Shiny steel-gray metal. m.p. 1522±8 ºC; 2772±14.5 ºF b.p. 3338 ºC; 6040 ºF density 4.469 g/cc (25 ºC); 278.991 pound/cubic foot (77 ºF)	memory peg
	1794 Johan Gadolin, Finland
	Ytterby, village in Sweden (just as Ytterbium, Erbium, and Terbium!) named by Anders Gustaf Ekeberg

The rare earths are so very much alike and occur closely associated in such complex minerals that it was extremely difficult to separate them. They were all obtained, however, by elaborate and laborious fractionation of two mixtures, the "yttria" of Gadolin and the "ceria" of Klaproth, Berzelius, and Hisinger, originally believed by their discoverers to be pure oxides. (M.E. Weeks 1968, p. 667).

Elements discovered in yttria
(Click on the yellow circles for the element pages).
(Click here for the ceria group).

The chemist Lieutenant Carl Axel Arrhenius (1757-1824), student of the Swedish chemist Berzelius, found in 1787 in the dumps of the Ytterby quarry (for information on Ytterby and its quarry, see Ytterbium) an interesting find, an exceptionally heavy piece of black broken rock. He named it ytterbite after the location with the standard suffix -ite added to indicate a mineral. This stone was sent to, among others, Johan Gadolin (1760-1852), professor at Åbo University.

Gadolin found that the "black stone of Ytterby" was composed of 38% of a new "earth type" ("earths" are compounds of elements, usually oxides). He concluded his analysis in 1794 and named this new earth ytterbia (note). His analysis was confirmed three years (1797) later when Anders Gustaf Ekeberg (1767-1813) analysed a larger sample. Ekeberg shortened the name to yttria. In the decades after Antoine Lavoisier developed the new chemistry built on the concept that earths could be reduced to their elements, the discovery of a new earth (with name ending in "a") was regarded as equivalent to discovering the element within. Thus the element reducible from the earth yttria would be Yttrium.

However, yttria was in fact it was a mixture of a number of metal oxides. In 1843, Carl Gustav Mosander (1797-1858) separated yttria into three parts, one of which kept the original name:

1. Yttria (with a colorless salt and colorless oxyde),
2. Erbia (yellow oxyde, colorless salt), and
3. Terbia (rose oxyde, red salt).
   (Later Erbia and Terbia were interchanged).

To commemorate Johan Gadolin, the mineral was renamed by Martin Klaproth into gadolinite.

In more than a century of research, ten new elements were found in Gadolin's yttria (see table above). Six of these were named after the location where gadolinite was found, and four of these six after the small village: Erbium, Terbium, Ytterbium, and Yttrium; Holmium is named after Stockholm, and Scandium and Thulium were named after Scandinavia respectively. The other new elements are Gadolinium, Dysprosium, and Lutetium.

Until the 1920s the chemical symbol Yt was used (note).

In 1911 Carl Auer von Welsbach wrote that it was possible to split Terbium in two new elements and Thulium in three new elements (note). The Viennese photo-historian, scientist, and teacher Josef Maria Eder (1855-1944) announced the discoveries of these five and prematurely gave them a name: from Thulium: Neothulium ("New Thulium"), Denebium (after Deneb, the brightest star in the constellation Cygnus - the Swan), Dubhium (after Dubhe, the brighter and northernmost of the Big Dipper's two pointer stars showing the way to Polaris, Dubhe is at the far edge of the Big Dipper), and from Terbium: Eurosamarium and Welsium (after his friend Carl Auer von Welsbach). The presence of these elements had been guessed on the evidence of spectra lines, but it was not possible for him to isolate the elements not even traces of them. His results remained unconfirmed. Today we can say that he recorded spectra of a complex mixture of already known elements (rare earth elements) (note).

• Mary Elvira Weeks, Discovery of the Elements, comp. rev. by Heny M. Leicester (Easton, Pa.: Journal of Chemical Education, 1968), pp. 667-699.
• Seltene Erden. Gmelins Handbuch der anorganische Chemie, 8. Aufl.; System-Nummer 39 (1938).
• Lauri Niinistö, "Discovery and Separation of Rare Earths". In Rare Earths, ed. Regino Sáez Puche & Paul A. Caro, 25-42. Madrid: Editorial Complutense, 1997.
• Peter B. Dean, and Kirsti I. Dean, "Sir Johan Gadolin of Turku: The Grandfather of Gadolinium." (on-line PDF file).