Hydrothermal anhydrite in veins is usually hydrated to gypsum by groundwater in near-area exposures. It is often related to the minerals halite and sulfur. Gypsum is the most typical sulfate mineral.[seventeen] Pure gypsum is white, but other substances uncovered as impurities may give an array of shades to local deposits. https://www.propanraya.com/id/produk/eco-gypsum-ee-4050