PHENACITE

Etymology

Noun

phenacite (plural phenacites)

(mineral) A clear glassy mineral, a silicate of glucina, occurring in rhombohedral crystals and sometimes used as a gem.

Source: Wiktionary

Phen"a*cite, n. Etym: [Gr. (Min.)

Definition: A glassy colorless mineral occurring in rhombohedral crystals, sometimes used as a gem. It is a silicate of glucina, and receives its name from its deceptive similarity to quartz.

Source: Webster’s Unabridged Dictionary 1913 Edition