Hydrothermal anhydrite in veins is usually hydrated to gypsum by groundwater in near-surface area exposures. It is frequently linked to the minerals halite and sulfur. Gypsum is the commonest sulfate mineral.[seventeen] Pure gypsum is white, but other substances observed as impurities might give a wide range of shades to regional https://www.propanraya.com/id/produk/eco-gypsum-ee-4050