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.
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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].

Rare Earths: Green or not-too-green?

It's great to shrink our high-tech toys through the use of rare earths, but they have other important uses, especially in regard to the environment. The metals are used in the creation of numerous "green" items, including hybrid cars, air pollution controls, LED light bulbs and wind turbines.

Specifically, magnets made from rare earths are used in wind turbines and related items like generators, making them strong and powerful, yet light and efficient. Rechargeable batteries, which power everything from tiny e-readers to the heavy hybrid vehicles mentioned above, also use these elements, lanthanum in particular. Every Toyota Prius, for example, carries 10 pounds (4.5 kilograms) of lanthanum in its "nickel-metal hydride" battery. (Guess what the "metal" part of the name refers to? Lanthanum, of course [source: Popular Mechanics].)

Of course, rare earths aren't perfect. All rare earth ores contain uranium and thorium -- radioactive elements that become waste products when mined, and must be carefully disposed of. It also takes more chemicals to separate uranium and thorium than it does to separate base metals such as copper, zinc and lead, which isn't great for the environment [source: Think Global Green].

In China and elsewhere, lax regulations and illegal mining of rare earth metals have resulted in polluted land and water and even poisoned local inhabitants, which is obviously a major issue [source: Houses of Parliament]. The mining process uses a lot of energy, too, and can cause topsoil degradation and erosion. And finally, many high-tech gadgets made with rare earths are chucked into landfills when they're no longer useful, and researchers don't know yet if, over time, the rare earths will be released back into the environment -- and if so, what that may mean for our planet [source: Houses of Parliament, Smith].

Ultimately, though, production of rare earths continues to ramp up, suggesting that, at least for now, their innumerable environmental and societal benefits outweigh the costs. So it looks like these elements are here to stay -- at least until the next best thing is discovered.

Author's Note: What are rare earth elements, and what do they have to do with the environment?

I'll admit it: I hate science. (Math too, if you must know.) So this topic initially didn't thrill me. Until I realized it meant I finally had something science-y to discuss with my older daughter, who just graduated with a B.S. in chemistry. My daughter was familiar with the rare earth elements, and helped me to fully understand what they're all about. That personal touch made the subject much more interesting to me, and I hope that interest is reflected in this article.

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