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.
From L. silic- stem of → silex "hard stone, flint, boulder."
A common rock-forming → mineral belonging to a group formed from → silicon and → oxygen combined with various elements and classified by their crystalline structures. SiO4 in the shape of a tetrahedron is the main component of the group. It has been estimated that about 95% of the Earth's crust is made up of silicate minerals. A salt of → silicic acid.