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.
Other articles related to "rare earth element, rare earth elements, elements":
... Rare earth elements are not exchange-traded in the same way that precious (for instance, gold and silver) or non-ferrous metals (such as nickel, tin, copper ... The 17 elements are not usually sold in their pure form, but instead are distributed in mixtures of varying purity, e.g ...
Famous quotes containing the words element, rare and/or earth:
“The element running through entire nature, which we popularly call Fate, is known to us as limitation. Whatever limits us, we call Fate.”
—Ralph Waldo Emerson (18031882)
“Love brings to light the lofty and hidden characteristics of the loverwhat is rare and exceptional in him: to that extent it can easily be deceptive with respect to what is normal in him.”
—Friedrich Nietzsche (18441900)
“Oh sure, everyone goes back to the earth at some point, but life itself is a thread that is never broken, never lost. Do you know why? Because each man makes a knot in the thread during his lifetime: it is the work he has done and thats what gives life to life in the long stretch of time: the usefulness of man on this earth.”
—Jacques Roumain (19071945)