The lanthanides have very similar chemical properties, and tend to occur together in nature. As a consequence, they were discovered in samples of the same kinds of minerals. In 1794, the Finnish scientist, Johan Gadolin, succeeded in isolating what he believed to be the oxide of a new element, and this supposed-oxide was named yttria, after the Swedish village of Ytterby where it was dicovered. Yttria, however, was subsequently shown to be a mixture of several oxides, and after Carl Gustav Mosander isolated yttrium oxide from the mixture in 1843, it eventually yielded a further nine oxides.
Ceria, another mixture mistaken for a single oxide, was separated independently by the German chemist, Martin Heinrich Klaproth, and the Swedish chemist, J÷ns Jacob Berzelius, in 1803. Between 1839 and 1901, following Mosander's recognition of its true nature, six oxides were isolated from the mixture.
From these two mixtures of minerals - yttria and ceria - were derived thirteen of the fourteen lanthanides, and the related elements, scandium, yttrium and lanthanum. Four of the elements - yttrium, ytterbium, terbium and erbium - were named after the village of Ytterby. Promethium was discovered in 1945 in the fission products of a nuclear reactor.
