ETYM New Lat., from Latin silex, silics, a flint.
A white or colorless vitreous insoluble solid; various forms occur widely in the earth's crust as quartz or cristobalite or tridymite or lechartelierite; SYN. silicon oxide, silicon dioxide.
Silicon dioxide, SiO2, the composition of the most common mineral group, of which the most familiar form is quartz. Other silica forms are chalcedony, chert, opal, tridymite, and cristobalite.
Common sand consists largely of silica in the form of quartz.