Japan is set to launch test mining of a unique deposit of rare earth element (REE)-rich deposits in an area off the Minami-Torishima Island (Marcus Island) in the Pacific Ocean, some 1,900 km southeast of Tokyo.
First identified by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) in 2013, this deposit could provide Japan with a stable, long-term supply of REEs to meet its industrial demands.
According to Reuters, the test mining will commence in January 2026. Pipes from a JAMSTEC deep-sea exploration vessel will extract the mud, which will be transported to the mainland for analysis to assess its metal content.
“The goal is to secure a domestic supply to enhance national security, rather than to enable private companies to profit from selling rare earths. This would mark the world’s first attempt to extract mud from the deep seabed for the separation and refining of rare earth elements”, said Shoichi Ishii, program director of the Cabinet Office’s national platform for innovative ocean developments, in an interview with the news agency earlier this year.
If the analysis yields positive results, the project aims to initiate trial operations in January 2027, using a system capable of extracting 350 t of mud per day.
While the concept is straightforward, the deposit lies at depths of 5,000-6,000 m, posing significant challenges for the pumps and pipes required for extraction.
Located within Japan’s exclusive economic zone (EEZ), the deposit’s potential justifies the effort.
A 2018 Nature Scientific Reports article reported core samples with REE and yttrium grades of up to 5,000 ppm (0.5 %), comparable to many global deposits.
Separation and selective processing could enhance the resource’s economic value by increasing the grade in the lifted mud. Constituting the coarser domain in the grain-size distribution, the authors of the 2018 paper report that using a hydrocyclone separator, they were able to selectively recover the biogenic calcium phosphate grains, which have high rare earth elements and yttrium content of up to 22,000 ppm.
The most promising area (102 km2) and the uppermost 10 m of the mud could yield 1.2 Mt of REE oxide, potentially meeting global demand for yttrium, europium, terbium, and dysprosium for decades. Across the entire study area, the supply could last centuries.
A 1990 research article noted that REE-rich muds in the Pacific, like those near Minami-Torishima, contain fish-bone debris composed of biogenic calcium phosphate, which accumulates REEs from seawater. Low sedimentation rates and high biolo-gical productivity have contributed to the formation of these deposits, making them a lesser-known fourth type of deep-sea mineral resource, alongside nodules, massive sulfides, and polymetallic crusts.
