Silica is a refractory ceramic which is widely used in the steel and glass industries. Silica bricks are prepared by kiln-firing quartz of low impurity content at a temperature of 1450°C, thereby converting at least 98.5% of it into a mixture of the more 'open', less dense forms, tridymite and cristobalite. Size: 12 In. X 4 In. X 2 In.