Quartz is the second most abundant mineral in the Earth's continental crust after feldspar with formula SiO2. Quartz has a hardness of 7 on the Mohs scale and a density of 2.65 g/cm . Milky quartz may be the most common variety of crystalline quartz .white colour may be caused by minute fluid inclusions of gas and/or liquid trapped during the crystal formation. Due to presence of more than 95% Silica, it is referred to as silicon dioxide or silica.
