Surveys conducted by a research group led by Japan Agency for Marine-Earth Science and Technology (JAMSTEC) Project Research Scientist Shiki Machida and others have revealed vast amounts of manganese nodules, which include rare metals and other resources, in the seafloor of the exclusive economic zone (EEZ) surrounding Marcus Island (Minami Torishima), one of the Ogasawara Islands. The finding was announced in Geochemical Journal.
In a seabed survey using the reflection of sound waves and a survey with manned research submersibles, the research team found a high concentration of manganese nodules in the seabed at a depth of 5,500 meters from the southern part to the eastern part of the EEZ. The area spans 44,000 square kilometers, which is larger than the Kyushu region, and each square meter has about 150 nodules. Each manganese nodule is about 5 centimeters in diameter and contains such rare earths as nickel and cobalt in addition to iron and manganese.
University of Tokyo professor Yasuhiro Kato, a member of the research group, said, “Extraction from the deep seafloor still presents the problem of cost, but I have high hopes for future technological innovation.”
The area also has “rare-earth mud,” and the manganese nodules have characteristics similar to those of “cobalt-rich crust.” Kato adds, “This discovery may offer hints for searching for other mineral resources.”