Elementymology & Elements Multidict

The Discovery and Naming of the Rare Earths

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).

As defined by IUPAC, rare earth elements or rare earth metals are a collection of seventeen chemical elements in the periodic table, namely Scandium (no. 21), Yttrium (no. 39), and the fifteen lanthanoids (nos. 57-71). The term "rare earth" arises from the rare earth minerals from which they were first isolated, which were uncommon oxide-type minerals (earths) found in Gadolinite extracted from one mine in the village of Ytterby, Sweden. However, with the exception of the highly-unstable Promethium, rare earth elements are found in relatively high concentrations in the earth's crust, with Cerium being the 25th most abundant element in the earth's crust at 68 parts per million.

YTTERBIA

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

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

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 oxide),
2. Erbia (yellow oxide, colorless salt), and
3. Terbia (rose oxide, 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).

Peter van der Krogt in Ytterby, Summer 2009.

Click here for more photos

P.S. The name Ytterby is composed from ytter = outer, and by = village, and means 'outer village', probably since it is located on the outermost point of the island of Resarö (see the map).

CERIA

They isolated an earth similar to yttria but recognized it was distinct. They gave the new earth the name ceria in honour of Ceres, the first asteroid, discovered two years previous, in 1801, by Giuseppi Piazza. Ceres was in Roman mythology the goddess of agriculture.

Their report was sent to Adolph Ferdinand Gehlen (1775-1815) in Germany to be published in his Neues Allgemeines Journal der Chemie. In order to establish priority, it was also printed in Swedish as a small pamphlet issued in only 50 copies, which are now of extreme rarity.

Indepently, Martin Heinrich Klaproth (1743-1817) analyzed tungsten from Bastnäs, he called the new earth ochroite. Klaproth presented also his results in Gehlen’s Journal, where his article appeared in an issue just before that containing the report of Hisinger and Berzelius.

It is not known at which exact time Gehlen received each paper for publication, but in his letter to Hisinger in May 1804 Gehlen gives Berzelius and Hisinger the honor of having discovered a new metal and as a consequence, their suggested name has prevailed. Klaproth suggested the more correct name Cererium, but this name was not accepted. Nowadays it is generally accepted that the discovery took place simultaneously and independently. Hisinger, Berzelius and Klaproth are usually named as co-discovers of Cerium.

Thirty-six years later, in 1839, Mosander showed that the Cerium oxide isolated by these researchers was composed of at least two oxides, for one of which he retained the name ceria and the second he called lanthana, which subsequently in 1842 was shown to consist of lanthana and the new earth didymia. Mosander announced the results of his research in a paper held in July 1842 in Stockholm. An English translaten was published in the Philosophical Magazine, and after this a German version in Poggendorf's Annalen: "Ueber die das Cerium begleitenden neuen Metalle Lanthanium und Didymium, so wie über die mit der Yttererde vorkommenden neuen Metalle Erbium und Terbium" (On the new metals Lanthanum and Didymium, accompanying Cerium, and on the metals Erbium and Terbium occuring with yttria) (note) (see scheme above, and further Lanthanum).

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).

J.F. Spencer, The metals of the rare earths (London 1919) ends his Introduction with "some short account of work which has resulted in the announcement of new elements that have either been shown not to exist or have not been substantiated by investigators other than the original discoverer" (p. 11-12, with his original notes, and some notes in italics by me):

The earliest of these announcements was made in 1811 by Thomas Thomson (96), who asserted the existence of an element junonium in allanite [See also Cadmium]. Scheerer (97) and Thomson himself (1818) showed, however, that an error in the analytical work was responsible for the belief in the existence of this element.
An element vestium was announced in the same year by Gilbert (98), but nothing further has been heard of this substance [See also Cadmium].
In 1879 Tellef Dahll (99) announced the discovery of norwegium, which was stated in 1880 by Prochazka (100) to be present in American lead, and which, according to Blomstrand (101) and Rammelsberg, consisted of impure bismuth [See also Hafnium].
Linnemann (102) announced the discovery of austrium in orthite, which Lecoq de Boisbaudran (103) proved to be gallium.
Chroustschoff (104) announced the discovery of russium in monazite.
Damarium (105) was announced by Lauer and Antsch in 1890 [discovered in Damara Land, South Africa], and masrium by Richmond and Off, (106) the latter being an element with properties resembling glucinum and calcium.
In 1896 Barriere (107) found lucium in monazite; this was stated by Chroustschoff to be very like russium, and was shown by Crookes to be yttrium mixed with didymium, erbium and ytterbium. Monium, afterwards re-named victorium, was announced in 1900 by Crookes (108). This was obtained by partial decomposition of the nitrates of yttrium earths by heat, followed by fractional crystallisation of the oxalates. Baur and Marc, (63) however, in 1901, characterised victorium as a mixture of known earths from an examination of its phosphorescence spectrum.
Baskerville (110) separated two radio-active elements from thorium, in 1901, which he termed carolinium and berzelium.
Hofmann and Prandtl (115) isolated from Norwegian euxenite an earth which they named euxenium. They determined its atomic weight and obtained a value 177.75. Whether such an element exists or not is an open question.
In addition to the foregoing, there have been announced all too prematurely and on insufficient evidence the following substances, kosmium and neokosmium by Kosmann (111) in 1896 [this was a joke, see the 'Didnot' page], and dämonium by Rowland (112) in 1894.
The mere fact that so many unconfirmed or disproved statements of discoveries have been made in this field of work is perhaps the best evidence that can be offered of the extreme difficulty of the investigation of the rare earths.

All these discoveries of new elements within a few years caused some comments of unbelief. That of the science editor of the American magazine the Manufacturer and builder, published July 1880, follows:

" NEW (?) METALLIC ELEMENTS.

While on tine one hand the researches of physicists are accumulating facts to demonstrate that the so-called chemnuical elements are not essentially simple bodies, the attention of chemists of late appears to have been chiefly directed to the work of discovering and adding more elements to the already formidable list. The number of alleged discoveries of this kind announced during the past year or so, is entirely without parallel. As nearly as we recall them, we have had announced to us —Samarium, Ytterbium, Philippium, Decipium, Holmium, Thulium, Mosandrium, Scandium, Norwegium, Vesbium, Ouralium, and several others that have not been dignified with names.

Many of these have been named simply upon the very slender evidence of «absorption spectra,» and none, so far as we know, have been isolated. And so rapidly have announcements of these discoveries followed each other, that, as some of the investigators were working with the same (or similar) material, it is almost certain that several of the new announcements have been duplicated. The subject has been so much complicated by the great number of «preliminary annnouncements,» that chemists have ceased their efforts to decide on the genuineness of most of them, and have, by mutual consent, settled down to wait quietly umutil some acknowledged master of the subject shall have thoroughly overhauled the mass of complicated and often conflicting evidence that has been published, and sifted the wheat from the chaff. While it is certain that some of these alleged discoveries are without substantial foundidation, and that some have been duplicated, it is equally certain that others will be found to be real acquisitions to science.

Late reports in the French journals advise us that Delafontaine, a chemist of acknowledged eminence, whose name is prominenthy identified with several of these discoveries, has undertaken the laborious task of examining the claims of these new applicants for admission to the list of elements. He announces his belief that the earth's Ytterbia, Decipia and Philippia, are real additions to science, and considers as doubtful a number of others whose existence has been affirmed purely on the strength of absorption spectra. The examination which Delafontaine has instituted will probably be taken up by others, and we may soon hope to have the merits of these alleged discoveries properly estimated by the test of severe criticism." (note).

The Manufacturer and Builder, and other journals, are on-line available on The Nineteenth Century in Print: the Making of America in Periodicals.

• Mary Elvira Weeks, Discovery of the Elements, comp. rev. by Heny M. Leicester (Easton, Pa.: Journal of Chemical Education, 1968), pp. 525-532 & 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.
• Lauri Niinistö, "Swedish Contributions to the Discovery of Elements: Part 2: The Work of Berzelius." ERES Newsletter, vol. 10, no. 1 (31 August 1999). (on-line).
• Peter B. Dean, and Kirsti I. Dean, "Sir Johan Gadolin of Turku: The Grandfather of Gadolinium." (on-line PDF file).

© Peter van der Krogt