The first-ever nationwide estimate of rare earth elements by the U.S. Geological Survey determined 13 million metric tons of REE exist within known deposits in the United States.

USGS Director Marcia McNutt said, “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.”

The first detailed assessment of rare earths for the entire nation, the new USGS report is part of a larger study funded by the U.S. Department of Defense of how the U.S. and the DOD, in particular, use REE, as well as the status and security of domestic and global supply chains.

Currently, the U.S. imports all of its rare earth elements from foreign nations, principally China. The agency estimated that 126,230 metric tons of rare earth oxides were produced globally in 2009. Both the USGS and the European Union have ranked REE highest as mineral raw material of critical concern.

Estimated global reserves are 99 million metric tons with 36% of those reserves in China, 19% in the Commonwealth of Independent States, 13% in the U.S., 5% in Australia, 0.05% in Brazil, and 22% in other countries.

The USGS determined that significant REE deposits can be found in 14 U.S. states, with the largest known deposits located at Molycorp’s Mountain Pass California operation, Bokan Mountain in Alaska, and the Bear Lodge Mountains in Wyoming. Mountain Pass is the last REE deposit discovered and developed into a mine in the United States, which was more than five decades ago.

Additional states with known REE deposits include Colorado, Florida, Georgia, Idaho, Illinois, Missouri, Nebraska, New Mexico, New York, North Carolina and South Carolina.

In their survey, the USGS said hard-rock deposits “yield the most economically exploitable concentrations of REE.” The researchers also analyzed REE in placer and phosphorite deposits.”

“Long-term prospects for the discovery of new reserves and resources depend on sufficient exploration,” the USGS advised. The agency estimated that 150 projects exist globally that are prospecting and exploring for REE.

“Most of this activity began in the last 2 years and it will be some time before results are known,” the researchers noted. “Probability of discovery requires a quantitative mineral resource assessment, which has never been done for REE minerals in any country.”

“During the past 50 years outside of China, there has been little REE exploration and almost no mine development; hence, we have no real REE exploration and development record to draw upon for assessing the future pace of discovery and development,” the agency advised.

“The pipeline of new REE within the United States is rather thin, with 10 out of 150 REE exploration projects identified worldwide,” the researchers noted. “Unfortunately, the time required for development of new REE mines is on the order of at least a decade, perhaps much longer in the United States, and forecasting future supply that far into the future is hazardous.”

The study also determined the lack of mining industry exploration of REE deposits in the last few decades is paralleled by a low level of geological research.

To read the new USGS report: The Principal Rare Earth Elements Deposits of the United States-A summary of Domestic Deposits and a Global Perspective, go to http://pubs.usgs.gov/sir/2010/5220