One of the most abundant minerals in the Earth’s crust, quartz occurs in almost all rocks and has even been found in samples taken from the moon. A type of rock that is solely or primarily composed of quartz is known as quartzite. Predominantly formed from the metamorphism of sandstone, quartzite varies in color, but is typically white, pink, or gray. Large masses of quartzite, which are resistant to erosion, can frequently be observed in the form of mountains and hills. The rock is often quarried as a source of silica and also garners use as building material.