Deep below the surface of the Earth, in a Montana mine that once yielded gold, silver, lead and zinc, lies the next frontier of globally coveted minerals.
"So how valuable is this?" asked Scripps News Group's Global Affairs Correspondent Maya Rodriguez.
"Billions. It's worth billions," said Harvey Kaye, executive chairman of U.S. Critical Materials, a private rare-earth deposit and processing company that owns the Sheep Creek mine.
The company provided Scripps News Group with exclusive video showing deposits of rare earth elements.
"There's strong evidence to believe that below the surface there may lie a continuous source, which we would call the 'mother lode,'" Kaye said.
Rare earth elements — or rare earth minerals — are a series of 17 elements, found mainly at the bottom of the periodic table, with names such as lanthanum and promethium. They have unique magnetic and conductive properties used in everyday technology like smartphones and in medical machines such as MRIs.
"They're like the cinnamon and nutmeg of society," said Aaron Noble, head of Virginia Tech University's Department of Mining and Minerals Engineering.
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Noble uses a baking analogy to explain their value.
"The major components of the cake are the flour, and the eggs, and the milk. Really, in society, that's your aluminum, and your iron, and your crushed stone — things we produce a lot of in high volumes that we're very good at," Noble said. "The rare earth elements instead, like I said, are the cinnamon and nutmeg. They're not a big portion of the volume, but they are all the spice that brings out all the flavor."
Perhaps more importantly, though, rare earth elements are key to the nation's defense, and are used in systems from fighter jets to Virginia-class submarines to Tomahawk missiles.
"You can't build a missile, you can't build advanced radars — to give you an idea, the F-35 fighter has 920 pounds of rare earths in it. A submarine has more than 5,000 pounds of rare earth in it," Kaye said.
However, most of the rare earth supply is controlled by one country.
"China controls 85% of the rare earths in the world, and they control 95% of the processing ability," Kaye said.
That means the U.S. is dependent on China for the majority of its rare earth supply.
"If the Chinese are the source of rare earths, it creates a tremendous problem for our military," Kaye said.
Owning a deposit of rare earth elements is one thing. Mining, extracting and processing them is another — and notoriously difficult. Enter Dr. Robert Fox.
"We're problem solvers and we develop technological solutions to advanced problems," said Fox, who leads a research team at the Department of Energy's Idaho National Laboratory in Idaho Falls.
They are working to find ways to extract rare earths more sustainably.
"The key challenge that we face in this nation is bringing sustainable mining back to the United States and reinforcing sustainable mining practices — and that's going to take new technology," Fox said.
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Some of that technology involves extracting rare earth elements from discarded and recycled electronics.
"To reduce the amount that we need to demand from a mine, you develop recycled recovery techniques for e-waste," Fox said.
They are also finding rare earth minerals in more unusual waste, such as ash created from burning coal.
"What we are trying to do is get all the metals in here out," said Eugene Engmann, a researcher at the lab. "When you have a solid and liquid, it's easy to separate. And then we can have a solution which leaves your rare earth elements in there."
In another lab, researcher Chloe Tolbert is testing an electric field to separate rare earths.
"Rather than just being able to do a small batch scale separation, we're able to just run this constantly and be able to collect different fractions of rare earths," Tolbert said.
Some of the minerals used in the Idaho National Lab's experiments come from the Sheep Creek mine.
"The reason for that is we have the highest grade of rare earths ever discovered in America," Kaye said.
Still, it could take years to access that deposit because of U.S. mining regulations. On average, it takes 15 to 29 years to get a mine operating.
"We now are in a new position whereby we need to come together with a balance of understanding the geopolitical need to have rare earths," Kaye said.
"Do you see a future where the U.S. is 100% self-sufficient when it comes to rare earths?" Rodriguez asked.
"I see that future, but not for at least a period of time," Kaye responded.
Rare earth elements are so valuable that they have been part of U.S. trade talks with China. Beijing has used them as leverage in negotiations over tariffs imposed by the Trump administration earlier this year.
The U.S. has only one operational rare earth mining and processing facility, in Mountain Pass, California and China has a stake in that mine.
Realizing the risk to defense and national security, the Department of Defense announced last year it was awarding more than $400 million to establish a domestic rare earth supply chain.
President Trump also issued an executive order to create a fund guaranteeing purchases from U.S. companies producing rare earths. Officials are also discussing the possibility of creating a strategic stockpile of the minerals, similar to the nation's Strategic Petroleum Reserve.
