SG Heritage Dictionary

Anhydrite [Noun] Webster's Dictionary 1828

A species of sulphate of lime, anhydrous gypsum, of which there are several varieties; compact, granular, fibrous, radiated, sparry, siliciferous or vulpinite, and convoluted.

Anhydrite [Noun] Webster's Dictionary 1913

A mineral of a white or a slightly bluish color, usually massive. It is anhydrous sulphate of lime, and differs from gypsum in not containing water (whence the name).