Identification: The mineral anhydrite is an anhydrous calcium sulfate (CaSO4). It is closely related to the mineral gypsum but has a marble-like texture and usually shows no crystal form. Anhydrite has a white, gray, or brown color and a white streak and is distinguished from calcite by its superior hardness of 3.0 to 3.5. The specific gravity is 2.89 to 2.98.

Occurrence: Anhydrite occurs deep in the subsurface of the State and is a common mineral seen in well cores.