Cerium is a soft, silvery, ductile metal which easily oxidizes in air. Cerium was named after the dwarf planet Ceres (itself named for the Roman goddess of agriculture). Cerium is the most abundant of    the rare earth elements, making up about 0.0046% of the Earth's crust by weight.

Commercial applications of cerium are numerous. They include catalysts, additives to fuel to reduce emissions and to glass and enamels to change their color. Cerium oxide is an important component of glass polishing powders and phosphors used in screens and fluorescent lamps.