The rare earth elements are a class of 17 chemical elements, grouped together because of their chemically similar properties. They are usually soft, malleable and react easily with other chemicals, especially at higher temperatures. The rare earth elements are lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. The group also includes scandium, yttrium, and thorium, which have similar chemical properties.
Despite their name, the rare earth elements are not especially rare; many of them are as abundant as more common elements like nickel, copper, silver, lead and tin. But they can be difficult to harvest, since they are contained in other naturally occurring minerals as trace elements, and must be separated out. This can be a costly and labor-intensive process, so they cannot be mined in large quantities. They are most commonly found in the minerals bastnaesite, monazite, and xenotime.
There are numerous ways we use rare earth elements. They are used for polishing glass and optical lenses; as additives to strengthen soft metals; in permanent magnets; and as ceramics and as dyes for glazes and coatings. The phosphors, which glow when struck by light or an electrical charge, are used in color televisions and in fluorescent lighting. Rare earths can also be found in nuclear detectors, lasers, electronic components, jewelry, and as anti-corrosive additives in paints.