Hydrothermal Anhydrite in veins is usually hydrated to gypsum by groundwater in close to-surface exposures. It is usually associated with the minerals halite and sulfur. Gypsum is the most common sulfate mineral.[17] Pure gypsum is white, but other substances found as impurities could give a wide range of hues to https://www.propanraya.com/id/produk/eco-gypsum-ee-4050