A silver-white metallic element that is
the prototype and second most abundant member of the lanthanide
series. First identified by C. G. Mosander in Stockholm in 1839, its name
comes from the Latin lanthana meaning "to lie hidden."
Its chief ores are monazite and bastnaesite.
Soft, malleable, and ductile, lanthanum
is used as a catalyst in cracking
crude oil, in alloys, and to manufacture optical
glasses. Its most common isotope
is 139La (99.91%).
|relative atomic mass