Ytterbium a soft, silvery metal is part of the Lathanide series. In nature, it has seven isotopes, but is difficult to separate from the other rare earth elements with which it is found. Discovered in 1878 by Jean C.G. Marignac, Ytterbium is named for the Ytterby, Sweden; the town where it was discovered. Three other elements are named for Ytterby: Erbium, Terbium, and Yttrium. There are very few known uses for Ytterbium.