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What are rare earth elements – and what do they have to do with the environment?

The elements of the lanthanide series on the periodic table are considered rare earth elements. See more green science pictures.
Steven Taylor/Photographer's Choice/Getty Images

Rare earths get no respect. Stuck near the bottom of the periodic table of the elements, and given unpronounceable names like praseodymium and ytterbium, they have nowhere near the glamour and popularity that oxygen, nitrogen, carbon and the other chart-toppers do. Heck, even zirconium -- used to create the oft-mocked cubic zirconia diamond simulant -- fares better than the rare earths. The irony of all this is that most people use products made with rare earths daily. In fact, you could say we wouldn't be able to live without them, as they're found in most high-tech gadgets: cell phones, computers, iPods and more.

So what, exactly, are these things? There are 17 rare earth elements, according to a widely accepted definition, all of which exhibit similar chemical properties: the elements in the lanthanide series -- lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium -- plus yttrium and scandium, classified as "transition metals" [source: Houses of Parliament]. (However, some scientists may exclude scandium, or both scandium and yttrium, from the rare earths grouping, depending on how similar they feel those two elements are to the lanthanides.) These elements, also called rare earth metals, were discovered in 1787 by chemist Lieutenant Carl Axel Arrhenius, after he found a strangely heavy, black rock in a quarry in Ytterby, Sweden, which he named ytterbite [sources: Vanderkrogt, Think Global Green].

These metals aren't really rare -- they're found in abundance the world over. People consider them rare, though, because they're scattered in tiny bits all over the planet, not clustered together in veins, like copper. Actually, they are found in clusters -- but with other rare earths, not just their particular kind. This means they have to be harvested, then separated out into each single element, which is difficult and costly. In fact, when the elements were initially discovered, and scientists weren't sure what to do with them yet, they were mined together as a group. This mish-mash of elements was called "mischmetal" [source: Popular Mechanics]. Really.

For decades, scientists noodled over these elements, eventually realizing their great potential. For one thing, rare earths have wonderful magnetic and conductive properties, allowing us to shrink our techie devices. Remember the 1970s-era Sony Walkman, the first portable music device? That compact player was made possible partly because it contained a small, strong magnet made from samarium. Today, samarium-based magnets have been replaced by even smaller, stronger neodymium ones -- hence the Walkman's diminutive descendant, the iPod [source: Popular Mechanics, Lynas Corp.]. Rare earths also shine in the defense arena, where they're used to create everything from night-vision goggles to precision-guided weapons.

The U.S. once led the world in rare earth processing, but today that distinction belongs to China, which benefited from government subsidies in the 1980s and 1990s that enabled them to flood the international market with cheap rare earths. As China's own need for them has grown, however, they're not selling as much to the rest of the world, and a shortage is looming. The U.S. has restarted its former production facility, and eventually may again be able to cover its own consumption of rare earth metals [source: National Geographic].