It is a silvery-white metal of the lanthanide series that reacts readily with air to form a dark oxide coating.

[15] Divalent europium is a mild reducing agent, oxidizing in air to form Eu(III) compounds.

In anaerobic, and particularly geothermal conditions, the divalent form is sufficiently stable that it tends to be incorporated into minerals of calcium and the other alkaline earths.

The nature of the europium anomaly found helps reconstruct the relationships within a suite of igneous rocks.

[24] Divalent europium (Eu2+) in small amounts is the activator of the bright blue fluorescence of some samples of the mineral fluorite (CaF2).

[25] The most outstanding examples of this originated around Weardale and adjacent parts of northern England; it was the fluorite found here that fluorescence was named after in 1852, although it was not until much later that europium was determined to be the cause.

Rare-earth elements are found in the minerals bastnäsite, loparite-(Ce), xenotime, and monazite in mineable quantities.

Further separation by solvent extractions or ion exchange chromatography yields a fraction which is enriched in europium.

Europium(II) reacts in a way similar to that of alkaline earth metals and therefore it can be precipitated as a carbonate or co-precipitated with barium sulfate.

[35][36][37] The mining operations at the Bayan Obo deposit made China the largest supplier of rare-earth elements in the 1990s.

The second large source for rare-earth elements between 1965 and its closure in the late 1990s was the Mountain Pass rare earth mine in California.

The bastnäsite mined there is especially rich in the light rare-earth elements (La-Gd, Sc, and Y) and contains only 0.1% of europium.

The Eu(III) sulfates, nitrates and chlorides are soluble in water or polar organic solvents.

William Crookes observed the phosphorescent spectra of the rare elements including those eventually assigned to europium.

[42] Europium was first found in 1892 by Paul Émile Lecoq de Boisbaudran, who obtained basic fractions from samarium-gadolinium concentrates which had spectral lines not accounted for by samarium or gadolinium.

[43][44][45][46][47] When the europium-doped yttrium orthovanadate red phosphor was discovered in the early 1960s, and understood to be about to cause a revolution in the color television industry, there was a scramble for the limited supply of europium on hand among the monazite processors,[48] as the typical europium content in monazite is about 0.05%.

Californian bastnäsite now faces stiff competition from Bayan Obo, China, with an even "richer" europium content of 0.2%.

Frank Spedding, celebrated for his development of the ion-exchange technology that revolutionized the rare-earth industry in the mid-1950s, once related the story of how[49] he was lecturing on the rare earths in the 1930s, when an elderly gentleman approached him with an offer of a gift of several pounds of europium oxide.

The elderly gentleman had turned out to be Herbert Newby McCoy, who had developed a famous method of europium purification involving redox chemistry.

Combining the same three classes is one way to make trichromatic systems in TV and computer screens,[51] but as an additive, it can be particularly effective in improving the intensity of red phosphor.

[10] One of the more common persistent after-glow phosphors besides copper-doped zinc sulfide is europium-doped strontium aluminate.

[58][59] An application that has almost fallen out of use with the introduction of affordable superconducting magnets is the use of europium complexes, such as Eu(fod)3, as shift reagents in NMR spectroscopy.

[60] Europium compounds are used to label antibodies for sensitive detection of antigens in body fluids, a form of immunoassay.

When these europium-labeled antibodies bind to specific antigens, the resulting complex can be detected with laser excited fluorescence.