Hostname: page-component-cd9895bd7-q99xh Total loading time: 0 Render date: 2024-12-25T15:21:42.027Z Has data issue: false hasContentIssue false
  • English
  • Français

Jakobssonite, CaAlF5, a new mineral from fumaroles at the Eldfell and Hekla volcanoes, Iceland

Published online by Cambridge University Press:  05 July 2018

T. Balić-Žunić ,
A. Garavelli ,
D. Mitolo ,
P. Acquafredda  and
E. Leonardsen
T. Balić-Žunić*
Affiliation:
Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, DK-1350, Copenhagen K, Denmark
A. Garavelli
Affiliation:
Dipartimento di Scienze della Terra e Geoambientali, Universitá di Bari, via E. Orabona 4, I-70125 Bari, Italy
D. Mitolo
Affiliation:
Dipartimento di Scienze della Terra e Geoambientali, Universitá di Bari, via E. Orabona 4, I-70125 Bari, Italy
P. Acquafredda
Affiliation:
Dipartimento di Scienze della Terra e Geoambientali, Universitá di Bari, via E. Orabona 4, I-70125 Bari, Italy
E. Leonardsen
Affiliation:
St Karlsmindevej 46, DK-3390 Hundested, Denmark
*
E-mail: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

The new mineral jakobssonite, ideally CaAlF5, was first found in crusts collected in 1988 from a fumarole on the Eldfell volcano, Heimaey Island, Iceland. It was subsequently found in similar crusts collected in 1991 from a fumarole on the Hekla volcano, Iceland. It is associated with leonardsenite (IMA2011-059), ralstonite, heklaite, anhydrite, gypsum, jarosite, hematite, opal and several fluoride minerals that have not been fully characterized. Jakobssonite occurs as soft white fragile crusts of acicular crystals <50 μm long. Its calculated density is 2.89 g cm–3. Chemical analyses by energy-dispersive spectrometry on a scanning electron microscope produced a mean elemental composition as follows: Ca, 18.99; Al, 18.55; Mg, 1.33; Na, 0.33; F, 50.20; O, 10.39; total 99.79 wt.%. The empirical chemical formula, calculated on the basis of 7 atoms per formula unit with all of the oxygen as OH, is (Ca0.73Mg0.09Na0.02)Σ0.84Al1.06F4.09(OH)1.01. Jakobssonite is monoclinic, space group C2/c, with a = 8.601(1), b = 6.2903(6), c = 7.2190(7) Å, β = 114.61(1)o, V = 355.09(8) Å3and Z = 4. The crystal structure contains chains of [AlF6] octahedra which run parallel to the c axis. These chains are interconnected by chains of [CaF7] pentagonal bipyramids. Jakobssonite is isostructural with several other CaMIIIF5 compounds. The eight strongest lines in the powder diffraction diagram [d in Å (I) (hkl)] are as follows: 4.91 (18) (110), 3.92 (76) (200), 3.15 (68) (020), 3.13 (100) (1), 2.27 (22) (2), 1.957 (21) (400), 1.814 (20) (1), 1.805 (22) (20). The chemical and crystal-structure analyses of jakobssonite are similar to synthetic CaAlF5 with minor substitutions of light elements (e.g. Na) or vacancies for Ca, and OH for F.

Keywords

jakobssonitenew mineralfumarolessublimatesfluorideEldfellHeklaIceland
Type
Research Article
Information
Mineralogical Magazine , Volume 76 , Issue 3 , June 2012 , pp. 751 - 760
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2016

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

Acquafredda, P. and Paglionico, A. (2004) SEM-EDS microanalyses of microphenocrysts of Mediterranean obsidians: a preliminary approach to source discrimination. Europea. Journal of Mineralogy, 16, 419—429 CrossRefGoogle Scholar
Adamczyk, B., Troyanov, S.I., Schneider, M. and Kemnitz, E. (2000) Synthese, Kristallstruktur and thermischer Abbau von Fluoroaluminaten der Zusammensetzung (NH4)[M(H2O)6][AlF6] (M=Zn, Ni), [Zn(H2O)6][AlF5(H2O)] und (PyH)4 [Al2F10]·4H2O. Zeitschrift für Anorganische und Allgemein. Chemie, 626, 2543—2548 Google Scholar
Balić-Žunić, T. (2007) Use of three-dimensional parameters in the analysis of crystal structures under compression. Pp. 157-184 in: Pressure-Induced Phase Transitions 2007 (A. Grzechnik, editor). Transworld Research Network, Trivandrum, India..Google Scholar
Balić-Žunić, T., Garavelli, A., Acquafredda, P., Leonardsen, E. and Jakobsson, S.P. (2009) Eldfellite, NaFe(SO4)2, a new fumarolic mineral from Eldfell volcano, Iceland. Mineralogical Magazine, 73, 51—57 CrossRefGoogle Scholar
Balić-Žunić, T., Garavelli, A., Mitolo, D., Acquafredda, P. and Leonardsen, E. (2011) Jakobssonite, IMA 2011-036, CNMNC Newsletter No.10, October 2011, page 2556; Mineralogica. Magazine, 75, 2549—2561 Google Scholar
Body, M., Silly, G., Legein, C., Buzaré , J.-Y., Calvayrac, F. and Blaha, P. (2005) Structural investigations of b-CaAlF5 by coupling powder XRD, NMR, EPR and spectroscopic parameter calculations. Journal of Solid Stat. Chemistry, 178, 3655—3661 Google Scholar
Craig, D. and Brown, J. (1977) Phase equilibria in system CaF2-AlF3. Journal of the American Cerami. Society, 60, 396—398 Google Scholar
Domesle, R. and Hoppe, R. (1980) The crystal structure of Ca2AlF7. Zeitschrift fü. Kristallographie, 153, 317—328 Google Scholar
Dumora, D., Von der Mü hll, R. and Ravez, J. (1971) Structure crystalline de CaCrF5. Materials Researc. Bulletin, 6, 561—569 Google Scholar
Ferey, G., le Blanc, M. and Mercier, A.M. (1993) A new refinement of the crystal structure of MnAlF5: new structural correlations with MnCrF5 and Cr2F5 using orthogonal subcell twinning. Journal of Solid State Chemistry, 102, 9—19.CrossRefGoogle Scholar
Fourquet, J.L., Calage, Y. and Bentrup, U. (1994) FeAlF5: synthesis and crystal structure. Journal of Solid Stats Chemistry, 108, 189—192 CrossRefGoogle Scholar
Garavelli, A., Balić-Žunić, T., Mitolo, D., Acquafredda, P., Leonadsen, E. and Jakobsson, S.P. (2010) Heklaite, KNaSiF6, a new fumarolic mineral from Hekla volcano, Iceland. Mineralogica. Magazine, 74, 147—157 Google Scholar
Gudmundsson, A., Oskarsson, N., Grönvold, K., Saemundsson, K., Sigurdsson, O., Stefansson, R., Gislason, S.R., Einarsson, P., Brandsdottir, B., Larsen, G., Johannesson, H. and Thordarson, Th. (1992) The 1991 eruption of Hekla, Iceland. Bulletin of Volcanology, 54, 238—246 CrossRefGoogle Scholar
Graulich, J., Massa, W. and Babel, D. (2003) Zur Kristallstruktur von CaFeF5. Zeitschrift für anorganische und allgemein. Chemie, 629, 365—367 Google Scholar
Hemon, A. and Courbion, G. (1991) Refinement of a room-temperature structure of a-CaAlF5. Act Crystallographica, C47, 1302—1303 Google Scholar
Jakobsson, S.P., Leonardsen, E.S., Balić-Žunić, T. and Jonsson, S.S. (2008) Encrustations from three recent volcanic eruptions in Iceland: the 1963-1967 Surtsey, the 1973 Eldfell and the 1991 Hekla eruptions. Fjölrit Náttúrufraedistofnunar, 52, 65 pp.Google Scholar
Kun Wu, K. and Brown, I.D. (1973) Refinement of the crystal structure of CaCrF5. Materials Researc. Bulletin, 8, 593—598 Google Scholar
Mitolo, D., Garavelli, A., Balić-Žunić, T., Acquafredda, P. and Jakobsson, S.P. (2011) Leonardsenite, IMA 2011-059. CNMNC Newsletter No. 11, December 2011, page 2889; Mineralogical Magazine, 75, 2887—2893 Google Scholar
Ruste, J. (1979) X-ray spectrometry. Pp. 215 -267 in: Microanalysis and Scanning Electron Microscopy (F. Maurice, L. Meny and R. Tixier, editors). Summer School St-Martin-d’Hé res, France, September 11-16, 1978, Les Editions de Physique, Orsay, France..Google Scholar
Smith, D.G.W. and Nickel, E.H. (2007) A system of codification for unnamed minerals: report of the Subcommittee for Unnamed Minerals of the IMA Commission on New Minerals, Nomenclature and Classification. The Canadian Mineralogist, 45, 983—1055 CrossRefGoogle Scholar
Thorarinsson, S., Steinthorsson, S., Einarsson, T., Kristmannsdottir, H. and Oskarsson N. (1973) The Eruption on Heimaey, Iceland. Nature, 241, 372—375 CrossRefGoogle Scholar
Weil, M. and Werner, F. (2001) The thermal dehydration of magnesium aluminum pentafluoride dihydrate: crystal structures of MgAlF5(H2O)2 and MgAlF5. Monatshefte fü. Chemie, 132, 769—777 Google Scholar
Supplementary material: File

Balić-Žunić et al. supplementary material

Rietveld Analysis results

Download Balić-Žunić et al. supplementary material(File)
File 33.3 KB
Supplementary material: File

Balić-Žunić et al. supplementary material

Powder XRD data

Download Balić-Žunić et al. supplementary material(File)
File 57.6 KB