Hydration Of Anhydrite: Gypsum can also form with the hydration of anhydrite (CaSO₄). Anhydrite can be a calcium sulfate mineral that lacks the drinking water molecules existing in gypsum. When subjected to water, anhydrite undergoes a hydration reaction, incorporating drinking water molecules into its framework and reworking into gypsum. Rehydration: https://www.propanraya.com/id/produk/eco-gypsum-ee-4050