| Haidingerite | |
| Formula: | Ca(AsO3OH)·H2O |
| Mohs: | 2 – 2.5 |
| Gravity: | 2.95 |
Haidingerite is a calcium arsenate mineral with formula Ca(AsO3OH)·H2O. It crystallizes in the orthorhombic crystal system as short prismatic to equantcrystals. It typically occurs as scaly, botryoidal or fibrous coatings.[1] 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.[2]
It was originally discovered in 1827 in Jáchymov, Czech Republic. It was named to honor Austrian mineralogist Wilhelm Karl Ritter von Haidinger (1795–1871).[3] It occurs as a dehydration product of pharmacolite in the Getchell Mine, Nevada.[1]