Rare Earth Element
As defined by IUPAC, rare earth elements ("REEs") or rare earth metals are a set of seventeen chemical elements in the periodic table, specifically the fifteen lanthanides plus scandium and yttrium. Scandium and yttrium are considered rare earth elements since they tend to occur in the same ore deposits as the lanthanides and exhibit similar chemical properties.
Despite their name, rare earth elements (with the exception of the radioactive promethium) are relatively plentiful in the Earth's crust, with cerium being the 25th most abundant element at 68 parts per million (similar to copper). However, because of their geochemical properties, rare earth elements are typically dispersed and not often found concentrated as rare earth minerals in economically exploitable ore deposits. It was the very scarcity of these minerals (previously called "earths") that led to the term "rare earth". The first such mineral discovered was gadolinite, a compound of cerium, yttrium, iron, silicon and other elements. This mineral was extracted from a mine in the village of Ytterby in Sweden; several of the rare earth elements bear names derived from this location.
Read more about Rare Earth Element: List, Abbreviations, Discovery and Early History, Origin, Geological Distribution, Global Rare Earth Production
Famous quotes containing the words rare, earth and/or element:
“Bryan is the least of a liar I know in public life. I have always found him direct and honest, and he never goes back on what he has said to me in private—a rare thing, if found, in public men. I found him purely frank.”
—William Howard Taft (1857–1930)
“Now Morn her rosy steps in th’ eastern clime
Advancing, sowed the earth with orient pearl.”
—John Milton (1608–1674)
“Justice has its anger, my lord Bishop, and the wrath of justice is an element of progress. Whatever else may be said of it, the French Revolution was the greatest step forward by mankind since the coming of Christ. It was unfinished, I agree, but still it was sublime. It released the untapped springs of society; it softened hearts, appeased, tranquilized, enlightened, and set flowing through the world the tides of civilization. It was good. The French Revolution was the anointing of humanity.”
—Victor Hugo (1802–1885)