南鳥島周辺海底に鉱物資源　レアメタル含有、大量分布―日本財団・東大

　日本財団と東京大は２１日、南鳥島（東京都小笠原村）周辺の排他的経済水域（ＥＥＺ）内で行った調査で、水深五千数百メートルの海底にニッケル、コバルトなどのレアメタルを豊富に含む海底鉱物資源「マンガンノジュール」（マンガン団塊）が大量にあるのを発見したと発表した。１００キロ四方の調査海域での総量は約２億３４００万トンと見積もられ、含まれるコバルトとニッケルは国内消費量のそれぞれ７５年分、１１年分に相当する。
　採取や精錬などのコストを踏まえても商業化可能な資源量だといい、日本財団などは早ければ来年度中に、１日２５００トン規模の採取実証を行う。
　マンガンノジュールは、石やサメの歯などを核に海水中の鉄やマンガンの酸化物が付着して成長した直径数～十数センチの球状の塊。マンガンや銅のほか、リチウムイオン電池などに不可欠なレアメタルを高濃度で含む。（2024/06/21-18:21）

More than 200 million tons of manganese nodules rich in rare metals exist on the seabed near Minamitorishima, a remote Tokyo island, the Nippon Foundation and the University of Tokyo said Friday.
   The nonprofit organization and the national university discovered a huge amount of the sea-bottom mineral concentrations that abundantly contain such rare metals as cobalt and nickel, both essential for lithium-ion batteries, in a survey that covered an area at depths of some 5,000 meters in the country's exclusive economic zone off the Pacific island.
   The research team, led by Yasuhiro Kato, professor at the university, estimates that there are 234 million tons of such nodules in the 100-square-kilometer survey area and that the amount of nickel in them is equivalent to 75 years of consumption in Japan and that of cobalt to 11 years.
   The volumes are believed to be enough for commercial use, including costs for extraction and refining. The organization plans to start extracting 2,500 tons of the mineral resource per day in an experimental project by the end of March 2026.
   The spherical nodules, which measure up to tens of centimeters in diameter, grow when iron and manganese oxides dissolved in seawater precipitate around their nuclei, such as stones and shark teeth. They also contain copper.