An Etymological Dictionary of Astronomy and Astrophysics

A metallic chemical element; symbol Tb. Atomic number 65; atomic weight 158.9254; melting point 1,356°C; boiling point 3,123°C; specific gravity about 8.25. Terbium was discovered by the Swedish surgeon and chemist Carl-Gustav Mosander in 1843 in an yttrium salt, which he resolved into three elements. He called one yttrium, a rose colored salt he called terbium and a deep yellow peroxide he called erbium.

See also: From the “village of Ytterby” in Sweden, where the mineral ytterbite (the source of terbium) was first found.