Hostname: page-component-586b7cd67f-rcrh6 Total loading time: 0 Render date: 2024-11-24T03:56:27.324Z Has data issue: false hasContentIssue false
  • English
  • Français

Folvikite, Sb5+Mn3+(Mg,Mn2+)10O8(BO3)4, a new oxyborate mineral from the Kitteln mine, Nordmark ore district, Värmland, Sweden: description and crystal structure

Published online by Cambridge University Press:  28 February 2018

Mark A. Cooper ,
Gunnar Raade ,
Neil A. Ball ,
Yassir A. Abdu ,
Frank C. Hawthorne  and
Ralph Rowe
Mark A. Cooper
Affiliation:
Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba R3 T 2N2, Canada
Gunnar Raade
Affiliation:
Natural History Museum, University of Oslo, PO Box 1172 Blindern, NO–0318 Oslo, Norway
Neil A. Ball
Affiliation:
Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba R3 T 2N2, Canada
Yassir A. Abdu
Affiliation:
Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba R3 T 2N2, Canada
Frank C. Hawthorne*
Affiliation:
Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba R3 T 2N2, Canada
Ralph Rowe
Affiliation:
Canadian Museum of Nature, PO Box 3443 Stn D, Ottawa, Ontario K1P 6P4, Canada
*
*E-mail: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

Folvikite, Sb5+Mn3+(Mg,Mn2+)10O8(BO3)4, is a new oxyborate mineral from the Kitteln mine, Värmland, Sweden, where it occurs as a primary skarn mineral embedded in calcite. It forms striated prismatic crystals up to 0.3 mm, and is black to dark reddish-brown with submetallic lustre and a reddish-brown streak. It is brittle, has a Mohs hardness of 6, and the calculated density is 4.14 g/cm3. Folvikite is biaxial with indeterminate optic sign due to pervasive twinning. The optic axial angle is 68.9(4)°. Refractive indices were not measured; the calculated mean refractive index is 1.85. Strong pleochroism was observed in plane-polarized light: AB = brown (intermediate), OB = dark brown (maximum) and ON = honey brown (minimum). Folvikite is monoclinic, space group P2, a = 5.3767(10), b = 6.2108(10), c = 10.9389(18) Å, β = 94.399(9)°, V = 364.22(16) Å3 and Z = 1. Chemical analysis by electron microprobe gave Sb2O5 18.15, MgO 24.11, MnO 29.73, Mn2O3 11.62, Al2O3 0.27, Fe2O3 0.45, B2O3 15.27, sum 99.60 wt.%. The B2O3 content was assigned as B = 4 apfu and the Mn2O3 / (MnO + Mn2O3) ratio was determined from the crystal structure. The empirical formula was normalized on the basis of 20 anions pfu: (Sb5+1.02Mn3+1.34Al0.05Fe3+0.05Mg5.46Mn2+3.82□0.26)Σ12O8(BO3)4. A simplified formula may be written as Sb5+Mn3+(Mg,Mn2+)10O8(BO3)4 with Z = 1. The crystal structure was solved by direct methods and refined to an R1 index of 4.1%. Folvikite is a member of the (3 Å) zigzag wallpaper-borate structures in which chains of edge-sharing octahedra extend along the c axis and are cross-linked by BO3 groups. There are five X sites partly occupied by Mn2+ > Mg, one octahedrally coordinated M-site occupied by Sb5+ > Mg, two M sites occupied by Mg ≥ Mn > Sb5+, two M sites occupied by Mn3+ > Mn2+, two M sites occupied by Mg > Mn2+, and one M-site occupied by Mg > □; plus two [3]-coordinated B sites occupied by B. As with the other zigzag borates, the polyhedra are arranged in F-walls, C-walls and S-columns.

Keywords

folvikitenew mineralchemical analysiscrystal structureinfrared spectrumKitteln mineVärmlandSweden
Type
Article
Information
Mineralogical Magazine , Volume 82 , Issue 4 , August 2018 , pp. 821 - 836
Copyright
Copyright © Mineralogical Society of Great Britain and Ireland 2018 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

Associate Editor: Andrew Christy

References

Bartelmehs, K.L., Bloss, F.D., Downs, R.T. and Birch, J.B. (1992) Excalibr II. Zeitschrift für Kristallographie, 199, 186–196.Google Scholar
Brown, I.D. and Altermatt, D. (1985) Bond-valence parameters obtained from a systematic analysis of the inorganic crystal structure database. Acta Crystallographica, B41, 244–247.Google Scholar
Burns, P.C., Cooper, M.A. and Hawthorne, F.C. (1994) Jahn-Teller distorted Mn3+O6 octahedra in fredrikssonite, the fourth polymorph of Mg2Mn3+(BO3)O2. The Canadian Mineralogist, 32, 397–403.Google Scholar
Cooper, M.A. and Hawthorne, F.C. (1998) The crystal structure of blatterite, Sb5+3(Mn3+,Fe3+)9(Mn2+,Mg)35(BO3)16O32, and structural hierarchy in Mn3+-bearing zigzag borates. The Canadian Mineralogist, 36, 1171–1193.Google Scholar
Hansen, S., Hålenius, U. and Lindqvist, B. (1988) Antimony-rich pinakiolite from Långban, Sweden: a new structural variety. Neues Jahrbuch für Mineralogie Monatshefte, 231–239.Google Scholar
Hawthorne, F.C. and Grice, J.D. (1990) Crystal structure analysis as a chemical analytical method: application to light elements. The Canadian Mineralogist, 28, 693–702.Google Scholar
Hawthorne, F.C., Ungaretti, L. and Oberti, R. (1995) Site populations in minerals: terminology and presentation of results of crystal-structure refinement. The Canadian Mineralogist, 33, 907–911.Google Scholar
Holland, T.J.B. and Redfern, S.A.T. (1995) Unit cell refinement from powder diffraction data: the use of regression diagnostics. Mineralogical Magazine, 61, 65–77.Google Scholar
Magnusson, N.H. (1929) Nordmarks malmtrakt. Geologisk beskrivning. Sveriges Geologiska Undersökning, Serie Ca, 13, 98 pp.Google Scholar
Mills, S.J., Christy, A.G., Chen, E.C.C. and Raudsepp, M. (2009) Revised values of the bond valence parameters for [6] Sb (V)-O and [3-11] Sb (III)-O. Zeitschrift für Kristallographie, 224, 423–431.Google Scholar
Moore, P.B. and Araki, T. (1974) Pinakiolite, Mg2Mn3+O2[BO3]; warwickite, Mg(Mg0.5Ti0.5)O[BO3]; wightmanite, Mg5(O)(OH)5[BO3]·nH2O: crystal chemistry of complex 3 Å wallpaper structures. American Mineralogist, 59, 985–1004.Google Scholar
Norrestam, R. and Hansen, S. (1990) Structural investigation of an antimony-rich pinakiolite, Mg1.90Mn0.91Sb0.19O2BO3, from Långban, Sweden. Zeitschrift für Kristallographie, 191, 105–116.Google Scholar
Raade, G. and Folvik, H. (2013) On an unnamed Mg–Mn–Sb oxyborate from the blatterite locality of the Kitteln mine, Nordmark, Filipstad, Värmland, Sweden. Norsk Bergverksmuseum Skrift, 50, 49–54.Google Scholar
Raade, G., Mladeck, M.H., Din, V.K., Criddle, A.J. and Stanley, C.J. (1988) Blatterite, a new Sb-bearing Mn2+ – Mn3+ member of the pinakiolite group, from Nordmark, Sweden. Neues Jahrbuch für Mineralogie Monatshefte, 121–136.Google Scholar
Rowe, R. (2009) New statistical calibration approach for Bruker AXS D8 Discover microdiffractometer with Hi-Star detector using GADDS software. Powder Diffraction, 24, 263–271.Google Scholar
Shannon, R.D. (1976) Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Crystallographica, A32, 751–767.Google Scholar
Sjögren, A. (1876) Mineralogiska notiser. III. Manganosit och pyrochroit funna i Mossgrufvan Å Nordmarksfältet i Vermland. Geologiska Föreningens i Stockholm Förhandlingar, 3, 181–183.Google Scholar
Sjögren, A. (1878) Mineralogiska notiser. V. Manganförekomsten i Nordmarken. Geologiska Föreningens i Stockholm Förhandlingar, 4, 156–163.Google Scholar
Sjögren, A. (1887) Mineralogiska notiser. XIII. Om Nordmarks-periklasen. Geologiska Föreningens i Stockholm Förhandlingar, 9, 526–532.Google Scholar
Strunz, H. and Nickel, E.H. (2001) Strunz Mineralogical Tables. 9th Edition. E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart. 870 pp.Google Scholar
Supplementary material: File

Cooper et al. supplementary material

Cooper et al. supplementary material

Download Cooper et al. supplementary material(File)
File 53.6 KB