Rare-Earth elementsRare Earth elements in U.S. not so rare: report

Approximately 13 million metric tons of rare Earth elements (“rare earths”) exist within known deposits in the United States, according to the first-ever nationwide estimate of these elements by the U.S. Geological Survey.

This estimate of domestic rare earth deposits is part of a larger report that includes a review of global sources for rare earths, information on known deposits that might provide domestic sources of rare earths in the future, and geologic information crucial for studies of the availability of rare earths to U.S. industry.

The report describes significant deposits of rare earths in fourteen states, with the largest known rare earths deposits at Mountain Pass, California; Bokan Mountain, Alaska; and the Bear Lodge Mountains, Wyoming. The Mountain Pass mine produced rare earths until it closed in 2002. Additional states with known rare earths deposits include Colorado, Florida, Georgia, Idaho, Illinois, Missouri, Nebraska, New Mexico, New York, North Carolina, and South Carolina.

“This is the first detailed assessment of rare earth elements for the entire nation, describing deposits throughout the United States,” commented USGS director Marcia McNutt, Ph.D. “It will be very important, both to policy-makers and industry, and it reinforces the value of our efforts to maintain accurate, independent information on our nation’s natural resources. Although many of these deposits have yet to be proven, at recent domestic consumption rates of about 10,000 metric tons annually, the U.S. deposits have the potential to meet our needs for years to come.”

Rare earths are a group of seventeen metallic elements with similar properties and structures that are essential in the manufacture of a diverse and expanding array of high-technology applications. Despite their name, they are relatively common within the Earth’s crust, but because of their geochemical properties, they are not often found in economically exploitable concentrations.

Hard-rock deposits yield the most economically exploitable concentrations of rare earths. USGS researchers also analyzed two other types of rare earths deposits: placer and phosphorite deposits. Placer deposits are alluvial formations of sandy sediments, which often contain concentrations of heavy, dense minerals, some containing rare earths. Phosphorite deposits, which mostly occur in the southeastern United States, contain large amounts of phosphate-bearing minerals. These phosphates can yield yttrium and lanthanum, which are also rare earths.

Ninety-six percent of rare earths produced globally now comes from China. New rare earths mines are being developed in Australia, and projects exploring the feasibility of economically developing additional rare earths deposits are under way in the United States, Australia, and Canada; successful completion of these projects could help meet increasing demand for rare earths, the report said.

Rare earths are important ingredients in high-strength magnets, metal alloys for batteries and light-weight structures, and phosphors. These are essential components for many current and emerging alternative energy technologies, such as electric vehicles, photo-voltaic cells, energy-efficient lighting, and wind power. Rare earths are also critical for a number of key defense applications.

This report is part of a larger, Department of Defense-funded study of how the United States, and the Department of Defense in particular, use rare earths, as well as the status and security of domestic and global supply chains. In addition, the USGS National Minerals Information Center maintains statistics on global mineral production, trade, and resources that include rare earth elements.

—Read more in Keith R. Long, Bradley S. Van Gosen, Nora K. Foley, and Daniel Cordier, “The Principal Rare Earth Elements Deposits of the United States—A Summary of Domestic Deposits and a Global Perspective” (USGS, 2010)