Japan looks below the sea for rare earth supply

In February, deep-sea equipment removed reddish-brown mud from 6,000 m below the ocean surface near the island of Minamitorishima, about 2,000 km from the Japanese mainland. The test lifted approximately 50 metric tons (t) of mud, a milestone in the history of marine resource development and, for Japan, a major step toward developing a domestic supply of rare earth materials.

Since 2025, when China imposed rare earth export restrictions in response to US tariff measures, executives in industries ranging from electric vehicles to defense systems have learned how exposed they are to disruptions in their rare earth supply chains. But Japan had taken stock of its vulnerability back in 2010, when China restricted rare earth exports to the country in what is now known as the “rare earth shock.”

Since then, Japan has made diversification of rare earth sources a national priority. A government-sponsored initiative called the Japan Organization for Metals and Energy Security (Jogmec) is supporting companies investing in rare earths by providing risk capital and other assistance. Already, Japan’s dependence on China for rare earths has fallen from 90% just a few years ago to around 60% of its consumption.

Japan is now pursuing a three-track strategy to secure rare earths: develop a domestic supply system through the Minamitorishima project, build support for a local rare earth industry, and strengthen international partnerships to expand capacity abroad. Recent technological advances—such as compact mixer‑settler systems and new domestic refining facilities—are helping Japan address long‑standing weaknesses in its supply chain. Still, experts note that significant challenges remain, including scaling up refining, reducing costs, and assessing environmental impacts. Achieving true rare earth independence will be a long‑term endeavor.

A new frontier under the sea

Japan’s effort is not just about China, according to Takeshi Harada, deputy director general of Jogmec’s metal strategy department. “We are diversifying supply sources to reduce excessive dependence on any single country,” he says. “To ensure project execution, we support private companies not only in mining but also in materials and processing through equity finance and subsidy programs. We also use intergovernmental cooperation frameworks.”

In line with this approach, Jogmec is trying to strengthen Japan’s long-standing weakness in rare earth refining. It is partnering with domestic trading companies to participate in refining projects in Europe and supporting the development of new domestic refining capacity, including a recently announced rare earth plant—the first in 18 years.

Separately, the Minamitorishima project is a major national initiative led by the Cabinet Office. Participating in it are nine ministries and four national research institutes, including the Japan Agency for Marine-Earth Science and Technology.

Even prior to China’s rare earth restrictions, the Japan Agency for Marine-Earth Science and Technology had deployed the deep-sea drilling vessel Chikyū to collect and analyze geological samples. In 2018, researchers reported that large quantities of high-concentration rare earth mud were present within Japan’s exclusive economic zone around Minamitorishima.

A University of Tokyo research group estimated that reserves at the site are equivalent to several centuries of global demand. More recently, at a July 24 Cabinet Office briefing, Japanese officials disclosed that analysis of mud recovered during the February test show that 54% of its total rare earth content consists of medium and heavy rare earths such as yttrium, gadolinium, and dysprosium—materials in which China is particularly dominant.

In 2018, the Cabinet Office launched a strategy to move from research and exploration to actual development of a new supply chain. “For Japan, which experienced the rare earth shock, domestic production of rare earths and supply chain resilience are indispensable,” says Shoichi Ishii, program director of the office’s Cross-Ministerial Strategic Innovation Promotion Program.

Japan’s relationship with China was relatively stable back then, Ishii recalls, and supply chains were secure. “As a result, there was deep skepticism, technically and economically, about developing rare earth mud in ultradeep waters,” he says. “But I argued for the necessity of long-term R&D over a 10-year horizon and strategically advanced mud-lifting technology development in parallel with resource volume assessments.”

Commercial marine development for oil and gas typically extends to depths of no more than 3,000 m. At 6,000 m, water pressure is roughly 600 times what it is at the surface. Continuously lifting solid sediment from beneath the seafloor to a vessel under such extreme conditions far exceeded the conventional marine development norms of 2018.

Ishii, who previously worked at a major oil exploration company, notes that the key to resource assessment is accurately evaluating how far the layer containing rare earths extends beneath the seafloor. “For this reason, we gathered cutting-edge equipment from around the world and integrated it into a practical system,” he says.

For example, the group adopted the US-made autonomous underwater vehicle REMUS. “Marine robotics enabled visualization of resources, and we demonstrated for the first time globally that continuous mining is possible even for rare earth mud existing as solid material beneath the seafloor,” Ishii says.

The closed system for lifting sediment uses established oil industry technology to minimize pollution, Ishii says. “We adopted a closed circulation system based on proven technologies from global offshore oil development, minimizing leakage and dispersion of suspended matter into the deepsea environment,” he explains. Environmental monitoring conducted in parallel with the mining test uses seafloor-mounted probes, DNA samplers, and biological assays.

Still, some international researchers have raised concerns that deep‑sea exploration could harm marine ecosystems and the organisms that inhabit them.

In a paper, deep‑sea ecologist Diva Amon and colleagues note that many species in regions targeted for exploration remain undescribed, which makes it difficult to assess how mining disturbances might affect ecosystems or their recovery from disruption. They argue that baseline ecological data are still insufficient to evaluate whether deep‑seabed mining can proceed without causing serious harm.

But proponents point out that the mud from deep-sea mining offers two major environmental advantages over terrestrial ores: It lacks radioactive elements such as uranium and thorium and toxic contaminants like arsenic and cadmium. And because the rare earths are bound in calcium phosphate from ancient fish bones, they can be easily extracted with mild hydrochloric acid. In contrast, conventional rare earth ores must undergo high-temperature cracking, repeated roasting, and treatment with strong reagents such as concentrated sulfuric acid or sodium hydroxide to free the metals from silicate and carbonate minerals.

Finding rare earths overseas

As the Minamitorishima project advances as a long-term deep-sea initiative, Jogmec is focused on expanding and diversifying international land-based supplies spanning ore mining and the refining of rare earth mixtures into separate oxides. One example is a partnership with Australia’s Lynas Rare Earths. In 2011, Jogmec and the Japanese trading firm Sojitz established Japan Australia Rare Earths (JARE) and with Lynas began developing the Mount Weld mine in Western Australia; the parties signed an exclusive supply agreement for Japan.

JARE has continued financing Lynas via additional investment from Jogmec. In March 2023, Japan secured up to 65% of dysprosium and terbium production at Mount Weld for domestic supply; shipments of rare earth concentrate to Lynas’s refinery in Kuantan, Malaysia, began in October 2025. In March 2026, the supply agreement was renewed. It secured up to 75% of Lynas’s medium and heavy rare earth output for Japan with four more elements, including samarium, added.

Jogmec is also securing heavy rare earth resources in Africa. It has partnered with the Canadian firm Namibia Critical Metals, which is developing the Lofdal deposit in Namibia. The project, currently in the feasibility study stage, has mining rights through 2046. In March, the trading firm Toyota Tsusho acquired part of Jogmec’s 40% stake in the project.

Refining remains a bottleneck. In 2020, Japan’s Ministry of Economy, Trade, and Industry revised regulations to allow Jogmec to invest in rare earth refining. Jogmec and the Japanese conglomerate Iwatani subsequently invested in a plant that Caremag is building in southwestern France to reclaim rare earths from recycled magnets and ore.

The plant will extract rare earths from 2,000 t of recycled magnets and 5,000 t of ore annually. Iwatani signed a long-term supply agreement with Caremag that is expected to cover 20% of Japan’s future demand for dysprosium and terbium.

Within Japan, Shin-Etsu Chemical plans to build integrated refining facilities at its plant in Fukui Prefecture. The company established a 1,000 metric-ton-per-year rare earth oxide facility there in 2008, thus securing its position as one of Japan’s few integrated rare earth manufacturers. With a $109 million subsidy from Jogmec, Shin-Etsu will build new separation and refining plants for neodymium magnets.

Expanding domestic refining capacity poses several challenges. Rare earths share nearly identical chemical properties, and the conventional solvent extraction used to separate them requires hundreds of massive mixer-settler units connected in series. The set-up requires vast physical space and involves high costs for wastewater treatment.

To bypass this bottleneck, Emulsion Flow Technologies (EFT), a start-up founded in 2021 with technology from the Japan Atomic Energy Agency, has miniaturized conventional mixer-settlers to as little as one-fourth—and in some cases up to one-tenth—their normal size by dramatically increasing separation speed. The technology was originally developed for separation of spent nuclear fuel.

In conventional solvent extraction, water and organic phases are mixed into an emulsion, which allows target minerals to concentrate in one phase. Settling and separation follow. EFT’s technology lets mixing and oil-water separation occur simultaneously. The firm says this approach eliminates massive settler tanks, accelerates processing speeds, and leaves wastewater virtually oil-free.

“Settling is the most time-consuming step in solvent extraction,” says EFT CEO Hiroshi Suzuki. “Eliminating it dramatically increases separation speed.” Suzuki says he expects wide adoption in refining plants in Japan as well as overseas.

Japan is making steady progress toward developing an alternative rare earth supply chain. The next step in the deep-sea extraction process will be a full-scale demonstration test in February 2027 to verify stable mud-lifting efficiency at 350 t per day, followed by a comprehensive economic evaluation by March 2028. But Japan still has a long way to go to fully replace China’s important role as a supplier.

“Industrializing domestic rare earths requires overcoming four challenges: resource volume assessment, mining, refining and smelting, and transport infrastructure costs,” Ishii says. “Only the first two have been cleared so far.