- the dioxide form of silicon, SiO2, occurring especially as quartz sand, flint, and agate: used usually in the form of its prepared white powder chiefly in the manufacture of glass, water glass, ceramics, and abrasives.
- the dioxide of silicon, occurring naturally as quartz, cristobalite, and tridymite. It is a refractory insoluble material used in the manufacture of glass, ceramics, and abrasives
- short for silica glass
