erbium
n.
5ModL: so named (1843) by K. G. Mosander (1797-1858), Swed chemist, after Ytterby, village in Sweden where the rare-earth minerals were first found + 3IUM6 a trivalent chemical element of the rare-earth metals: symbol, Er; at. wt., 167.26; at. no., 68; sp. gr., 9.066; melt. pt., 1,529UC; boil. pt., 2,863UC