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Vials in the Mountain Pass Mine’s lab hold ore and test samples of the rare-earth metals extracted from the rust-colored rock. The United States was once the top producer of such metals, but China now holds a near monopoly.

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A small floating pump works on removing groundwater that has accumulated in the pit of the mine.

enlarge Photos by Don Bartletti/Los Angeles Times

The pond that fills the bottom of the Mountain Pass rare-earth metal mine reflects the terraces. Digging at the mine in California’s Mojave Desert is expected to resume by the second half of 2011 after the water is pumped out. The mine holds metals that are indispensable in a variety of industrial and military uses, including new “green” technologies.

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Didymium oxide, used in electric motor magnets and cellphone speakers, is a product of the mine.

MOUNTAIN PASS, Calif. — Fear of a shortage of rare-earth metals used in high-tech military and industrial products has spawned global efforts to reopen abandoned mines, including the formidable Mountain Pass Mine in California's Mojave Desert.

Discovered in the 1940s by uranium prospectors, Mountain Pass contains an array of rare earths, including cerium and lanthanum, in concentrations almost double those found at the world's biggest rare-earth mine, China's Bayan Obo.

"You're looking at the greatest rare-earth deposit in the world," says operations manager John Benfield as he ushers a visitor around the 2,200-acre site 60 miles southwest of Las Vegas.

Benfield's employer, Molycorp Minerals in Colorado, has just begun a two-year effort to restore Mountain Pass to its former role as a leading global producer. Those plans were given a boost recently amid fears that China was poised to ban exports of some of the scarcer rare-earth metals and to sharply limit shipments of others.

Although the Chinese government has sought to allay those concerns, a possible ban served as a reminder that the Asian nation is nearly the sole source worldwide for rare-earth metals and is likely to remain so for at least the next two years.

"You always want multiple sources for your raw materials," said Jim Hedrick, commodity specialist with the U.S. Geological Survey. "There could be a natural disaster that significantly disrupts the supply, or there could be geopolitical issues."

The reopening of the mine and related processing facilities would create about 900 jobs at Mountain Pass – about 100 people work there now – and provide U.S. companies with a reliable source for many key rare-earth metals.

These minerals, such as samarium and neodymium, are prized for chemical properties that make them indispensable in a variety of industrial and military uses, including polishing glass, oil refining and manufacturing missile guidance systems.

They also play a crucial role in the development of "green" technologies such as hybrid cars, wind turbines and compact fluorescent lightbulbs. Heat-resistant magnets made with rare-earth alloys are key components of the electric motor in the Toyota Prius, for example.

Mining operations ceased at Mountain Pass in 2002 amid environmental concerns and cut-rate competition from China, although processing of previously dug ore continues.

On a recent Friday, as the weekend traffic flowed on Interstate 15 toward Las Vegas and the temperature hovered around 110 degrees Fahrenheit, the ore processing facilities hummed with activity. But the crushing mill and the conveyors that fed it with rock from the mine were silent.

The mine itself is about 1,500 feet across – impressive to the uninitiated but smallish compared with the mile-wide behemoths around the globe where copper, gold and other minerals are excavated.

There's no giant earth-moving equipment rumbling about. Most of it was sold off when the mine was shut down. A small pump floats on the surface of the brackish green water 300 feet below.

Molycorp hopes to generate big profit at Mountain Pass by building an integrated manufacturing chain that starts with raw ore and ends with finished products ready for market.

"We don't want to be just a supplier of basic materials to other industries," said Benfield, the operations chief. "We want to develop our own technologies so we can determine our own destiny rather than rely on others. We're not just a mine."

The United States was once the world leader in rare-earth metal production. But low-cost competition from China has given that nation a near monopoly on rare-earth exports. In addition, China is becoming a key producer of rare-earth magnets.

That worries some analysts who fret that China could dominate the market for next-generation clean-energy technology in much the same way a handful...