cerium

Malleable and ductile, grey, metallic element, atomic number 58, relative atomic mass 140.12. It is the most abundant member of the lanthanide series, and is used in alloys, electronic components, nuclear fuels, and lighter flints. It was discovered in 1804 by the Swedish chemists Jöns Berzelius and Wilhelm Hisinger (1766–1852), and, independently, by German chemist Martin Klaproth. The element was named after the then recently discovered asteroid Ceres.