anhydrite

[In Ger. anhydrit; Gr. avυ· δρος ( anudros ) = without water; referring to the fact that it contains no water of crystallisation.] Min.: A mineral cla ed by Dana under his Celestite group. Its crystals are orthorhombic. The hardne is 3-35; the sp. gr. 2.8992-955; the lustre vitreous, or somewhat pearly; the colour white, or brick-red. Composition: Sulphuric acid, 55-80 to 5978; lime, 40-21 to 43:06, with smaller portions of silica, sesquioxide of iron, and water. It is altered, by the absorption of moisture, into gypsum. It is divided by Dana into Var. 1. Ordinary. (a) Crystallised; (6) Fibrous; (c) Fine granular; (d) Scaly granular, under which is ranked Vulpinite (q.v.). Var. 2. Pseudomorphous. It occurs in various parts of the Continent, and in North America.