Hostname: page-component-cd9895bd7-fscjk Total loading time: 0 Render date: 2024-12-27T07:32:27.020Z Has data issue: false hasContentIssue false
  • English
  • Français

Gatedalite, Zr(Mn2+2Mn3+4)SiO12, a new mineral species of the braunite group from Långban, Sweden

Published online by Cambridge University Press:  02 January 2018

Ulf Hålenius  and
Ferdinando Bosi
Ulf Hålenius*
Affiliation:
Department of Geosciences, Swedish Museum of Natural History, Box 50007, SE-10405 Stockholm, Sweden
Ferdinando Bosi
Affiliation:
Department of Geosciences, Swedish Museum of Natural History, Box 50007, SE-10405 Stockholm, Sweden Dipartimento di Scienze della Terra, Sapienza Università di Roma, Piazzale Aldo Moro 5, I-00185 Rome, Italy CNR-IGG Istituto di Geoscienze e Georisorse, Sede di Roma, Piazzale Aldo Moro 5, I-00185 Rome, Italy
*
*E-mail: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

Gatedalite, Zr(Mn22+Mn43+)SiO12, is a new mineral of the braunite group. It is found in hausmannite-impregnated skarn together with jacobsite, Mn-bearing calcite, tephroite, Mn-bearing phlogopite, långbanite, pinakiolite and oxyplumboroméite at the Långban Mn-Fe oxide deposit, Värmland, central Sweden. The mineral occurs as very rare, small (≤60 μm), grey, submetallic, irregularly rounded anhedral grains. Gatedalite has a calculated density of 4.783 g/cm3. It is opaque and weakly anisotropic with reflectivity in air varying between 17.1 and 20.8% in the visible spectral range. Gatedalite is tetragonal, space group I41/acd, with the unit-cell parameters a = 9.4668(6) Å, c = 18.8701(14) Å, V = 1691.1(2) Å3 and Z = 8. The crystal structure was refined to an R1 index of 5.09% using 1339 unique reflections collected with MoKαX-ray radiation. The five strongest powder X-ray diffraction lines [d in Å, (I), (hkl)] are: 2.730(100)(224), 2.367(12)(040), 1.6735(12)(440), 1.6707(29)(048) and 1.4267(16)(264). Electron microprobe analyses in combination with single-crystal structure refinement resulted in the empirical formula: (Zr0.494+Mn0.402+Mg0.07Ca0.02Zn0.01Ce0.013+)Σ1.00(Mn4.443+Fe0.593+Mn0.572+Mg0.41Al0.01)Σ6.02Si0.99O12. Gatedalite is a member of the braunite group (general formula AB6SiO12). It is related to braunite (Mn2+Mn63+SiO12) through the net cation exchange (Zr4+ + Mn2+) → 2Mn3+, which results from the substitutions Zr4+ → Mn2+ at the 8-fold coordinated site (A in the general formula) coupled with a 2Mn2+ → 2Mn3+ substitution at the 6-fold coordinated sites (B in the general formula).

Keywords

gatedalitebraunite groupnew mineralelectron microprobecrystal-structure refinementreflection spectroscopyLångbanSweden
Type
Research Article
Information
Mineralogical Magazine , Volume 79 , Issue 3 , June 2015 , pp. 625 - 634
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2015

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.)

References

Andersson, U.B. (1997) The late Svecofennian, highgrade contact and regional metamorphism in southwestern Bergslagen (central southern Sweden). Geological Survey of Sweden, Research Report, 03-819/93. Uppsala, Sweden, pp. 29.Google Scholar
Armstrong, J.T. (1995) CITZAF: a package of correction programs for the quantitative electron microbeam X-ray analysis of thick polished materials, thin films, and particles. Microbeam Analysis, 4, 177–200.Google Scholar
Baudracco-Gritti, C., Caye, R., Permingeat, F. and Protas, J. (1982) La neltnérite, CaMn6SiO12, une nouvelle espece minerale du group de la braunite. Bulletin de Mineralogie, 105, 161–165.CrossRefGoogle Scholar
Boström, K., Rydell, H. and Joensuu, O. (1979) Långban-an exhalative sedimentary deposit? Economic Geology, 74, 1002–1011.Google Scholar
Brese, N.E. and O’Keeffe, M. (1991) Bond-valence parameters for solids. Acta Crystallographica, B47, 192–197.CrossRefGoogle Scholar
Brown, I.D. (2009) Recent developments in the methods and applications of the bond valence model. Chemical Reviews, 109, 6858–6919.CrossRefGoogle ScholarPubMed
Brown, I.D. and Shannon, R.D. (1973) Empirical bondstrength-bond-length curves for oxide. Acta Crystallographica, A29, 266–282.CrossRefGoogle Scholar
Christy, A. and Gatedal, K. (2005) Extremely Pb-rich rock-forming silicates including a beryllian scapolite and associated minerals in a skarn from Långban, Värmland, Sweden. Mineralogical Magazine, 69, 995–1018.CrossRefGoogle Scholar
Criddle, A.J. and Stanley, C.J. (1993) Quantitative Data File for Ore Minerals, third edition. Chapman & Hall, London. de Villiers, J.P.R. (1975) The crystal structure of braunite with reference to its solid solution behaviour. American Mineralogist, 60, 1098–1104.Google Scholar
de Villiers, J.P.R. (1980) The crystal structure of braunite II and its relation to bixbyite and braunite. American Mineralogist, 65, 756–765.Google Scholar
de Villiers, J.P.R., Dobson, S.M. and Buseck, P.R. (1991) Refinement of the crystal structure of neltnerite, a member of the bixbyite-braunite group of minerals. European Journal of Mineralogy, 3, 567–573.CrossRefGoogle Scholar
Flink, G. (1923) Über die Långbansgruben als Mineralvorkommen. Eine vorläufige Orientierung. Zeitschrift für Kristallographie, 58, 356–385.Google Scholar
Grew, E.S., Yates, M.G., Belakovskiy, D.I., Rouse, R.C., Su, S.-C. and Marquez, N. (1994) Hyalotekite from reedmergnerite-bearing peralkaline pegmatite, Dara-i-Pioz, Tajikistan and from Mn skarn, Långban, Värmland, Sweden: A new look at an old mineral. Mineralogical Magazine, 58, 285–297.CrossRefGoogle Scholar
Hålenius, U. and Bosi, F. (2012) Cation ordering in Pb2+-bearing, Mn3+-rich pargasite from Långban, Sweden. American Mineralogist, 97, 1635–1640.CrossRefGoogle Scholar
Hålenius, U., Bosi, F. and Gatedal, K. (2013) Crystal structure and chemistry of skarn-associated bismuthian vesuvianite. American Mineralogist, 98, 566–573.CrossRefGoogle Scholar
Holtstam, D. and Langhof, J. (editors) (1999) Långban, the Mines, their Minerals, History and Explorers. Raster Förlag, Stockholm, pp.215. Holtstam, D. and Mansfeld, J. (2001) Origin of a carbonate-hosted Fe-Mn-(Ba-As-Pb-Sb-W) deposit of Långban-type in central Sweden. Mineralium Deposita, 36, 641–657.CrossRefGoogle Scholar
Jonsson, E. (2004) Fissure-hosted mineral formation and metallogenesis in the Långban Fe-Mn-(Ba-As-Pb-Sb...) deposit, Sweden. Meddelanden frå n Stockholms Universitets Institution för Geologi och Geokemi, 318, pp. 110.Google Scholar
Magnusson, N.H. (1930) Långbans malmtrakt. Sveriges Geologiska Undersökning, Ca 23, 1–111.Google Scholar
Miletich, R., Allan, D.R. and Angel, R.J. (1998) Structural control of polyhedral compression in synthetic braunite, Mn2+Mn3+ 6 O8SiO4. Physics and Chemistry of Minerals, 25, 183–192.CrossRefGoogle Scholar
Moore, P.B. (1970) Mineralogy and chemistry of Långban-type deposits in Bergslagen, Sweden. Mineralogical Record, 1, 154–172.Google Scholar
Moore, P.B. and Araki, T. (1976) Braunite: its structure and relationship to bixbyite, and some insights on the genealogy of fluorite derivative structures. American Mineralogist, 61, 1226–1240.Google Scholar
Reinecke, T., Tillmanns, E. and Bernhardt, H.J. (1991) Abswurmbachite, Cu2+Mn3+ 6 [O8/SiO4], a new mineral of the braunite group: natural occurrence, synthesis, and crystal structure. Neues Jahrbuch für Mineralogie Abhandlungen, 163, 117–143.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.CrossRefGoogle Scholar
Sheldrick, G.M. (2013) SHELXL2013. University of Göttingen, Germany. Stephens, M.B., Ripa, M., Lundström, I., Persson, L., Bergman, T., Ahl, M., Wahlgren, C.-H., Persson, P.-O. and Wickström, L. (2009) Synthesis of the bedrock geology in the Bergslagen region, Fennoscandian Shield, south-central Sweden. Sveriges Geologiska Undersökning, Ba 58, 1–259.Google Scholar
Welin, E. (1992) Isotopic results of the Proterozoic crustal evolution of south-central Sweden; review and conclusions. Geologiska Föreningens i Stockholm Förhandlingar, 114, 299–312.CrossRefGoogle Scholar
Supplementary material: File

Hålenius and Bosi supplementary material

CIF

Download Hålenius and Bosi supplementary material(File)
File 17.9 KB