When the present decade began, the biggest rare earth mine in the world was operating in California.

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The mine was closed in 2002 amid environmental issues and low rare earth elements prices.

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From the 1960s until the 1980s, the Mountain Pass mine in California made the US the world leader in rare earth production, but it was later closed, largely due to competition with the elements imported from China.

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Resource Capital has not realized a penny from its investment in Molycorp, which aims to produce rare earth minerals (used in things like electric cars, wind turbines and iPods) at a previously shuttered mine in Mountain Pass, Calif.

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