Fluckite (Mine Giftgrube, Neuenberg, Sainte-Marie-aux-Mines, Haut-Rhin). Musée de minéralogie de Strasbourg — Photo: Ji-Elle · CC BY-SA 3.0
Fluckite
A triclinic calcium-manganese hydrogen arsenate hydrate.
Intro adapted from Wikipedia (CC BY-SA).
Fluckite is an IMA-recognized mineral species in the arsenate class, with the chemical formula CaMn²⁺(AsO₃OH)₂·2H₂O.
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Fluckite structural group.
Key properties: Mohs hardness 3.5–4; specific gravity 3.05; refractive index 1.629; optically biaxial.
IMA symbol Fck, IMA status: approved, named in 1978.
A post-mine low-temperature reaction product of carbonate gangue with arsenical solutions derived from arsenic (Gabe-Gottes mine, France).
It is found associated with Arsenic, tennantite, skutterudite, sainfeldite, pharmacolite, villyaellenite, picropharmacolite, calcite, dolomite, ankerite, quartz (Gabe-Gottes mine, France).
In honor of Pierre Fluck, mineralogist, Louis Pasteur University, Strasbourg, France, who found the first specimen.