Silicates are metal derivatives of silicic acid. Silicates are formed by heating metal oxide or metal carbonate with sand
${\mathrm{Na}}_2\mathrm{C}{\mathrm{O}}_3\underset{{\mathrm{SiO}}_2}{\overset{\mathrm{fused}\mathrm{with}\mathrm{sand}}{\to }}{\mathrm{Na}}_4{\mathrm{SiO}}_4,{\mathrm{Na}}_2\left({\mathrm{SiO}}_3\right)\mathrm{etc}$
A silicate in general has $\mathrm{Si}-\mathrm{O}$ bond and possesses a complex network solid having silicate ion ${\mathrm{SiO}}_4^{4-}$ as the basic structural unit. These silicates occurs singly or by sharing oxygen atom is small groups, in cyclic groups, in infinite chains or infinite sheets giving different structures to silicates such as chain silicates, ring silicates, cyclic silicates, sheet silicates, three dimensional silicates etc.