Silicates:- Metal silicates having wide range of structures ranging from simple monomer to complex polymer is the general term given to metal ion attached to basic unit of tetrahedral nature of silicate ion. A silicate in general has Si-O bond and possesses a complex network solid having silicate ion groups, in cyclic groups, in infinite chains or infinite sheets given different structure to silicates such as chain silicates, ring silicates, cyclic silicates, sheet silicates, three dimensional silicates etc. A large percentage of the earth’s crust consists of silicate minerals. As SiO₂ in earth crust it exists as silica, sand, quartz and flints. Some of the other important silicate minerals are asbestos (calcium magnesium silicate i.e., (CaMgSi₂O₆), feldspar (potassium aluminum silicate, (KAlSi₃O₈), zeolite (sodium aluminium silicate, Na₂Al₂Si₂O₈.xH₂O) and diopside (magnesium calcium silicate, (MgCaSi₂O₆).