Sainfeldite Picture width: 1.5 mm Locality: Bauhaus, Richelsdorf Mountains, Hesse, Germany — Photo: Christian Rewitzer · CC BY-SA 3.0
Sainfeldite
Sainfeldite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Ca₅(AsO₄)₂(AsO₃OH)₂·4H₂O.
It crystallizes in the monoclinic crystal system (space group C2/c). It is a member of the Hureaulite structural group.
Key properties: specific gravity 3.04; optically biaxial.
IMA symbol Sai, IMA status: approved, named in 1963.
A post-mine low-temperature reaction product of carbonate gangue with arsenical solutions derived from arsenic (Sainte-Marie-aux-Mines, France).
It is found associated with Picropharmacolite, pharmacolite, ferrarisite, rauenthalite, fluckite, phaunouxite, calcite, löllingite (Sainte-Marie-aux-Mines, France); irhtemite (Bou Azzer.
The mineral was named to honor Paul Sainfeld (1916–), Honorary Curator, National School of Mines, Paris, France, who collected the type material.