Discovery of extremely REY-rich mud in the western North Pacific Ocean

Koichi Iijima, Kazutaka Yasukawa, Koichiro Fujinaga, Kentaro Nakamura, Shiki Machida, Yutaro Takaya, Junichiro Ohta, Satoru Haraguchi, Yoshiro Nishio, Yoichi Usui, Tatsuo Nozaki, Toshitsugu Yamazaki, Yuji Ichiyama, Akira Ijiri, Fumio Inagaki, Hideaki Machiyama, Katsuhiko Suzuki, Yasuhiro Kato*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

57 Citations (Scopus)


We have discovered deep-sea mud that is extremely enriched in rare-earth elements and yttrium (together called REY) in the Japanese Exclusive Economic Zone around Minamitorishima Island, in the western North Pacific Ocean. The maximum total REY concentration reaches approximately 7000 ppm, which is much higher than that reported for conventional REY deposits on land and other known potential REY resources in the ocean. The extremely REY-rich mud is characterized by abundant phillipsite and biogenic calcium phosphate. In addition, the stratigraphic layer with the highest REY concentration occurs just -3 m beneath the seafloor. The shallow burial of these strata together with the high REY content, especially those of heavy rare-earth elements, suggest that the newly discovered extremely REY-rich mud may be a promising REY resource.

Original languageEnglish
Pages (from-to)557-573
Number of pages17
Issue number6
Publication statusPublished - 2016
Externally publishedYes


  • Deep-sea mineral resources
  • Extremely rey-rich mud
  • Minamitorishima island
  • Rare-earth elements
  • Western north pacific ocean

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology


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