Hydrothermal anhydrite in veins is often hydrated to gypsum by groundwater in in close proximity to-surface exposures. It is frequently connected to the minerals halite and sulfur. Gypsum is the most common sulfate mineral.[17] Pure gypsum is white, but other substances identified as impurities may give a wide array of https://www.propanraya.com/id/produk/eco-gypsum-ee-4050