|Atomic mass||138.9055 amu|
Lanthanum was discovered in 1893.
Lanthanum is a silvery white, malleable, and ductile metal. It is soft enough to be cut with a knife. It undergoes considerable surface attack in moist air, and in finely divided form it will catch on fire at room temperature. This element is at the beginning of the lanthanide series and is also a rare-earth metal.
Commercial-grade lanthanum is obtained from monazite sand, which is a mixture of phosphates of thorium, cerium, and most of the other rare-earths. Like most rare-earth metals, lanthanum is separated from other rare earths by means of ion exchange methods.
Although it is frequently referred to as a sand, it contains very little silica. It occurs in economically important amounts in Australia, India, South Africa, Brazil, and USA (Florida, North Carolina and Virgina).
Lanthanum is used as electrodes for high-intensity, carbon-arc lights, the kind that is used in commercial motion picture projectors and searchlights. Lanthanum compounds are used in glass and ceramics, as phosphors in fluorescent lamps.
Lanthanum has some application in high-energy fuels and as a reducing agent, and as an alloy agent. It also plays an important role in the production of high-grade europium metal.