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. This groundbreaking trial will take place from January 11 to February 14, 2026, utilizing the deep-sea drilling vessel "Chikyu" to operate at depths of approximately 6,000 meters below sea level.

This test is part of the Cabinet Office's Strategic Innovation Promotion Program (SIP) project "Building Maritime Security Platforms" and represents the first step toward industrializing Japan's domestic rare earth production, a historic undertaking that could reshape global supply chains.

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. Heavy rare earths such as neodymium, dysprosium, and terbium are particularly crucial for manufacturing high-performance magnets.

The seabed around Minamitorishima, Japan's easternmost island, contains massive deposits of "rare earth mud," sediments with exceptionally high concentrations of these critical minerals. The estimated reserves total approximately 16 million tons, making it the world's third-largest rare earth deposit.

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 rare earth mud will undergo separation and refining tests at land-based facilities to complete final verification for practical application.

Challenges and Timeline for Commercialization

Many hurdles remain before rare earth mud can be commercially exploited. These include perfecting mining technology for the extreme 6,000-meter environment, reducing costs, optimizing separation and refining processes, and most importantly, completing comprehensive environmental impact assessments.

Current projections suggest commercialization will begin in fiscal year 2028 or later. 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.

However, Minamitorishima's rare earth mud holds strategic significance for Japan as it lies within Japan's EEZ, allowing development without requiring permissions from other nations.

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.

A Japanese Challenge Watched by the World

The connection test beginning with the ship's departure on January 11, 2026, marks the first step in this journey. The world watches with great interest as Japan pursues this pioneering challenge, hoping it will achieve sustainable deep-sea resource development.

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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