GEOLOGY

Detailed explanation-1: -We write the formula as SiO2 because the Si and O atoms are found in that ratio, and define Z = 3, where Z = number of formula units in a unit cell. In a unit cell of cristobalite there are 4 Si and 8 O atoms, Si4O8, Z = 4.

Detailed explanation-2: -Silica, Cristobalite is a colorless, odorless, crystalline (sand-like) solid. It is used in making water glass, refractories, abrasives, ceramics, and enamels, and in scouring and grinding compounds.

Detailed explanation-3: -Cristobalite forms spontaneously (within bodies) at temperatures above 1100C from very fine quartz found in some clays, from finely ground silica powder and from molecular silica liberated during the formation of mullite from kaolin.