Hydrothermal Anhydrite in veins is often hydrated to gypsum by groundwater in in close proximity to-area exposures. It is commonly associated with the minerals halite and sulfur. Gypsum is the commonest sulfate mineral.[17] Pure gypsum is white, but other substances found as impurities may perhaps give an array of shades https://www.propanraya.com/id/produk/eco-gypsum-ee-4050