Mineralogy and Petrology

, Volume 110, Issue 6, pp 917–926 | Cite as

Bunnoite, a new hydrous manganese aluminosilicate from Kamo Mountain, Kochi prefecture, Japan

  • Daisuke Nishio-HamaneEmail author
  • Koichi Momma
  • Ritsuro Miyawaki
  • Tetsuo Minakawa
Original Paper


A new mineral, bunnoite, originating from Kamo Mountain in Ino, Kochi Prefecture, Japan, has been identified. Bunnoite occurs as veins and lenses in hematite-rich ferromanganese ore, is dull green in color, and forms foliated subhedral crystals up to 0.5 mm in length. Its hardness is 5½ on the Mohs scale and its calculated density is 3.63 g cm−3. The mineral is optically biaxial (+), with α = 1.709(1), β = 1.713(1), γ = 1.727(1) (white light), 2V meas = 54° and 2V calc = 57°. The empirical formula of bunnoite is (Mn2+ 5.36Mg0.27Fe2+ 0.25Fe3+ 0.11)Σ6.00(Al0.60Fe3+ 0.40)Σ1.00(Si5.89Al0.11)Σ6.00O18(OH)3, and its simplified ideal formula is written as Mn2+ 6AlSi6O18(OH)3. The mineral is triclinic P \( \overline{1} \), and the unit cell parameters refined from powder X-ray diffraction data are a = 7.521(5) Å, b = 10.008(8) Å, c = 12.048(2) Å, α = 70.46(5)°, β = 84.05(6)°, γ = 68.31(6)° and V = 793.9(9) Å3. The crystal structure of bunnoite has been solved by the charge flipping method in conjunction with single-crystal X-ray diffraction data and refined to R1 = 3.3 %. Bunnoite was found to have a layered structure with alternating tetrahedral and octahedral sheets parallel to the (\( \overline{1} \)11). The silicate tetrahedra form sorosilicate [Si6O18(OH)] clusters in the tetrahedral sheets, while the octahedra share edges to form continuous strips linked by [Mn2O8] dimers in the octahedral sheets. This mineral is classified as 9.BH according to the Nickel-Strunz system and has been named in honor of the Japanese mineralogist Michiaki Bunno (b. 1942).


Bunnoite New mineral Hydrous manganese aluminosilicate Ferro-manganese deposit Crystal structure Kochi prefecture 



The authors wish to thank Y. Tamura for acting as a guide at Kamo Mountain. The authors are also grateful to A. Kasatkin for providing a sample of akatoreite. Powder XRD and preliminary single-crystal XRD data were acquired at KEK (Proposal nos. 2013G540, 2014G173 and 2015G522). This work was supported by a Grant-in-Aid for Young Scientists B (Grant No. 15K17785) from the Japan Society for the Promotion of Science.

Supplementary material

710_2016_454_MOESM1_ESM.txt (62 kb)
ESM 1 (TXT 62 kb)


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Copyright information

© Springer-Verlag Wien 2016

Authors and Affiliations

  • Daisuke Nishio-Hamane
    • 1
    Email author
  • Koichi Momma
    • 2
  • Ritsuro Miyawaki
    • 2
  • Tetsuo Minakawa
    • 3
  1. 1.Institute for Solid State PhysicsThe University of TokyoChibaJapan
  2. 2.Department of Geology and PaleontologyNational Museum of Nature and ScienceTsukubaJapan
  3. 3.Department of Earth Science, Faculty of ScienceEhime UniversityMatsuyamaJapan

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