Anhydrite is a mineral composed of calcium sulfate. It is a naturally occurring mineral and is usually found as a white or grayish-white powder. It has a Mohs hardness of 3 and a specific gravity of 2.9. Anhydrite can be used in the production of cement, plaster, and other building materials, as well as for agricultural purposes such as fertilizer. It is also used in the production of sulfuric acid, which is an important industrial chemical.