The closest relative of carbon in the Periodic Table, silicon or silicium is named from one of the common minerals within which it occurs, namely flint, which in Latin was called "silex". After oxygen, silicon is the most abundant element in the earth's crust. Because of its great affinity for oxygen, it occurs exclusively as the oxide, namely silicon dioxide (silica) or quartz and as the hydrated oxide, silicic acid in the form of the salts of various metals. Silica may occur in the free state or mixed with other minerals in siliceous rocks notably in granites. Being one of the hardest components, silica is not as liable to disintegrative action of winds and rains as are the other components of granites.