Abstract
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).
Similar content being viewed by others
References
Bayliss P (1983) Polytypes of pennantite. Can Mineral 21:545–547
Burns PC, Hawthorne FC (1993) Edge–sharing Mn2+O4 tetrahedra in the structure of akatoreite, Mn2+ 9Al2Si8O24(OH)8. Can Mineral 31:321–329
Fransolet AM (1978) Données nouvelles sur l'ottrélite d'Ottré, belgique. Bull Minéral 101:548–557
Fransolet A, Abraham K, Sahl K (1984) Davreuxite: a reinvestigation. Am Mineral 69:777–782
Lindemann W, Wogerbauer R, Berger P (1979) Die Kristallstruktur von Karpholith (Mn0.97Mg0.08FeII 0.07)(Al1.90FeIII 0.01)Si2O6(OH)4. Neues Jahrb Mineral Monatsh 1979: 282–287
Minakawa T (2000) Akatoreite from iron-manganese deposit of Kamo Mountain in Kurosegawa zone. Abstracts with Programs of Annual Meeting of the Mineralogical Society of Japan, the Mineralogical Society of Japan, P15, 107
Naumova IS, Pobedimskaya EA, Belov NV (1974) Crystal structure of carpholite MnAl2(Si2O6)(OH)4. Kristallografiya 19:1155–1160
Palatinus L, Chapuis G (2007) SUPERFLIP – a computer program for the solution of crystal structures by charge flipping in arbitrary dimensions. J Appl Crystallogr 40:786–790
Peacor DR, Essene EJ, Simmons WB, Bigelow WC (1974) Kellyite, a new Mn-Al member of the serpentine group from Bald Knob, North Carolina, and new data on grovesite. Am Mineral 59:1153–1156
Read PB, Reay A (1971) Akatoreite, a new manganese silicate from eastern Otago, New Zealand. Am Mineral 56:416–426
Sahl K, Jones PG, Sheldrick GM (1984) The crystal structure of davreuxite, MnAl6Si4O17(OH)2. Am Mineral 69:783–787
Seto Y, Nishio-Hamane D, Nagai T, Sata N (2010) Development of a software suite on X-ray diffraction experiments. Rev High Pressure Sci Technol 20:269–276
Shanon RD (1976) Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Cryst A32:751–767
Sheldrick GM (2008) A short history of SHELX. Acta Crystallogr A64:112–122
Smith WC, Bannister FA, Hey MH (1946) Pennantite, a new manganese-rich chlorite from Benallt mine, Rhiw, Carnarvonshire. Mineral Mag 27:217–220
Wakita K, Miyazaki K, Toshimitsu S, Yokoyama S, Nakagawa M (2006) Geology of the Ino district. Quadrangle Series, 1: 50,000, Geological Survey of Japan, AIST, 140 p
Acknowledgments
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.
Author information
Authors and Affiliations
Corresponding author
Additional information
Editorial handling: N. V. Chukanov
Electronic Supplementary Material
ESM 1
(TXT 62 kb)
Rights and permissions
About this article
Cite this article
Nishio-Hamane, D., Momma, K., Miyawaki, R. et al. Bunnoite, a new hydrous manganese aluminosilicate from Kamo Mountain, Kochi prefecture, Japan. Miner Petrol 110, 917–926 (2016). https://doi.org/10.1007/s00710-016-0454-2
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00710-016-0454-2