By Heather Somerville | Photography by Poppy Lynch for WSJ

Gabbro is an unremarkable rock, so cheap and abundant it is used for gravel and building roads. It may also be part of how America breaks its dependence on China's critical minerals.

On an industrial stretch on the west side of Oakland, Calif., a startup called Brimstone is processing gabbro with proprietary chemistry and off-the-shelf equipment to produce aluminum, magnesium and other minerals frequently imported from China.

Its lab, with a row of bikes parked inside the front door, hums quietly with workers in protective gear moving between beakers, kilns and mineral samples being tested for durability and composition. Bags of gabbro and similar calcium-bearing silicate rocks fill a shed out back and dot the office .

Brimstone's efforts, which haven't been previously reported, are part of a nationwide push to develop American sources of raw materials that the U.S. desperately needs and which China has long dominated. Startups from Silicon Valley to North Carolina and the U.K. are offering up new solutions to China's crackdown on critical mineral exports, propelled by record levels of private investment and advances in artificial intelligence.

Scientists who worked on self-driving cars in Silicon Valley are applying their mathematical formulas to critical-mineral discovery. Entrepreneurs are using AI applications to improve the success rates of mining exploration and create metal alloys that mimic the properties of critical minerals.

Any effort with a shot at success is focused on making the outputs cheaper to produce, softening China's edge.

"You need to make a process that is lower cost and higher profit, or you cannot bring production to the United States," said Brimstone Chief Executive Cody Finke.

Finke said his company's approach of using the same precursor rock, equipment and chemical process for a range of minerals yields costs that are 40% less than traditional methods. Once operating at full scale, its energy costs will be 30% to 50% cheaper, he said.

The U.S. has tried before to build out its own supply of critical minerals and the subset of them known as rare earths, but most efforts were quick to fizzle out as soon as China flooded the market with cheap supply, tanking prices. China dominates the high-risk and low-margin mining and processing of many of the minerals the U.S. depends upon to build everything from smartphones to cars, jets and satellites.

"If the U.S. is to make any progress here, it is going to have to rely on the innovation of startups," said Gracelin Baskaran, director of the Critical Minerals Security Program at the Center for Strategic and International Studies.

Beijing has clamped down on export restrictions of critical minerals since 2023, and a more onerous crackdown in April forced American manufacturers across industries to seek new suppliers, pause production and absorb higher costs. Even as Beijing eased some export controls in recent weeks, it is also tightening enforcement capabilities in anticipation of future restrictions.

"We can be sure China will be ready to weaponize these chokepoints again when politically advantageous," Reva Price, chair of the U.S.-China Economic and Security Review Commission, said in a recent report from the commission.

The U.S. relies on imports for most of the 54 minerals the country has designated as critical, according to the U.S. Geological Survey.

Experts agree that the U.S. is unlikely to ever return to the same level of dependency on China for these raw materials, now that businesses and policymakers have experienced how critical mineral supplies can affect industrial production, including of parts necessary for defense systems .

"I don't think there is anyone who is buying a serious quantity of critical minerals and rare earths who isn't considering resilience," said Willis Thomas, a critical minerals expert at CRU, a global commodities data firm. "A slightly larger cost for the critical minerals to ensure that you don't have to discuss it at the next board meeting is probably worth it."

Private investment and state capital are moving in tandem, benefiting traditional mining operations and startups across a supply chain that is just taking form. This year, venture capitalists have invested $600 million into U.S. critical-mineral startups, the highest level recorded, according to data provider PitchBook.

Under the Trump administration, the federal government has also invested hundreds of millions of dollars and taken stakes in rare-earths mining company MP Materials, rare-earth magnet startup Vulcan Elements, magnet recycling firm ReElement Technologies and lithium mining company Lithium Americas. It struck deals with more than a dozen countries, including Ukraine, Australia and the United Arab Emirates to secure access to critical mineral projects.

JPMorgan Chase in October announced a $1.5 trillion initiative that will include investments in critical minerals. A recently launched firm called Litore Partners, run by former Under Secretary for Nuclear Security Lisa Gordon-Hagerty, says it sources, finances and procures critical mineral supplies for governments and the private sector. Gordon-Hagerty, who declined to answer questions about the firm's funding and clients, said Litore was working with U.S. allies and partners to ensure their access to critical minerals.

"The question isn't whether it is feasible, the question is: Is it economic?" said Baskaran of the Center for Strategic and International Studies. "We all agree we need minerals. We need it to be economic."

This push into critical minerals is Brimstone's effort to reboot after finding itself on the wrong side of American politics. Founded in 2019, Brimstone started out making low-carbon cement, slashing emissions by more than half in a typically dirty industrial process by switching from limestone to carbon-free rocks, Finke said. The Trump administration earlier this year discarded the startup as a relic of the Biden-era focus on reducing carbon emissions, canceling a $189 million clean-energy award Brimstone received last year.

But Brimstone, which has raised more than $80 million from investors including Amazon and Bill Gates, had another play: refining methods to produce steel, magnesium, titanium, aluminum and alumina, aluminum's precursor, all from rocks like gabbro.

Aluminum is one of the most widely used industrial materials. The U.S. -- which doesn't have large reserves of bauxite, the rock traditionally used to make the metal -- produces less than 17% of the country's needs. Titanium is essential to the airline industry. Magnesium is used in components in aerospace, autos and other critical industries. China dominates the production of each.

"We are emphasizing the geopolitical risk part of our story. And that's because that's what resonates now," Finke said. Brimstone, which has minimal revenue, is appealing the award cancellation but is pragmatic about its prospects -- and choosing to hit the reset button on its relationship with the Trump administration.

Brimstone has much to prove: It has achieved mineral production only in a lab, or in the case of titanium, only on paper. It doesn't yet have a plant for industrial-scale production, nor a timeline for building one. Prior research shows that some forms of metals production from gabbro and similar rocks aren't commercially feasible -- they can be costly because of more complex and energy-intensive processes that produce a lot of waste.

Some experts are skeptical of startup efforts to solve what is more fundamentally a skilled labor shortage. "What we lack is real intelligence, which is generations of people we've lost who were capable of working with the real minerals," said Corby Anderson, an expert in mineral processing at the Colorado School of Mines.

Finke, 35, who dropped out of medical school to work on wastewater treatment technology for communities in Africa and India, is idealistic about the wider effects of Brimstone's cheaper materials. Homes and basic goods, the mainstays of the global economy, will be more affordable, he said.

"These are especially the things that the poorest people in the world need in order to be elevated out of poverty," Finke said.

Across the bay from Brimstone, at Stanford University, a collection of professors and students are using AI to help mining companies improve drilling outcomes. Jef Caers, who founded the group known as Mineral-X and previously worked on self-driving cars, said the same mathematical formulas used to program an autonomous vehicle are also guiding decisions for mining exploration.

Startup founder and Stanford alumnus John Mern is taking a similar approach with Terra AI, a startup using AI to help explorers determine when and where to drill by giving them better data on what's under the earth and how profitable it would be to drill. Around 98% of drilling projects end up as busts, industry data show, resulting in enormous unnecessary cost and environmental harm.

"Nobody can tell the good from the bad until you've already spent millions of dollars on the project," Mern said.

In the U.K., Milvus Advanced is using machine learning to create lab-engineered substitutes for critical minerals. Milvus founder Assia Kasdi said she buys metal salts, dissolves them in water and mixes them with other components that contain the desired property of a particular mineral, such as durability or conductivity. The process results in new alloys that can imitate platinum, silver and indium.

Similar efforts have been successful inside academia and U.S. national labs, but Milvus is a rare effort to commercialize the process. Kasdi said she can produce these new alloys at a cost that is at least 70% cheaper than the market price.

"This is the only way to compete with China," Kasdi said.

Write to Heather Somerville at heather.somerville@wsj.com

(END) Dow Jones Newswires

December 10, 2025 05:30 ET (10:30 GMT)

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