Hydrothermal Anhydrite in veins is often hydrated to gypsum by groundwater in close to-surface exposures. It is commonly linked to the minerals halite and sulfur. Gypsum is the most typical sulfate mineral.[17] Pure gypsum is white, but other substances identified as impurities could give an array of shades to nearby https://www.propanraya.com/id/produk/eco-gypsum-ee-4050