Far from mainland Japan, there is a dense field of nodules on a seamount located approximately 300 km off the remote Minami-Torishima Island (Marcus Island). While the field has been known for years, a first resource estimate was made public this summer by the Nippon Foundation and the University of Tokyo.
The estimate is based on data from surveys in 2010 and 2016 and a recent survey conducted between late April and early June this year.
The researchers estimate that there are 234 million tons of ferromanganese nodules covering an area of approximately 100 square kilometers at a depth of about 5,000 meters. The amount of nickel and cobalt in the nodules may cover Japan’s consumption for 75 and 11 years of consumption, respectively, reports The Japan Times and other Japanese media outlets.
«The University of Tokyo has found a wonderful mineral vein in the EEZ of Japan, a resource-poor country. It is necessary to extract them as soon as possible to provide them for industry use», Nippon Foundation Chairman Yohei Sasakawa said.
Extraction may occur more rapidly than expected, potentially aiding in curbing the country’s dependence on imported metals from other countries. While the deposit is certainly large enough to be considered economic, the depths may prove to be a challenge with complex mining solutions leading to higher costs per unit of metal extracted.
According to recent news stories, the team has revealed plans to start trial extraction by the end of May 2026 at rates of 2,500 tons per day.
While polymetallic nodules are found at various locations around the world, the three of potentially highest economic importance are the Clarion-Clipperton Zone (CCZ), the Peru Basin, and the north Indian Ocean. The CCZ is regarded as the biggest and is also the nodule field with the most exploration and knowledge-gathering activities.
In their 2016 research paper, the Japanese scientists remarked that even though Japan holds exploration licenses in the CCZ, they consider the location’s remoteness an obstacle to mining operations.
The Marcus Island nodule field is situated within Japan’s Exclusive Economic Zone. The nodule field is located on a seamount about 400 meters above the seafloor and has a northwest-trending ridge. The scientists note that the seafloor has an extremely strong acoustic reflectivity, a feature that may aid future exploration. The reflectivity is caused by the hard, dense nodules, lying on the seabed.
Geochemical analysis has revealed that the Marcus Island nodules have higher concentrations of rare earth elements and yttrium (REY) than nodules from the CCZ and the Peru Basin, and are comparable to the REY-rich mud deposit previously discovered south of Marcus Island. Japan is also working towards potentially developing this deposit.
The most promising area and the uppermost layer are estimated to yield 1.2 million tons of REE oxides. This amount is enough to account for the global demand for certain metals for decades.
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