On December 23, 2025, Japan's Agency for Marine-Earth Science and Technology (JAMSTEC) announced that it will conduct the world's first rare earth mud mining system connection test in the exclusive economic zone (EEZ) surrounding Minamitorishima Island. The trial was scheduled to run from January 11 to February 14, 2026, using the deep-sea drilling vessel "Chikyu" at depths of roughly 6,000 meters.

The test falls under the Cabinet Office's Strategic Innovation Promotion Program (SIP) project "Building Maritime Security Platforms." It is the first field validation on the road to industrializing domestic rare earth production.

What is Rare Earth Mud and Why Minamitorishima?

Rare earth elements (REEs) are a group of 17 metallic elements essential for modern technology, including smartphones, computers, electric vehicle motors, and wind turbines. High-performance magnets depend on neodymium, a light rare earth, together with heavy rare earths such as dysprosium and terbium.

The seabed around Minamitorishima, Japan's easternmost island, contains massive deposits of "rare earth mud," sediments with exceptionally high concentrations of these critical minerals. A 2018 study by Waseda University and the University of Tokyo put resources in a 2,500-square-kilometer area south of the island at over 16 million tons, equivalent to several centuries of global demand.

Interestingly, fish played a key role in creating these ultra-high-concentration deposits. Research led by the University of Tokyo reveals that during a global cooling period around 34.5 million years ago, enhanced ocean circulation created nutrient-rich waters where fish populations thrived. As fish died and their bones accumulated on the seafloor, they concentrated rare earth elements from seawater to unprecedented levels.

Innovative "Closed-Loop Circulation System" Prioritizes Environmental Protection

JAMSTEC's newly developed mining system employs a "closed-loop circulation method" that builds upon the "mud circulation system" used in offshore oil and gas drilling. This approach minimizes the leakage and dispersion of suspended particles generated during mining operations, significantly reducing environmental impact on the deep-sea ecosystem.

The system works by deploying mining equipment to the seafloor, where it breaks up the rare earth mud into a slurry that is then pumped to the surface through riser pipes. Simultaneously, environmental monitoring will be conducted both on the seabed and aboard the ship using international standards (ISO) issued by SIP to rigorously assess the ecological impact of mining activities.

Seafloor observation equipment including "Edokko-1 COEDO," environmental DNA auto-sampling devices, and hydrophones will be installed to collect marine environmental data around the clock during operations.

Breaking Free from China Dependency: A Matter of Economic Security

This project draws global attention primarily due to its implications for economic security. Currently, China controls approximately 60-70% of global rare earth production and a staggering 90% of refining and processing capacity.

During the 2010 Senkaku Islands dispute, China effectively restricted rare earth exports to Japan, severely impacting Japanese manufacturing. More recently, in April 2025, China strengthened export controls on seven rare earth elements in retaliation for U.S. tariff measures, forcing some Japanese and American automakers to temporarily halt production.

Japan still imports about 60% of its rare earths from China, with near-total dependence (close to 100%) on Chinese sources for critical heavy rare earths like dysprosium and terbium used in EV motors.

Successful development of Minamitorishima's rare earth mud would provide Japan with a stable domestic supply source, significantly strengthening its supply chain resilience.

Steps Toward Full-Scale Mining in 2027

The upcoming connection test aims to verify the operational integrity of the mining system by lowering connected equipment to the 6,000-meter seafloor and testing the penetration of mining machinery into the seabed. This phase focuses on system validation rather than large-scale rare earth extraction.

Building on successful lifting tests conducted in August 2022 from 2,470-meter depths, JAMSTEC will now tackle the much more challenging 6,000-meter depth environment.

Data and expertise gained from this connection test will inform the planned full-scale mining trial in February 2027, targeting approximately 350 tons of extraction per day. The recovered mud will undergo separation and refining tests at land-based facilities.

Update, July 2026: The connection test began when Chikyu left Shimizu on January 12, 2026. The excavator reached the seafloor at a pipe length of 5,569 meters on January 30, and continuous mud lifting was confirmed in the early hours of February 1. Roughly 50 tons were recovered from three rare earth layers over three days, and the vessel returned to Shimizu on February 15. SIP and JAMSTEC published the analysis on July 24: about 54% of the total rare earth content was middle and heavy rare earths, including yttrium, gadolinium, and dysprosium, with no significant levels of hazardous or radioactive substances detected. By element, yttrium was the largest single component at 29.9%. JAMSTEC says this was the first time anywhere that mud has been lifted continuously to a vessel from beneath the seafloor at a pipe length of 5,569 meters. In the February 2027 full-scale trial, the recovered mud will be dewatered on Minamitorishima, shipped to the mainland, and put through separation, refining and smelting process tests. A comprehensive assessment covering economic viability is due by March 2028.

Challenges and Timeline for Commercialization

Plenty of hurdles remain before commercial extraction. Mining technology has to be proven at 6,000 meters, costs brought down, separation and refining optimized, and environmental impact assessments completed.

Current projections suggest commercialization will begin in fiscal year 2028 or later. Dai-ichi Life Research Institute notes that refining accounts for most of the production cost in rare earth operations, which makes lifting the mud from the deep sea only one part of the economics. However, the project benefits from collaboration among research institutions including the National Institute of Advanced Industrial Science and Technology (AIST), Kyoto University, Kochi University, and the University of Tokyo, as well as private companies such as Toyo Engineering, JGC Corporation, Modec, and Toa Corporation, forming a robust public-private partnership accelerating technological development.

Notably, Minamitorishima's rare earth mud contains virtually no radioactive or hazardous materials, unlike terrestrial rare earth ores. This characteristic offers the potential for simplified and more cost-effective separation and refining processes.

International Deep-Sea Resource Development Competition

Deep-sea mineral resource development has captured global attention beyond Japan. Various countries are advancing plans to extract seabed resources rich in rare metals, including manganese nodules and cobalt-rich crusts in international waters of the Pacific Ocean.

Minamitorishima's rare earth mud sits inside Japan's own EEZ, so development requires no other country's permission. That is where its strategic weight lies.

JAMSTEC has already conducted two years of environmental impact baseline surveys following guidelines established by the International Seabed Authority (ISA). The agency has contributed collected data to UNESCO's international database OBIS, demonstrating commitment to transparent and responsible development.

Japan's Comprehensive Rare Earth Strategy

The Minamitorishima project forms one pillar of Japan's multifaceted rare earth strategy. To reduce Chinese dependency, Japan has pursued several complementary approaches:

  1. Diversifying Supply Sources: Investing in overseas rare earth companies like Australia's Lynas Corporation (through Sojitz and JOGMEC) and France's Caremag (through Iwatani Corporation and JOGMEC)
  2. Developing Alternative Technologies: Research into rare-earth-free magnets and magnets requiring significantly reduced quantities
  3. Promoting Recycling: Improving rare earth recovery from used electronics and appliances ("urban mining")
  4. Strengthening National Stockpiles: Expanding strategic rare earth reserves through JOGMEC
  5. Developing Domestic Resources: The Minamitorishima rare earth mud project

By combining these strategies, Japan has successfully reduced its Chinese dependency from approximately 90% in 2010 to around 60% today. The Minamitorishima project's success could drive even greater reductions.

What the 6,000-Meter Test Actually Proves

The engineering question, whether mud can be brought from that depth to the surface, has an answer. What remains open is whether the operation can pay for itself and how far its effect on the deep-sea environment can be contained. The comprehensive assessment due by March 2028 is where those answers will come from.

How does your country secure critical mineral resources? We'd love to hear about the approaches your nation takes to ensure stable supplies of strategic materials like rare earths.

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