The element with atomic number 70 named after the Swedish village Ytterby is ytterbium. Its chemical symbol is Yb, and it is a silvery metal in the lanthanide series of rare-earth elements.
Swiss chemist Jean Charles Galissard de Marignac identified a new component in the rare-earth material then called erbia in 1878. He named the material ytterbia after Ytterby, a village on the Swedish island of Resarö known for its unusual concentration of mineral discoveries.
Ytterbium was not immediately isolated as a pure metal. In 1907, Georges Urbain separated ytterbia into ytterbium and lutetium, while Carl Auer von Welsbach made an independent separation. Nearly pure ytterbium metal was finally produced in 1953.
Ytterby is an especially important place-name in chemistry: yttrium, terbium, erbium, and ytterbium all take their names from the village. That makes the four names easy to confuse. Ytterbium is also unusual among lanthanides because it readily forms stable compounds in both +2 and +3 oxidation states.