Kyle Wiens of iFixit fame has taken a trip to what is the only rare earth metals mine in North America, in the Mojave Desert, and published his findings on The Atlantic. There are seventeen rare earth minerals, and, unlike their name implies, they are not exceedingly rare, they're just dispersed about the earth in tiny amounts, making the mining of them a complex, time consuming, and expensive process. They are also a necessary component of a huge range of products, including many, many electronics. Many of the rare earth metal mines are located in China, and their near monopoly on the supply has created an artificial limitation on the supply of the metals to various companies.
The only one in North America is Molycorp, in California. Molycorp is quickly expanding as demand for these metals grows, the company also apparently has plans to begin mining tantalum, one of the so-called "conflict" minerals. Wiens points out that having a growing rare earth metals mining operation in the US will likely create a far more ethically sound situation for electronics manufacturers. Be sure to check out his full set of photographs of the mine.