Not to mention rare elements such as lanthanum, cerium, and neodymium, essential to modern technology and commanding high prices.
metallic rare earth element, 1841, coined in Modern Latin by Swedish chemist and mineralogist Carl Gustav Mosander (1797-1858), who discovered it in 1839, from Greek lanthanein "to lie hidden, escape notice," from PIE root *ladh- "to be hidden" (see latent). So called because the element was "concealed" in rare minerals.
lanthanum lan·tha·num (lān'thə-nəm)
A soft malleable metallic rare-earth element used in glass manufacture. Atomic number 57; atomic weight 138.91; melting point 920°C; boiling point 3,455°C; specific gravity 6.145 (at 25°C); valence 3.
A soft, malleable, silvery-white metallic element of the lanthanide series. It is used to make glass for lenses and lights for movie and television studios. Atomic number 57; atomic weight 138.91; melting point 920°C; boiling point 3,469°C; specific gravity 5.98 to 6.186; valence 3. See Periodic Table.