Meaning of lanthanum

lan•tha•num

Pronunciation: (lan'thu-num), [key]
— n. Chem.
  1. a rare-earth, trivalent, metallic element, allied to aluminum, found in certain minerals, as monazite. Symbol: La; at. wt.: 138.91; at. no.: 57; sp. gr.: 6.15 at 20°C.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.
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