Commercial glasses are made by the fusion of silica, the primary ingredient (2) alkaline fluxes, which may contain soda, potash or both and (3) stabilizing ingredients which may be an oxide of Ca, Mg, Ba, Zn, A1, Pb or Bo or two of them. Different glasses are made by changing the percentage in formula and by the way of manufacture Glasses used in building construction are window or sheet glass, plate and rolled sheet glass and glass tiles and glass block Glass making materials are (1) glass formers which are oxides of Si, Bo and P(2) glass modifiers which are Na, K, Fe, Ca, Ba, Mg, A1, Zn and Pb and (3) intermediates which is alumina. For chemical treatment, sand, soda ash, limestone, dolomite, feldspar are used Pakistan is rich in these materials.