Formula: CaSO₄

Species: Sulfates

Colour: Colourless, bluish, blue-grey, violet, burgundy-red, white, rose-pink, brownish, reddish, grey, dark grey; colourless in transmitted light

Lustre: Vitreous, Greasy, Pearly

Hardness: 3 – 3½

Specific Gravity: 2.98

Crystal System: Orthorhombic. Isostructural with Ferruccite; isostructural and isomorphous with α-BaSO4 and α-SrSO4.

Name: Named in 1804 by Abraham Gottlob Werner from the Greek άνυδρος (“anhydros”) meaning “without water”, in allusion to the lack of water in its composition, in contrast to gypsum, which contains water.

Type Locality: Salt mine, Hall valley, Hall, Innsbruck-Land District, Tyrol – Austria