Hydrothermal anhydrite in veins is often hydrated to gypsum by groundwater in around-surface exposures. It is often affiliated with the minerals halite and sulfur. Gypsum is the most typical sulfate mineral.[17] Pure gypsum is white, but other substances uncovered as impurities may give an array of shades to neighborhood deposits. https://www.propanraya.com/id/produk/eco-gypsum-ee-4050