Several varieties of gypsum are used as decorative stones. The most important, alabaster, is found as fine-grained masses in pastel shades, but is commonly stained in stronger colors.

Selenite is colorless, occasionally cut for collectors, but very soft. Satin spar is a fibrous variety, polished or cut in cabochon. Rose shapes (called "desert rose") also occur. Gypsum also comes in cat's eye effect.

Localities include Italy and England (Alabaster); Italy, Mexico, United States and Chile (Selenite).

Chemical Composition: 

Hydrated calcium sulphate

Crystal System / Forms: 

Monoclinic

Hardness: 

2

Specific Gravity: 

2.32

Lustre: 

Silky to vitreous.

Refractive Index / Birefringence: 

1.52-1.53 / 0.010

Magnification: 

• In rough, parallel fibrous structure.
• In cabochon, stain lustre.

Geological Occurrence: 

Italy and England (Alabaster); Italy, Mexico, the United States and Chile (Selenite).

Cuts & Uses: 

Cabochon