Rare earth minerals are scattered throughout the Earth's crust, but only in small quantities, making them hard to mine. However, rich deposits of these rare earth oxides are in China, giving it command of the market.
The U.S. has just one rare earth mining company, the Colorado-based Molycorp Inc. There are also working mines in Australia, and a proposed one in Malaysia.
Under the terms of the WTO complaint, China has 10 days to respond and must hold talks with the U.S., E.U. and Japan within 60 days. If an agreement cannot be reached within that time frame, the U.S. and its partners could request a formal WTO panel to investigate Chinese practices.
Associated Press writer Tom Raum contributed to this report.
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