The future of wind farms may well hinge on what happens to a 22.3-hectare hole in the ground at the edge of California's high desert.

The open-pit mine at Mountain Pass, California, holds the world's richest proven reserve of "rare earth" metals, a family of minerals vital to producing the powerful, lightweight magnets used in the engines of hybrid vehicles (mentioned in the above article) as well as generators in wind turbines.

Seeking to replace China as the leading supplier of these scarce materials, Colorado-based Molycorp Minerals LLC plans to reopen its long-idled quarry to resume extracting and refining thousands of tons of rare earth ore in the next few years.

Last month, Molycorp reached a joint venture deal with Arnold Magnetic Technologies Corp. of Rochester, New York, to make "permanent" magnets from rare metals at Mountain Pass.