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  • 1.
    Andreozzi, Giovanni
    et al.
    Sapienza Università di Roma, Italy.
    D'Ippolito, Veronica
    Sapienza Università di Roma, Italy.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Bosi, Ferdinando
    Sapienza Università di Roma, Italy.
    Color mechanisms in spinel: a multi-analytical investigation of natural crystals with a wide range of coloration.2019In: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 46, no 4, p. 343-360Article in journal (Refereed)
  • 2.
    Bosi, Ferdinando
    University of Rome "La Sapienza".
    Balik-Zunic, Tonci
    Natural History Museum of Denmark.
    Thermal stability of extended clusters in dravite: a combined EMP, SREF and FTIR study.2016In: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 43, p. 395-407Article in journal (Refereed)
  • 3.
    Bosi, Ferdinando
    et al.
    Sapienza Università di Roma, 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 fluor-elbaite and Fe-bearing tourmalines2019In: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 46, no 4, p. 371-383Article in journal (Refereed)
  • 4.
    Bosi, Ferdinando
    et al.
    Sapienza Università di Roma, Italy.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Ciriotti, Marco
    Associazione Micromineralogica Italiana,Torino, Italy.
    Experimental cation redistribution in the tourmaline lucchesiite, CaFe2+3Al6(Si6O18)(BO3)3(OH)3O2018In: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 45, no 7, p. 621-632Article in journal (Refereed)
    Abstract [en]

    Natural Mg-rich lucchesiite was thermally treated in air and hydrogen atmosphere up to 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 intracrystalline geothermometry based on tourmaline. Overall, the experimental data (structural refinement, Mössbauer, infrared and optical absorption spectroscopy) show that thermal treatment of lucchesiite results in an increase of Fetot contents at Z balanced by an increase of Mg and Al at Y . This process is accompanied by a significant deprotonation of the O3 anion site. The Fe order–disorder reaction depends more on temperature, than on redox conditions. During heat treatment in H2 ,reduction of Fe3+ to Fe2+ was not observed despite strongly reducing conditions, indicating that the fO2  conditions do not exclusively control the Fe oxidation state at the present experimental conditions. On the basis of this and previous studies, the intersite order–disorder process induced by thermal treatment indicates that Fe redistribution is an important factor for Fe–Mg–Al-exchange and is significant at temperatures around 800 °C. As a result, Fe–Mg–Al intersite order–disorder is sensitive to temperature variations, whereas geothermometers based solely on Mg–Al order–disorder appear insensitive and involve large uncertainties. The presented findings are important for interpretation of the post-crystallization history of both tourmaline and tourmaline host rocks, and indicate that successful tourmaline geothermometers may be developed by thermal calibration of the Fe-Mg–Al order–disorder reaction.

  • 5.
    Bosi, Ferdinando
    et al.
    Sapienza Universita di Roma.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Lazor, Peter
    Uppsala Universitet.
    Reznitskii, Leonid
    Russian Academy of Sciences.
    Atomic arrangements around the O3 site in Al- and Cr-rich oxytourmalines: a combined EMP, SREF, FTIR and Raman study2015In: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 42, p. 441-453Article in journal (Refereed)
  • 6.
    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.

  • 7.
    Gori, Claudia
    et al.
    University of Parma, Italy.
    Tribaudino, Mario
    University of Parma, Italy.
    Mezzadri, Francesco
    University of Parma, Italy.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Co2+-doped diopside: crystal structure and optical properties2018In: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 45, no 5, p. 443-461Article in journal (Refereed)
    Abstract [en]

    Synthetic clinopyroxenes along the CaMgSi2O6– CaCoSi2O6 join were investigated by a combined chemical-structuralspectroscopic approach. Single crystals were synthesized by flux growth methods, both from Ca-saturated and Ca-deficient starting compositions. Single crystal structure refinements show that the incorporation of Co2+ at the octahedrally coordinated cation sites of diopside, increases the unit-cell as well as the M1 and the M2 polyhedral volumes. Spectroscopic investigations (UV–VIS–NIR) of the Ca-rich samples reveal three main optical absorption bands, i.e. 4T1g4T2g(F), 4T1g 4A2g(F) and 4T1g4T1g(P) as expected for Co2+ at a six-coordinated site. The bands arising from the 4T1g4T2g(F) and the 4T1g4T1g(P) electronic transitions, are each split into two components, due to the distortions of the M1 polyhedron from ideal Oh- symmetry. In spectra of both types, a band in the NIR range at ca 5000 cm−1 is caused by the 4A2g4T1g(F) electronic transition in Co2+ in a cubic field in the M2 site. Furthermore, an additional component to a band system at 14,000 cm−1, due to electronic transitions in Co2+ at the M2 site, is recorded in absorption spectra of Ca-deficient samples. No variations in Dq and Racah B parameters for Co2+ at the M1 site in response to compositional changes, were demonstrated, suggesting complete relaxation of the M1 polyhedron within the CaMgSi2O6– CaCoSi2O6 solid solution.

  • 8.
    Lenaz, Davide
    et al.
    University of Trieste.
    Henrik, Skogby
    Swedish Museum of Natural History, Department of Geology.
    Structural changes in the FeAl2O4- FeCr2O4 solid solution series and their consequences on natural Cr-bearing spinels.2013In: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 40, p. 587-595Article in journal (Refereed)
  • 9.
    Lenaz, Davide
    et al.
    Università degli Studi di Trieste.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Princivalle, Francesco
    Università degli Studi di Trieste.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    The MgCr2O4-MgFe2O4 solid solution series: Effects of octahedrally coordinated Fe3+ on T-O bond lengths2006In: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 33, p. 465-474Article in journal (Refereed)
  • 10.
    Nazzareni, Sabrina
    et al.
    Perugia University.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Crystal chemistry of Sc-bearing synthetic diopsides2013In: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 40, p. 789-798Article in journal (Refereed)
  • 11.
    Nyquist, Susanne
    et al.
    Stockholms universitet.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    An EELS study of near edge structures of the oxygen K-edge in spinels2014In: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 41, p. 255-265Article in journal (Refereed)
  • 12.
    Weis, Franz
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Ros, Linus
    Reichart, Patrick
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Kristiansson, Per
    Dollinger, Gunther
    Hydrogen concentration analysis in clinopyroxene using proton–proton scattering analysis2018In: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 45, p. 669-678Article in journal (Refereed)
  • 13.
    Weis, Franz
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Lazor, Peter
    Uppsala universitet.
    Hydrogen analysis in nominally anhydrous minerals by transmission Raman spectroscopy2018In: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 45, p. 597-607Article in journal (Refereed)
1 - 13 of 13
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