Calcium sulphate is an inorganic white solid with the formula CaSO4. It occurs naturally as a mineral and is also produced synthetically, often as a by-product (e.g. from desulphurisation). The compound exists in three levels of hydration: anhydrous (as mineral anhydrite), dihydrate (gypsum or as mineral selenite) and hemihydrate (Bassanite or plaster of Paris).All forms are poorly soluble in water and cause permanent hardness in water.
|Molar Weight||172.17 g/mol (dihydrate)|
|Melting Point||1,460°C (anhydrous)|
|Flash Point||non flammable|
|Specific Gravity||2.32 g/cm³ (dihydrate)|
Synonyms: Gypsum, E516, Plaster of Paris, Anhydrite, Selenite, Alabaster
Chemical Formula: CaSO4
CAS Number: 7778-18-9 (anhydrous), 10034-76-1 (hemihydrate), 10101-41-4 (dihydrate)