Haidingerite

Haidingerite is a calcium arsenate mineral with formula Ca(AsO₃OH)·H₂O. It crystallizes in the orthorhombic crystal system as short prismatic to equant crystals. It typically occurs as scaly, botryoidal or fibrous coatings. It is soft, Mohs hardness of 2 to 2.5, and has a specific gravity of 2.95. It has refractive indices of nα = 1.590, nβ = 1.602 and nγ = 1.638. It was originally discovered in 1827 in Jáchymov, Czech Republic. It occurs as a dehydration product of pharmacolite in the Getchell mine, Nevada.

References

• Palache, C., H. Berman, and C. Frondel (1951) Dana’s system of mineralogy, (7th edition), v. II, pp.708–709.
• Mindat with location data
• Webmineral data
• Mineral Data Publishing - PDF