Japan Confirms Rare Earths in Deep-Sea Mud, Eyeing Reduced Reliance on China

TOKYO - Japan has confirmed a high concentration of valuable rare earth elements in deep-sea mud recovered from the seabed near its easternmost island, marking a notable step in its long-running effort to reduce dependence on China for the critical minerals that power modern technology. The country’s Cabinet Office and the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) said analysis of about 50 tonnes of sediment, retrieved from a depth of roughly 6,000 metres off Minamitorishima, revealed significant quantities of rare earths — including the harder-to-source heavy elements.

What the mud contains

According to the analysis, yttrium was the most abundant rare earth, making up roughly 30 percent of the total, while neodymium — a key ingredient in the powerful magnets used in electric-vehicle motors — accounted for about 20 percent. Heavy rare earths such as dysprosium and gadolinium were also detected. Crucially, around 54 percent of the rare earths were medium and heavy elements, the categories that are scarcer, more valuable and most tightly controlled by China.

A world-first retrieval

The sediment was gathered earlier this year by the deep-sea drilling vessel Chikyu — whose name means “Earth” — which extracted it from close to 6,000 metres down, in what Japan described as a world first at that depth. Announcing the retrieval, Prime Minister Sanae Takaichi called it “a first step toward industrialization of domestically produced rare earth in Japan,” and said the country would work toward resilient supply chains to avoid overdependence on any single nation. The programme falls under Japan’s Strategic Innovation Promotion Program.

A potentially vast resource

The deposits around Minamitorishima — a tiny island in the Ogasawara chain about 1,950 kilometres southeast of Tokyo — were first identified by a University of Tokyo research team in the early 2010s. One 2012 estimate put the rare-earth-rich mud in the area at some 6.8 million tonnes, equivalent to well over two centuries of Japan’s domestic demand. The mud also carries an environmental advantage: it contains little thorium or uranium, and the rare earths can be separated by soaking the sediment in acid, a comparatively simple process.

The China dimension

The push comes as Japan and other economies confront China’s dominance of the rare earth supply chain. China accounts for the large majority of global rare earth production and an even larger share of refining capacity, and in the past two years it has tightened export controls on several heavy rare earths and related magnets — including measures affecting Japan and major Japanese companies. Rare earths are indispensable to electric vehicles, renewable-energy systems, semiconductors, consumer electronics and defence equipment. Japan has cut its procurement reliance on China from nearly 90 percent in 2010 to around 63 percent in 2024, aided by diversification to suppliers such as Vietnam and investment in Australian production — but a structural vulnerability remains, since most rare earths still pass through China for refining wherever they are mined.

Years from the seabed to industry

Officials were candid that a confirmed resource is not the same as a working supply. Deputy Chief Cabinet Secretary Masanao Ozaki said moving toward industrialisation will require demonstrating the entire chain — from mining through separation and refining — and proving it is economically viable. Japan has scheduled a full-scale recovery test for early 2027 and a feasibility assessment by March 2027, and has floated plans to build a processing facility on Minamitorishima. For now, the seabed find is a promising milestone in a project whose commercial payoff, if it comes, is still several years away.