Hydrothermal Anhydrite in veins is often hydrated to gypsum by groundwater in in close proximity to-surface area exposures. It is usually related to the minerals halite and sulfur. Gypsum is the commonest sulfate mineral.[17] Pure gypsum is white, but other substances located as impurities might give a variety of colors https://www.propanraya.com/id/produk/eco-gypsum-ee-4050