Hydrothermal anhydrite in veins is commonly hydrated to gypsum by groundwater in in close proximity to-surface exposures. It is frequently associated with the minerals halite and sulfur. Gypsum is the most typical sulfate mineral.[seventeen] Pure gypsum is white, but other substances located as impurities could give an array of colours https://www.propanraya.com/id/produk/eco-gypsum-ee-4050