There are 17 naturally occurring rare earth elements (REE): yttrium, scandium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Although not very familiar to most people, these elements are used by us all every day. By 2015, world demand for rare earth minerals is expected to reach 210,000 tons per year up from 136,100 tons in 2010. Currently, China provides most of our supply.
The National Mining Association has produced an info-graphic showing the major uses of the rare earth elements:
Despite the name “rare earths” the more common REE are each similar in crustal abundance to commonplace metals such as chromium, nickel, copper, zinc, molybdenum, tin, tungsten, and lead, but REEs rarely occur in economic concentrations, and that’s the problem.
The U.S. used to be self-sufficient in REE mined from one deposit, Mountain Pass in the Mojave desert, California, just west of Las Vegas, Nevada. That mine, a carbonatite intrusion with extraordinary contents of light REE (8 to 12% rare earth oxides) was discovered in 1949 and began production in 1952. Mining ceased in 2002 due to low prices and some environmental regulatory trouble triggered by a tailings spill. However, the mine was reactivated in 2012. Some other U.S. rare earth resources are shown on the map below.