Anhydrite mineral specimens found in Cumbria, the specimens are a pale grey or sometimes white colour with a crystaline nature, however, the mineral its self as a whole tends to be quite soft. Anhydrite is a soft, anhydrous form of calcium sulphate, considered an evaporite mineral that occurs in extensive layered deposits in sedimentary basins where large volumes of sea water have been evaporated, it is typically interbedded with halite (salt), gypsum and limestone in accumulations that can be up to hundreds of feet. Initially discovered in a salt mine near Hall in Tirol, Aistria in 1794. Depth is critical to anhydrites stability and formation, if it were to form or become exposed nearer the surface the mineral becomes hydrated with water and reverts to gypsum. It is at times used as a substitute mineral during the maufacture of plaster of Paris. These mineral specimens are available in various sizes and will come supplied in a white card tray with an information label.