An Etymological Dictionary of Astronomy and Astrophysics

A widely found mineral of silicon dioxide SiO₂, which is used as an ore of → silicon. It is
a hard, white, or colorless crystalline compound with a high melting point, occurring abundantly as quartz, sand, flint, rock crystal, etc.

See also: From L. silic- stem of → silex “hard stone, flint, boulder.”