Hydrothermal anhydrite in veins is commonly hydrated to gypsum by groundwater in in the vicinity of-surface exposures. It is usually affiliated with the minerals halite and sulfur. Gypsum is the commonest sulfate mineral.[seventeen] Pure gypsum is white, but other substances observed as impurities may give an array of shades to https://www.propanraya.com/id/produk/eco-gypsum-ee-4050