A metallic chemical element, Gd, atomic number 64 and atomic weight 157.25, belonging to the rare-earth group. The naturally occurring element is composed of eight isotopes. It is named in honor of the Swedish scientist J. Gadolin. The oxide, Gd₂O₃, in powdered form is white, and solutions of the salt are colorless. Gadolinium metal is paramagnetic and becomes strongly ferromagnetic below room temperatures. The Curie point, where this transition occurs, is about 16 K.