P2_1/c). It is a member of the Atelestite structural group.
Key properties: Mohs hardness 4.5–5; specific gravity 7.14; Resinous to adamantine luster; optically biaxial.
IMA symbol Ale, grandfathered status — known before the IMA’s founding, named in 1832.
A rare secondary mineral found in the oxidized zone of bismuth- and arsenic-bearing mineral deposits.
It is found associated with Bismutite, eulytite, erythrite, bismutostibiconite, beyerite, preisingerite, walpurgite, mixite, conichalcite, torbernite, quartz.
Derivation not explicitly stated. Probably from the Greek for incomplete, as the composition was undetermined when the mineral was first described.