Hydration Of Anhydrite: Gypsum might also sort with the hydration of anhydrite (CaSO₄). Anhydrite is a calcium sulfate mineral that lacks the water molecules present in gypsum. When exposed to h2o, anhydrite undergoes a hydration response, incorporating h2o molecules into its structure and transforming into gypsum. Impurities in refinery gypsum https://www.propanraya.com/id/produk/eco-gypsum-ee-4050