Gypsum

**Chemical composition:** CaSO₄·2H₂O

**Hardness:** 1.5 – 2

**Density:** 2.3 – 2.4 g/cm³

**Crystal system:** Monoclinic

**Luster:** Vitreous to Resinous

**Info:** Gypsum occurs in nature as flattened and often twinned crystals. A transparent variety is called selenite. A massive fine-grained white or lightly tinted variety is called alabaster, which has been often used for sculpture. Gypsum can be used also as a fertilizer and as the main constituent in many forms of plaster in building.

## Keywords
mineral gypsum texture color ornamental stone semi-precious gemstone