(symbol Gd., atomic weight 157.3), one of the rare earth metals (see Erbium). The element was discovered in 1880 in the mineral samarskite by C. Marignac (Comptes rendus, 1880, 90, p. 899; Ann. chim. phys., 1880 [5] 20, p. 535).
G. Urbain (Comptes rendus, 1905, 140, p. 583) separates the metal by crystallizing the double nitrate of nickel and gadolinium. The salts show absorption bands in the ultra-violet. The oxide Gd203 is colourless (Lecoq de Boisbaudran).