Hydrothermal Anhydrite in veins is usually hydrated to gypsum by groundwater in around-area exposures. It is often affiliated with the minerals halite and sulfur. Gypsum is the most common sulfate mineral.[seventeen] Pure gypsum is white, but other substances found as impurities could give a variety of colours to local deposits. https://www.propanraya.com/id/produk/eco-gypsum-ee-4050