Erbium is a chemical element with the symbol Er and atomic number 68. Erbium is a rare, silvery-white metallic lanthanide (an element having an atomic number between 57 and 71). It is found solid in its natural state and is commonly found with several other elements in the mineral gadolinite. It is found in Ytterby, Sweden. Erbium was discovered by Carl Gustaf Mosander in 1843. Mosander separated yttria from gadolinite into three compounds he called erbia, terbia, and yttria. Erbia and terbia, however, were confused at that time. After 1860, terbia was renamed erbia, then after 1877 what was known as erbia, was renamed terbia. Erbium-oxide was isolated in 1905, and pure erbium metal wasn’t produced until 1934. It wasn’t until the 1990s that erbium-oxide would be cheap enough to be used as a colorant in art glass.
Erbium is never found as a free Earth element in nature. It is found bound to monazite sand ores. It was historically difficult to separate rare earth metals from one another until the invention of ion exchange techniques in the 1950s. This made it also cheaper to produce pure metals and their compounds. The principal sources of erbium come from the minerals xenotime, euxenite, and gadolinite. It has also been found recently in the clays of southern China. Two-thirds of the ore produced in China, though, is yttrium. Only about 5% is erbia. The total concentration of erbium found in the Earth’s crust is less than one ounce per ton of earth
Erbium in its pure state is pliable (easily shaped). It is very soft, yet stable in air. It does not oxidize as quickly as other rare-earth metals. The salts of erbium are rose colored. The oxidized state of erbium is called erbia. Erbium doesn’t have any known biological roles although it does stimulate metabolism. Erbium can be used as an optical medium, or for lasers and optical amplifiers. Erbium is ferromagnetic (highly magnetic to various alloys) below -425 degrees Fahrenheit. Between -425 and -315 degrees Fahrenheit it becomes antiferromagnetic (atoms point in opposite directions), and at temperatures above -315 degrees Fahrenheit, erbium becomes paramagnetic (less magnetic than ferromagnetic).
Naturally occurring erbium has 6 known stable isotopes. Erbium-166 is the most abundant (33% natural abundance). It has 29 radioisotopes with the most stable being erbium-169 with a half-life of 9.4 days. The rest have half-lives less than 50 hours, with most having half-lives less than 4 hours. The majority of theses have half-lives less than 4 minutes. Erbium has 13 meta states. The isotopes of erbium range in atomic mass from 142.9663 to 176.9541.
Erbium is used in several applications. It is commonly used as a photographic filter, and a metallurgical additive. It is used in nuclear technology as a nuclear poison. It is commonly used in its erbia state as a colorant for glass, cubic zirconia, and porcelain. It is also used in sunglasses and cheap jewelry.
Erbium compounds have little to moderate toxicity, although their toxicity has yet to be investigated in detail. The dust form of metallic erbium presents a fire and explosion hazard.