Mar 12, 2011· INTRODUCTION Gypsum is a mineral that is mined in various parts of the world. The word gypsum derived from Greek word meaning ¶to cook· referred to burnt or calcined mineral. Chemically it is CaSo4;2H2O i.e. calcium sulphate dihydrate. Three types of gypsum products are available in dentistry ² 1. Model plaster 2.