A mineral that is a component of lapis lazuli, but is also sometimes used alone as a gemstone. It is transparent to translucent, of vitreous to greasy lustre,and of various colours but mainly blue, and sometimew with specks of pyrites. Purplish varieties tend to lose colour when warmed or exposed to sunlight. The massive form is sometimes polished bytumbling or is cut en cabochon or as beads.
Sodalite

Sodalite
A mineral that is a component of lapis lazuli, but is also sometimes used alone as a gemstone. It is transparent to translucent, of vitreous to greasy lustre,and of various colours but mainly blue, and sometimew with specks of pyrites. Purplish varieties tend to lose colour when warmed or exposed to sunlight. The massive form is sometimes polished bytumbling or is cut en cabochon or as beads.
References
From: An Illustrated Dictionary of Jewelry, autor: Harold Newman, publishers: Thames and Hudson



