This mineral, rarely used as a gem stone, is 7.5 to 8 in hardness; specific gravity, 2.96 to 3; lustre, vitreous; transparent to semi-translucent, doubly refractive, it does not melt before the blow-pipe, and contains:

Phenacite occurs colorless, and also bright wine-yellow inclining to red, and brown. This stone is found in Russia, Mexico, and Alsace.

The colorless or transparent variety approaches the diamond in brilliancy, especially under artificial light.