Ferrarisite
Ferrarisite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Ca₅(AsO₃OH)₂(AsO₄)₂·9H₂O.
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Lindackerite structural group.
Key properties: specific gravity 2.63; optically biaxial.
IMA symbol Fer, IMA status: approved, named in 1979.
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, sainfeldite, rauenthalite, phaunouxite, calcite, löllingite (Sainte-Marie-aux-Mines, France).
The mineral was named to honor Professor Giovanni Ferraris (1937–), Institute of Mineralogy, Crystallography and Geochemistry, University of Turin, Turin, Italy.