Minerals and Metals in Ancient India v2.c47.73

v2.c47.73

*Gypsum* : CaSO₄, 2H₂O. Greek *gypsos* (= plaster). Hardness 1.5-2.0 Varieties: Crystallized or *Selenite* is colourless or transparent. *Alabaster* is a massive fine-grained variety, white or delicately shaded. *Rock gypsum* may have silica, clay or calcium carbonate as impurities.