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.
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(n.)
A mineral consisting of the arseniate of lime; -- so named in honor of W. Haidinger, of Vienna.
  

General Information:
 Chemical Formula:
Ca(AsO3OH)·(H2O)
 Composition:
(Molecular Weight = 181.01 gm)
Calcium 22.14 % Ca
Arsenic 41.39 % As
Hydrogen 1.11 % H 
Oxygen 35.36 % O 
 Empirical Formula:
CaAsO3·(H2O)
Physical Properties:
 Cleavage:
[010] Perfect
 Color:
colorless or white.
 Density:
2.95
 Diaphaniety:
Transparent to Translucent
 Hardness:
2-2.5 - Gypsum-Finger Nail
 Luster:
Vitreous - Adamantine
 Streak:
white
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