The element with atomic number 13 that is the most abundant metal in Earth’s crust is aluminum. In British and IUPAC spelling it is written aluminium, but “aluminum” is the standard North American form; both names refer to the same element, symbol Al.
Aluminum makes up about 8.2% of the mass of Earth’s continental crust, ranking third among all elements behind oxygen and silicon. It is widespread because it bonds readily with oxygen and becomes part of minerals such as feldspars and other aluminosilicates. That same chemical reactivity means aluminum is rarely found as free metal in nature.
Most commercial aluminum comes from bauxite, which is processed into alumina and then reduced by electrolysis. Hans Christian Ørsted announced its discovery in 1825, but large-scale production became practical after the Hall–Héroult process was developed independently by Charles Martin Hall and Paul Héroult in 1886.
A common mix-up is iron: iron is more widely produced and familiar, but aluminum is more abundant in the crust. Aluminum’s low density and protective oxide coating explain its use in aircraft, cans, foil, construction, and electrical wiring.