phenakite

noun

phen·​a·​kite ˈfe-nə-ˌkīt 

ˈfē-

variants or phenacite

ˈfe-nə-ˌsīt 

ˈfē-

: a hard glassy mineral that consists of a silicate of beryllium and occurs especially in rhombohedral crystals

Word History

Etymology

German Phenakit, from Greek phenak-, phenax deceiver; from its being easily mistaken for quartz

First Known Use

circa 1834, in the meaning defined above