A light, silvery-white, ductile metal with high electrical conductivity and good resistance to corrosion. Obtained from bauxite. Symbol, Al. It is the lightest of the metals in general use commercially and is the basis for light alloys used in the construction of modern aircraft and rockets; aluminum coatings are used for telescope mirrors, decorative paper, packages, and toys. The oxide, alumina, occurs naturally as ruby, sapphire, corundum, and emery.