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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
exhange methods.
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.