The rare earth elements that play an important role in everything from electric car batteries, to LED lighting, to surgical lasers, aren't actually rare. The vast majority of them come from China right now, but that's not because China has them and other countries don't. In fact, the US and Australia also have large deposits of rare earths. Instead, rare earth elements come from China because China is willing to cheaply mine and process them, which can be extremely polluting. The more protections against pollution that you put in place, the more expensive the rare earths become, which is how the US got priced out of that game.
All of that is important background information to help you understand why a proposal to mine and process rare earth elements in Greenland is so controversial. On the one hand, it could bring economic and political independence to the country (which still relies heavily on Denmark), and provide jobs in a really rough economyu. On the other hand, actually challenging China's supremacy in this business means cutting costs in ways that would likely have lasting, negative impacts on the land.
Maggie Koerth-Baker is the science editor at BoingBoing.net. She writes a monthly column for The New York Times Magazine and is the author of Before the Lights Go Out, a book about electricity, infrastructure, and the future of energy. You can find Maggie on Twitter and Facebook.