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