Hydration Of Anhydrite: Gypsum may also kind in the hydration of anhydrite (CaSO₄). Anhydrite is actually a calcium sulfate mineral that lacks the h2o molecules existing in gypsum. When exposed to h2o, anhydrite undergoes a hydration reaction, incorporating h2o molecules into its composition and reworking into gypsum. Impurities in refinery https://www.propanraya.com/id/produk/eco-gypsum-ee-4050