Source : Webster's Revised Unabridged Dictionary (1913)

Phenacite \Phen"a*cite\, n. [Gr. ?, ?, impostor, deceiver.]
   (Min.)
   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.