Lanthanum

Lanthanum is a soft, silvery-white metal in the lanthanide family of rare-earth elements. Its shiny surface tarnishes in air as it reacts with oxygen. Despite the name rare earth, lanthanum is more abundant in Earth's crust than lead. It occurs combined with other elements in minerals such as monazite and bastnäsite, alongside other rare-earth metals. Producers chemically process these ores and separate the lanthanum compounds; electricity passed through molten salts can then release the metal. Lanthanum oxide helps make special glass for camera and telescope lenses that bends light strongly while limiting the separation of colors. Lanthanum-containing alloys can also store hydrogen and are used in rechargeable nickel–metal hydride batteries, including those in some hybrid cars.