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  • 1.
    Bergström, Jan
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Hou, Xian-Guang
    Yunnan University, Kunming.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Gut contents and feeding in the Cambrian arthropod Naraoia2007In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 129, p. 71-76Article in journal (Refereed)
  • 2.
    Biagioni, Cristian
    et al.
    Università di Pisa, Italy.
    Bosi, Ferdinando
    Sapienza Università di Roma, Italy.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Pasero, Marco
    Università di Pisa, Italy.
    The crystal structure of svabite, Ca5(AsO4)3F, an arsenate member of the apatite supergroup2016In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 101, p. 1750-1755Article in journal (Refereed)
    Abstract [en]

    The crystal structure of svabite, ideally Ca5(AsO4)3F, was studied using a specimen from the Jakobsberg mine, Värmland, Sweden, by means of single-crystal X‑ray diffraction data. The structure was refined to R1 = 0.032 on the basis of 928 unique reflections with Fo > 4s(Fo) in the P63/m space group, with unit-cell parameters a = 9.7268(5), c = 6.9820(4) Å, V = 572.07(5) Å3. The chemical composition of the sample, determined by electron-microprobe analysis, is (in wt%, average of 10 spot analyses): SO3 0.49, P2O5 0.21, V2O5 0.04, As2O5 51.21, SiO2 0.19, CaO 39.31, MnO 0.48, SrO 0.03, PbO 5.19, Na2O 0.13, F 2.12, Cl 0.08, H2Ocalc 0.33, O (≡ F+Cl) –0.91, total 98.90. On the basis of 13 anions per formula unit, the empirical formula corresponds to (Ca4.66Pb0.16Mn0.04Na0.03)Σ4.89(As2.96S0.04Si0.02P0.02)Σ3.04O12[F0.74(OH)0.24Cl0.01]. Svabite is topologically similar to the other members of the apatite supergroup: columns of face-sharing M1 polyhedra running along c are connected through TO4 tetrahedra with channels hosting M2 cations and X anions. The crystal structure of synthetic Ca5(AsO4)3F was previously reported as triclinic. On the contrary, the present refinement of the crystal structure of svabite shows no deviations from the hexagonal symmetry. An accurate knowledge of the atomic arrangement of this apatite-remediation mineral represents an improvement in our understanding of minerals able to sequester and stabilize heavy metals such as arsenic in polluted areas.

  • 3.
    Björling, Thomas
    et al.
    Stockholms universitet.
    Noréus, Dag
    Stockholms universitet.
    Jansson, Kjell
    Stockholms universitet.
    Andersson, Magnus
    Kungliga Tekniska Högskolan.
    Leonova, Ekaterina
    Stockholms universitet.
    Edén, Mattias
    Stockholms universitet.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Häussermann, Ulrich
    Stockholms universitet.
    SrAlSiH: A polyanionic semiconductor hydride2005In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 44, p. 7269-7273Article in journal (Refereed)
  • 4.
    Bosi, Ferdinando
    et al.
    Sapienza Università di Roma.
    Andreozzi, Giovanni B.
    Sapienza Università di Roma.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Zn-O tetrahedral bond length variations in normal spinel oxides2011In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 96, p. 594-598Article in journal (Refereed)
  • 5.
    Bosi, Ferdinando
    et al.
    Università di Roma, Italien.
    Andreozzi, Giovanni
    Università di Roma, Italien.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Experimental evidence for partial Fe2+ disorder at the Y and Z sites of tourmaline: a combined EMP, SREF, MS, IR and OAS study of schorl2015In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 79, no 3, p. 515-528Article in journal (Refereed)
  • 6.
    Bosi, Ferdinando
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Andreozzi, Giovanni B.
    Sapienza Università di Roma.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Lucchesi, Sergio
    Sapienza Università di Roma.
    Structural refinement of Mn-doped spinel: a case for tetrahedrally coordinated Mn3+ in an oxygen-based structure2007In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 92, p. 27-33Article in journal (Refereed)
  • 7.
    Bosi, Ferdinando
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    D'Ippolito, Veronica
    Sapienza Università di Roma.
    Andreozzi, Giovanni B.
    Sapienza Università di Roma.
    Blue spinel crystals in the MgAl2O4-CoAl2O4 series: II. Cation ordering over short range and long range scales2012In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 97, p. 1834-1840Article in journal (Refereed)
  • 8.
    Bosi, Ferdinando
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Crystal chemistry of the magnetite-ulvöspinel series2009In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 94, p. 181-189Article in journal (Refereed)
  • 9.
    Bosi, Ferdinando
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Crystal chemistry of the MgAl2O4-MgMn2O4-MnMn2O4 system: Analysis of structural distortion in spinel and hausmannite-type structures2010In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 95, p. 602-607Article in journal (Refereed)
  • 10.
    Bosi, Ferdinando
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Crystal chemistry of the ulvöspinel-qandilite series2014In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 99, p. 847-851Article in journal (Refereed)
  • 11.
    Bosi, Ferdinando
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Stoichiometry of synthetic ulvöspinel single crystals2008In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 93, p. 1312-1316Article in journal (Refereed)
  • 12.
    Bosi, Ferdinando
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Reznitskii, Leonid
    Russian Academy of Science.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Vanadio-oxy-chromium-dravite, NaV3(Cr4Mg2)(Si6O18)(BO3)3(OH)3O, a new mineral species of the tourmaline supergroup 2014In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 99, p. 1155-1162Article in journal (Refereed)
  • 13.
    Bosi, Ferdinando
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Reznitskii, Leonid
    Russian Academy of Science, Irkutsk.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Vanadio-oxy-dravite, NaV3(Al4Mg2)(Si6O18)(BO3)3(OH)3O, a new mineral species of the tourmaline supergroup2014In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 99, p. 218-224Article in journal (Refereed)
  • 14.
    Bosi, Ferdinando
    et al.
    Sapienza Università di Roma, Italy.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Fregola, Rosa Anna
    Università di Bari Aldo Moro, Italy.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Crystal chemistry of spinels in the system MgAl2O4-MgV2O4-Mg2VO42016In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 101, p. 580-586Article in journal (Refereed)
    Abstract [en]

    Eight spinel single-crystal samples belonging to the spinel sensu stricto-magnesiocoulsonite series (MgAl2O4-MgV2O4) were synthesized and crystal-chemically characterized by X‑ray diffraction, electron microprobe and optical absorption spectroscopy. Site populations show that the tetrahedrally coordinated site (T) is populated by Mg and minor Al for the spinel sensu stricto compositions, and only by Mg for the magnesiocoulsonite compositions, while the octahedrally coordinated site (M) is populated by Al, V3+, minor Mg, and very minor amounts of V4+. The latter occurs in appreciable amounts in the Al-free magnesium vanadate spinel, T(Mg)M(Mg0.26V3+1.48V4+0.26)O4, showing the presence of the inverse spinel VMg2O4. The studied samples are characterized by substitution of Al3+ for V3+ and (Mg2++V4+) for 2V3+ described in the system MgAl2O4-MgV2O4-VMg2O4.

    The present data in conjunction with data from the literature provide a basis for quantitative analyses of two solid-solution series MgAl2O4-MgV23+O4 and MgV23+O4-V4+Mg2O4. Unit-cell parameter increases with increasing V3+ along the series MgAl2O4-MgV2O4 (8.085–8.432 Å), but only slightly increases with increasing V3+ along the series VMg2O4-MgV2O4 (8.386–8.432 Å). Although a solid solution could be expected between the MgAl2O4 and VMg2O4 end-members, no evidence was found. Amounts of V4+ are nearly insignificant in all synthetic Al-bearing vanadate spinels, but are appreciable in Al-free vanadate spinel.

    An interesting observation of the present study is that despite the observed complete solid-solution along the MgAl2O4-MgV2O4 and MgV2O4-VMg2O4 series, the spinel structure seems to be unable to stabilize V4+ in any intermediate members on the MgAl2O4-Mg2VO4 join even at high oxygen fugacities. This behavior indicates that the accommodation of specific V-valences can be strongly influenced by crystal-structural constraints, and any evaluation of oxygen fugacities during mineral formation based exclusively on V cation valence distributions in spinel should be treated with caution. The present study underlines that the V valency distribution in spinels is not exclusively reflecting oxygen fugacities, but also depends on activities and solubilities of all chemical components in the crystallization environment.

  • 15.
    Bosi, Ferdinando
    et al.
    Sapienza Università di Roma, Rome, Italy.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Thermally induced cation redistribution in Fe‑bearing oxy‑dravite and potential geothermometric implications2016In: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 171, no 5, p. 1-14, article id 47Article in journal (Refereed)
    Abstract [en]

    Iron-bearing oxy-dravite was thermally treated in air and hydrogen atmosphere at 800 °C to study potential changes in Fe, Mg and Al ordering over the octahedrally coordinated Y and Z sites and to explore possible applications to intersite geothermometry based on tourmaline. Overall, the experimental data (structural refinement, Mössbauer, infrared and optical absorption spectroscopy) show that heating Fe-bearing tourmalines results in disordering of Fe over Y and Z balanced by ordering of Mg at Y, whereas Al does not change appreciably. The Fe disorder depends on temperature, but less on redox conditions. The degree of Fe3+–Fe2+ reduction is limited despite strongly reducing conditions, indicating that the fO2 conditions do not exclusively control the Fe oxidation state at the present experimental conditions. Untreated and treated samples have similar short- and long-range crystal structures, which are explained by stable Al-extended clusters around the O1 and O3 sites. In contrast to the stable Al clusters that preclude any temperature-dependent Mg–Al order– disorder, there occurs Mg diffusion linked to temperaturedependent exchange with Fe. Ferric iron mainly resides around O2− at O1 rather than (OH), but its intersite disorder induced by thermal treatment indicates that Fe redistribution is the driving force for Mg–Fe exchange and that its diffusion rates are significant at these temperatures. With increasing temperature, Fe progressively disorders over Y and Z, whereas Mg orders at Y according to the order–disorder reaction: YFe + ZMg → ZFe + YMg. The presented findings are important for interpretation of the post-crystallization history of both tourmaline and tourmaline host rocks and imply that successful tourmaline geothermometers may be developed by thermal calibration of the Mg– Fe order–disorder reaction, whereas any thermometers based on Mg–Al disorder will be insensitive and involve large uncertainties.

  • 16.
    Bosi, Ferdinando
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Reznitskii, Leonid
    Russian Academy of Science, Irkutsk.
    Crystallographic and spectroscopic characterization of Fe-bearing chromo-alumino-povondraite and its relationships with oxy-chromium-dravite and oxy-dravite2013In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 98, p. 1557-1564Article in journal (Refereed)
  • 17.
    Bruschini, Enrico
    et al.
    Sapienza Università di Roma.
    Speziale, Sergio
    Geoforschungszentrum, Potsdam.
    Andreozzi, Giovanni
    Sapienza Università di Roma.
    Bosi, Ferdinando
    Sapienza Università di Roma.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    The elasticity of MgAl2O4-MnAl2O4 spinels by Brillouin scattering and an empirical approach for bulk modulus prediction2015In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 100, p. 644-651Article in journal (Refereed)
  • 18. Deegan, F.M.
    et al.
    Whitehouse, Martin J.
    Swedish Museum of Natural History, Department of Geology.
    Troll, V.R.
    Budd, D.A.
    Harris, C.
    Geiger, H.
    Hålenius, U.
    Swedish Museum of Natural History, Department of Geology.
    Pyroxene standards for SIMS oxygen isotope analysis and their application to Merapi volcano, Sunda arc, Indonesia2016In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 447, p. 1-10Article in journal (Refereed)
    Abstract [en]

    Measurement of oxygen isotope ratios in common silicate minerals such as olivine, pyroxene, feldspar, garnet, and quartz is increasingly performed by Secondary Ion Mass Spectrometry (SIMS). However, certain mineral groups exhibit solid solution series, and the large compositional spectrum of these mineral phases will result in matrix effects during SIMS analysis. These matrix effects must be corrected through repeated analysis of compositionally similar standards to ensure accurate results. In order to widen the current applicability of SIMS to solid solution mineral groups in common igneous rocks, we performed SIMS homogeneity tests on new augite (NRM-AG-1) and enstatite (NRM-EN-2) reference materials sourced from Stromboli, Italy and Webster, North Carolina, respectively. Aliquots of the standard minerals were analysed by laser fluorination (LF) to establish their δ18O values. Repeated SIMS measurements were then performed on randomly oriented fragments of the same pyroxene crystals, which yielded a range in δ18O less than ± 0.42 and ± 0.58‰ (2σ) for NRM-AG-1 and NRM-EN-2, respectively. Homogeneity tests verified that NRM-AG-1 and NRM-EN-2 do not show any crystallographic orientation bias and that they are sufficiently homogeneous on the 20 μm scale to be used as routine mineral standards for SIMS δ18O analysis. We subsequently tested our new standard materials on recently erupted pyroxene crystals from Merapi volcano, Indonesia. The δ18O values for Merapi pyroxene obtained by SIMS (n = 204) agree within error with the LF-derived δ18O values for Merapi pyroxene but differ from bulk mineral and whole-rock data obtained by conventional fluorination. The bulk samples are offset to higher δ18O values as a result of incorporation of mineral and glass inclusions that in part reflects crustal contamination processes. The Merapi pyroxene SIMS data, in turn, display a frequency peak at 5.8‰, which allows us to estimate the δ18O value of the primary mafic magma at Merapi to ~ 6.1‰ when assuming closed system differentiation.

  • 19.
    Dekov, Vesselin
    et al.
    University of Sofia.
    Boycheva, Tanya
    University of Sofia.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Billström, Kjell
    Swedish Museum of Natural History, Department of Geology.
    Kamenov, George D.
    University of Florida.
    Shanks, Wayne C.
    U.S. Geological Survey, Denver.
    Stummeyer, Jens
    Bundesanstalt für Geowissenschaften, Hannover.
    Mineralogical and geochemical evidence for recent hydrothermal activity at the west wall of 12°50´N core complex (Mid-Atlantic Ridge): a new ultramafic-hosted seafloor hydrothermal deposit?2011In: Marine Geology, ISSN 0025-3227, E-ISSN 1872-6151, Vol. 288, p. 90-102Article in journal (Refereed)
  • 20.
    Dekov, Vesselin
    et al.
    University of Sofia.
    Boycheva, Tanya
    University of Sofia.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Petersen, Sven
    Leibiz-Institut für Meeresforschung, IFM-GEOMAR.
    Billström, Kjell
    Swedish Museum of Natural History, Department of Geology.
    Stummeyer, Jens
    Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover.
    Kamenov, George
    University of Florida.
    Shanks, Wayne
    U.S. Geological Survey, Denver.
    Atacamite and paratacamite from the ultramafic-hosted Logatchev seafloor vent field (14°45´ N, Mid-Atlantic Ridge)2011In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 286, p. 169-184Article in journal (Refereed)
  • 21.
    Dekov, Vesselin M.
    et al.
    University of Sofia.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Billström, Kjell
    Swedish Museum of Natural History, Department of Geology.
    Kamenov, George D.
    University of Florida.
    Munnik, Frans
    Forschungszentrum Dresden-Rossendorf.
    Eriksson, Lars
    Stockholms universitet.
    Dyer, Alan
    University of Salford.
    Schmidt, Mark
    Leibniz-Institut für Meeresforschung, IFM-GEOMAR.
    Botz, Reiner
    Universität Kiel.
    Native Sn-Pb droplets in a zeolitic amygdale (Isle of Mull, Inner Hebrides)2009In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 73, p. 2907-2919Article in journal (Refereed)
  • 22.
    Dekov, Vesselin M.
    et al.
    IFREMER.
    Rouxel, Olivier
    Woods Hole Oceanographic Institution.
    Asael, Dan
    IFREMER.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Munnik, Frans
    Helmoholz-Zentrum Dresden-Rossendorf.
    Native Cu from the oceanic crust: Isotopic insights into native metal origin2013In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 359, p. 136-149Article in journal (Refereed)
  • 23.
    D'Ippolito, Veronica
    et al.
    Sapienza Università di Roma.
    Andreozzi, Giovanni B.
    Sapienza Università di Roma.
    Bosi, Ferdinando
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Blue spinel crystals in the MgAl2O4-CoAl2O4 series: I. Flux growth and chemical characterisation2012In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 97, p. 1828-1833Article in journal (Refereed)
  • 24.
    D'Ippolito, Veronica
    et al.
    Sapienza Università di Roma.
    Andreozzi, Giovanni B.
    Sapienza Università di Roma.
    Bosi, Ferdinando
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Mantovani, L.
    Università di Parma.
    Bersani, D.
    Università di Parma.
    Fregola, Rosa Anna
    Università di Bari.
    Crystallographic and spectroscopic characterisation of a natural Zn-rich spinel approaching the endmember gahnite (ZnAl2O4) composition2013In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 77, p. 2941-2953Article in journal (Refereed)
  • 25.
    D'Ippolito, Veronica
    et al.
    Sapienza University, Rome, Italy.
    Andreozzi, Giovanni
    Sapienza University, Rome, Italy.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Hametner, Kathrin
    ETH, Zürich, Switzerland.
    Günther, Detlef
    ETH, Zürich, Swizerland.
    Color mechanisms in spinel: cobalt and iron interplay for the blue color2015In: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 42, no 6, p. 431-439Article in journal (Refereed)
    Abstract [en]

    Six natural, blue colored spinel crystals were studied chemically by electron microprobe and laser ablation inductively coupled plasma mass spectrometry (LAICP-MS) techniques and optically by UV–VIS–NIR–MIR spectroscopy in the range 30,000–2,000 cm1  to investigate the causes of their blue color hues. The positions of the absorption bands vary only marginally with the principal composition of the samples (gahnite vs. spinel s.s .). Although blue colors in spinels are frequently the result of various electronic processes in Fe cations, we demonstrate by comparison with synthetic Co-bearing samplesthat Co acts as an important chromophore also in natural spinels. Already at concentration levels of a few ppm (e.g.,>10 ppm), cobalt gives rise to absorption bands at ~18,000, 17,000 and 16,000 cm1  that result in distinct blue coloration. In spinels with insignificant Co contents, different shades of paler blue (from purplish to greenish blue) colors are caused by electronic transitions in TFe2+, MFe2+, MFe3and Fe2+–Fe3 cation pairs.

  • 26.
    Donadini, Fabio
    et al.
    ETH Zürich.
    Elming, Sten-Åke
    Luleå Tekniska Universitet.
    Tauxe, Lisa
    University of California, La Jolla.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Paleointensity determination on a 1.786 Ga old gabbro from Hoting, Central Sweden2011In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 309, p. 234-248Article in journal (Refereed)
  • 27.
    Esmaeilzadeh, Saeid
    et al.
    Stockholms universitet.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Valldor, Martin
    Technische Universität Braunschweig.
    Crystal growth, magnetic and optical properties of the ternary nitride MnSiN22006In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 18, p. 2713-2718Article in journal (Refereed)
  • 28.
    Fehr, Manuela A.
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Andersson, Per S.
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Gustafsson, Örjan
    Stockholms universitet.
    Mörth, Carl-Magnus
    Stockholms universitet.
    Iron enrichments and Fe isotopic compositions of surface sediments from the Gotland Deep, Baltic Sea2010In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 277, p. 310-322Article in journal (Refereed)
  • 29.
    Fehr, Manuela
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Andersson, Per S.
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Mörth, Carl-Magnus
    Stockholms universitet.
    Iron isotope variations in Holocene sediments of the Gotland deep, Baltic Sea2008In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 72, p. 807-826Article in journal (Refereed)
  • 30.
    Fregola, Rosa Anna
    et al.
    Università di Bari.
    Bosi, Ferdinando
    Swedish Museum of Natural History, Department of Geology.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Cation ordering over short range and long range scales in the MgAl2O4-CuAl2O4 series2012In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 97, p. 1821-1827Article in journal (Refereed)
  • 31.
    Fregola, Rosa Anna
    et al.
    University of Bari.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Bosi, Ferdinando
    Swedish Museum of Natural History, Department of Geology.
    D'Ippolito, Veronica
    Sapienza University of Rome.
    Andreozzi, Giovanni
    Sapienza University of Rome.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Optical absorption spectroscopy study of the causes for color variations in natural Fe-bearing gahnite: insights from iron valency and site distribution data.2014In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 99, p. 2187-2195Article in journal (Refereed)
  • 32.
    Gatta, Diego
    et al.
    University of Milan, Italy.
    Bosi, Ferdinando
    Sapienza Università, Rome, Italy.
    Fernandez Diaz, Maria Teresa
    Institut Laue-Langevin, Grenoble, France.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    H-bonding scheme in allactite: a combined single-crystal X-ray and neutron diffraction, optical absorption spectroscopy, FTIR and EPMA-WDS study2016In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 80, no 5, p. 719-732Article in journal (Refereed)
    Abstract [en]

    The crystal chemistry of allactite from Långban, Värmland (Sweden) was investigated by single-crystal X-ray and neutron diffraction, optical absorption spectroscopy, Fourier-transform infra-red spectroscopy (FTIR) and electron microprobe analysis by wavelength-dispersive spectroscopy (EPMA-WDS). The optical spectra indicate the presence of Mn in valence state 2+ only. Assuming 16 O atoms per formula unit, arsenic as As5+ and the (OH) content calculated by charge balance, the resulting formula based on the EPMA-WDS data is (Mn6.732+Ca0.13Mg0.12Zn0.02)Σ7.00(As5+)2.00O16H8, very close to the ideal composition Mn7(AsO4)2(OH)8. In the unpolarized FTIR spectrum of allactite, fundamental (OH)-stretching bands are observed at 3236, 3288, 3387, 3446, 3484, 3562 and 3570 cm–1, suggesting that a number of OH environments, with different hydrogen bond strengths, occur in the structure. The neutron structure refinement shows that four independent H sites occur in allactite with full site occupancy, all as members of hydroxyl groups. The complex hydrogen-bonding scheme in the allactite structure is now well defined, with at least nine hydrogen bonds energetically favourable with mono-, bi- and trifurcated configurations.

  • 33.
    Gatta, G.Diego
    et al.
    Università degli Studi de Milano.
    Bosi, Ferdinando
    Swedish Museum of Natural History, Department of Geology.
    McIntyre, Garry J.
    Australian Nuclear Science and Technology Organisation.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Static positional disorder in ulvöspinel: A single-crystal neutron diffraction study2014In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 99, p. 255-260Article in journal (Refereed)
  • 34.
    Grew, Edward S.
    et al.
    University of Maine.
    Barbier, Jacques
    McMaster University, Ontario.
    Britten, Jim F.
    McMaster University, Ontario.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Shearer, Charles K.
    University of New Mexico.
    The crystal chemistry of welshite, a non-centrosymmetric (P1) aenigmatite-sapphirine-surinamite group mineral2007In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 92, p. 80-90Article in journal (Refereed)
  • 35.
    Grew, Edward S.
    et al.
    University of Maine.
    Barbier, Jacques
    McMaster University, Ontario.
    Britten, Jim
    McMaster University, Ontario.
    Yates, Martin G.
    University of Maine.
    Polyakov, Vladislav O.
    Natural Science Museum of the Ilmen State Reserve.
    Shcherbakova, Elena P.
    Natural Science Museum of the Ilmen State Reserve.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Shearer, Charles K.
    University of New Mexico.
    Makarochkinite, Ca2Fe2+4Fe3+Ti4+Si4BeAlO20, a new beryllosilicate member of the aenigmatite-sapphirine-surinamite group from the Il’men Mountains (southern Urals), Russia2005In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 90, p. 1402-1412Article in journal (Refereed)
  • 36.
    Grew, Edward S.
    et al.
    University of Maine.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Pasero, Marco
    Università di Pisa.
    The crystal-chemistry of aenigmatite revisited: electron microprobe data, structure refinement, and Mössbauer spectroscopy of aenigmatite from Vesterøya (Norway)2008In: European journal of mineralogy, ISSN 0935-1221, E-ISSN 1617-4011, Vol. 20, p. 983-991Article in journal (Refereed)
  • 37.
    Grew, Edward S.
    et al.
    University of Maine.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Pasero, Marco
    Università di Pisa.
    Barbier, Jacques
    McMaster University, Ontario.
    Recommended nomenclature for the sapphirine and surinamite groups (sapphirine supergroup)2008In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 72, p. 839-876Article in journal (Refereed)
  • 38.
    Grew, Edward S.
    et al.
    University of Maine.
    Locock, Andrew J.
    University of Alberta.
    Mills, Stuart J.
    Museum Victoria.
    Galuskina, Irina O.
    University of Silesia.
    Galuskin, Evgeny V.
    University of Silesia.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Nomenclature of the garnet supergroup2013In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 98, p. 785-811Article in journal (Refereed)
  • 39.
    Hode Vuorinen, Jaana
    et al.
    Stockholms universitet.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Nb-, Zr- and LREE-rich titanite from the Alnö alkaline complex: Crystal chemistry and its importance as a petrogenetic indicator2005In: Lithos, ISSN 0024-4937, E-ISSN 1872-6143, Vol. 83, p. 128-142Article in journal (Refereed)
  • 40.
    Hode Vuorinen, Jaana
    et al.
    Stockholms universitet.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Whitehouse, Martin J.
    Swedish Museum of Natural History, Department of Geology.
    Mansfeld, Joakim
    Stockholms universitet.
    Skelton, Alasdair D. L.
    Stockholms universitet.
    Compositional variations (major and trace elements) of clinopyroxene and Ti-andradite from pyroxenite, ijolite and nepheline syenite, Alnö Island, Sweden2005In: Lithos, ISSN 0024-4937, E-ISSN 1872-6143, Vol. 81, p. 55-77Article in journal (Refereed)
  • 41.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Absorption of light by exchange coupled pairs of tetrahedrally coordinated divalent manganese in the helvite-genthelvite solid solution2011In: Periodico di Mineralogia, ISSN 0369-8963, Vol. 80, p. 105-111Article in journal (Refereed)
  • 42.
    Hålenius, Ulf
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Andreozzi, Giovanni B.
    Sapienza Università di Roma.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Structural relaxation around Cr3+ and the red-green color change in the spinel s.s.-magnesiochromite (MgAl2O4–MgCr2O4) and gahnite-zincochromite (ZnAl2O4–ZnCr2O4) solid solution series2010In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 95, p. 456-462Article in journal (Refereed)
  • 43.
    Hålenius, Ulf
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Bosi, Ferdinando
    Swedish Museum of Natural History, Department of Geology.
    Cation ordering in Pb2+-bearing, Mn3+-rich pargasite from Långban, Sweden2012In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 97, p. 1635-1640Article in journal (Refereed)
  • 44.
    Hålenius, Ulf
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Bosi, Ferdinando
    Swedish Museum of Natural History, Department of Geology.
    Color of Mn-bearing gahnite: A first example of electronic transitions in heterovalent exchange coupled IVMn2+-VIMn3+ pairs in minerals.2014In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 99, p. 261-266Article in journal (Refereed)
  • 45.
    Hålenius, Ulf
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Bosi, Ferdinando
    Sapienza Università di Roma, Rome, Italy.
    Gatedalite, Zr(Mn2+2Mn3+4)SiO12, a new mineral species of the braunite group from Långban, Sweden2015In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 79, no 3, p. 625-634Article in journal (Refereed)
    Abstract [en]

    Gatedalite, Zr(Mn2+2Mn3+4)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 MoKa X-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). Gatedalite is a member of the braunite group (general formula AB6SiO12). It is related to braunite (Mn2+Mn3+6SiO12) 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).

  • 46.
    Hålenius, Ulf
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Bosi, Ferdinando
    Swedish Museum of Natural History, Department of Geology.
    Oxyplumboroméite, Pb2Sb2O7, a new mineral species of the pyrochlore supergroup from Harstigen Mine, Värmland, Sweden2013In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 77, no 7, p. 2931-2939Article in journal (Refereed)
  • 47.
    Hålenius, Ulf
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Bosi, Ferdinando
    Swedish Museum of Natural History, Department of Geology.
    Gatedal, Kjell
    Nordmark Mining Museum.
    Crystal structure and chemistry of skarn-associated bismuthian vesuvianite2013In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 98, p. 566-573Article in journal (Refereed)
  • 48.
    Hålenius, Ulf
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Bosi, Ferdinando
    Swedish Museum of Natural History, Department of Geology.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    A first record of strong structural relaxation of TO4 tetrahedra in a spinel solid solution2011In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 96, p. 617-622Article in journal (Refereed)
  • 49.
    Hålenius, Ulf
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Bosi, Ferdinando
    Swedish Museum of Natural History, Department of Geology.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Galaxite, MnAl2O4, a spectroscopic standard for tetrahedrally coordinated Mn2+ in oxygen-based mineral structures2007In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 92, p. 1225-1231Article in journal (Refereed)
  • 50.
    Hålenius, Ulf
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Hatert, Frédéric
    Université de Liège, Belgium.
    Pasero, Marco
    Università di Pisa, Italy.
    Mills, Stuart
    Museum Victoria, Melbourne, Australia.
    IMA Commission in New Minerals, Nomenclature and Classification (CNMNC) Newsletter 272015In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 79, no 5, p. 1223-1230Article in journal (Other academic)
12 1 - 50 of 80
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