Aluminium

Aluminium is a chemical element with the symbol Al and atomic number 13. It is a silvery-white, soft metal that is the third most abundant element in the Earth's crust by mass and the most abundant metal. It is rarely found free in nature and occurs primarily in the minerals bauxite and cryolite. Aluminium is notable for its low density and high strength-to-weight ratio, its excellent corrosion resistance due to a self-forming oxide layer, and its good electrical and thermal conductivity.

Most aluminium is produced commercially by refining bauxite to alumina through the Bayer process, followed by electrolytic reduction of alumina in molten cryolite via the Hall-Héroult process. The production is energy-intensive, and recycling aluminium requires only a fraction of the energy of primary production.

The metal is widely used in packaging, construction, transportation, and electrical applications. Common forms include ingots and extrusions, as well as alloys based on magnesium and silicon that improve strength. Aluminium's properties also enable use in aircraft and spacecraft, automobiles, window frames, cans, foils, and cookware.

Historically, aluminium was identified in 1825 by Hans Christian Ørsted and subsequently isolated in purer form by Friedrich Wöhler in 1828. The element was named aluminium (and the American spelling aluminum is also widely used) with the International Union of Pure and Applied Chemistry recognizing aluminium as the preferred spelling internationally.

Recycling plays a major role in reducing environmental impact, since recycled aluminium can be re-melted with substantially less energy than primary production.