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