Anhydrite

Anhydrite, a mineral, consisting of anhydrous sulphate of lime, with some slight addition of sea-salt, appears in several varieties, as (1) granular, found in concretions with a foliated structure; (2) fibrous, easily broken with a fracture in delicate parallel fibres; (3) radiated, translucent; (4) sparry, or cube spar; (5) compact, of various shades, white, blue, gray, red. Anhydrite is converted into gypsum by combination with a certain proportion of water, and, where it is found in large masses, as on the south of the Harz Mountains near Osterode, the surface consists of gypsum. For building, anhydrite has no great value, on account of its tendency to this change; but some of its varieties, especially the Siliciferous or Vulpinite, found at Vulpino, in Upper Italy, are used for sculptures, and take a fine polish. When burned and reduced to powder, it is used as a manure, resembling gypsum in its effects.