Iron redox reactions in the tourmaline structure: High-temperature treatment of Fe3+-rich schorl

Filip, Jan; Bosi, Ferdinando; Novák, Milan; Skogby, Henrik; Tuček, Jiří; Čuda, J.; Wildner, Manfred

doi:10.1016/j.gca.2012.02.031

Cited by 59 publications

(33 citation statements)

References 52 publications

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“…This is in contrast to the results obtained on Fe-rich tourmaline by Filip et al (2012) who observed a change in the local (OH)-environments of schorl due to significantly progressive decrease of FTIR band related to the O1 site during heating in air (up to 900 °C). (2) T 0.00459(11) 0.00434(11) 0.00598(11) −0.00072(9) −0.00062(9) 0.00221(8) 0.00498 (7) O1 0.0124(5) 0.0124 (5) 0.0054 (7) 0.000 0.000 0.0062(2) 0.0101 (3) O2 0.0113(3) 0.0043(4) 0.0102 (5) As expected, the chemical compositions of the untreated and treated dravite samples are similar, with differences in some of the constituents very close to the analytical error (e.g.…”

Section: Infrared Spectroscopycontrasting

confidence: 99%

“…We also observe signs of minor H loss during heat treatment at 800 °C and above. In the previous studies, dehydration of Fe-containing tourmaline has been shown to follow, at least partially, the redox process (OH) -+ Fe 2+ ↔ O 2-+ Fe 3+ + ½ H 2 (Gonzalez-Carreño et al 1988;Filip et al 2012) with major loss of H at temperatures similar to those used in the present study. But, as the contents of Fe and other multivalent cations (e.g.…”

Section: Infrared Spectroscopysupporting

confidence: 66%

“…Hawthorne 1983;Gonzalez-Carreño et al 1988;Filip et al 2012). Table 8 Comparison of the band assignment models around the W (OH)-group at the O1 site of dravite a Average value from the range reported in Berryman et al (2015) b Unstable from a bond-valence perspective (e.g., Hawthorne 2002) …”

Section: Resultsmentioning

confidence: 99%

“…The currently published studies have mainly addressed the oxidation/reduction behavior of transition element cations such as Fe and Mn (e.g., Ertl and Rossman 2007;Filip et al 2012 and references therein; Taran et al 2015), or did not include crystal-structure information (e.g., Gonzalez-Carreño et al 1988). To date, no study has been focused on the high-temperature behavior of the short-range and long-range structure of Mg-Al-rich tourmalines such as dravite.…”

Section: Introductionmentioning

confidence: 99%

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Thermal stability of extended clusters in dravite: a combined EMP, SREF and FTIR study

2016

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Section: Infrared Spectroscopycontrasting

confidence: 99%

Section: Infrared Spectroscopysupporting

confidence: 66%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermal stability of extended clusters in dravite: a combined EMP, SREF and FTIR study

2016

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“…and Fe 3+ ions located in adjacent sites (e.g., Saegusa et al 1979;Kraczka and Pieczka 2001;Andreozzi et al 2008;Filip et al 2012). Therefore, we relate the fourth doublet of the black tourmaline spectrum to Fe 2+ -Fe 3+ IVCT.…”

Section: +mentioning

confidence: 99%

Chemical and spectroscopic characterization of tourmalines from the Mata Azul pegmatitic field, Central Brazil

Silva¹,

Moura²,

Queiroz³

et al. 2018

J. Geosci.

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This study characterizes natural black, blue, dark green, light green and pink tourmalines from granitic pegmatites of the Mata Azul Pegmatitic Field in central Brazil. The differences were assessed by applying electron-microprobe analysis as well as Mössbauer and optical spectroscopies. Mineral chemistry data show an increasing Mn/(Mn + Fe) atomic ratio as follows: black (0.01-0.02), blue (0.04-0.05), dark green (0.09-0.21), light green (0.33-0.42) and pink (0.68-1.00). The Mössbauer spectroscopy results show the presence of Fe 2+ (doublets with isomer shift (δ): 1.04-1.15 mm/s) for the black, blue, light green and dark green tourmalines. Fe 2+ is found in three different environments that are identified by quadrupole splitting (Δ) of 2.38-2.49 mm/s for the first, Δ = 2.13-2.34 mm/s for the second, and Δ = 1.54-1.71 mm/s for the third. The black sample spectrum has an additional fourth doublet (δ = 0.78 mm/s, Δ = 1.22 mm/s) that is assigned to an electron delocalization between Fe 2+ and Fe 3+. In the studied samples, the black color results most likely from high absorbance in all the visible spectra caused by Fe

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Short-range order in tourmaline: a vibrational spectroscopic approach to elbaite

2012

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Polarized Fourier-transform infrared and Raman spectra were acquired on an elbaite sample previously characterized by electron- and ion microprobe analysis, X-ray diffraction and structure refinement. Spectra from the two vibrational spectroscopy techniques reveal a close similarity in the OH-stretching region, with three main absorption bands strongly polarized in the c-axis direction. By means of bond-valence theory arguments, the observed OH bands are interpreted and assigned to specific local cation arrangements around the O1 (a W) and O3 ( V) anion sites. In combination with the relatively simple composition of the studied sample, bond-valence constraints are used to identify stable anion-cation arrangements, which permit the occurrence of short-range ordering to be assessed. Evidence for nearly complete short-range order at the O1 site, with the stable arrangements (Y)(LiAlAl)(0.6)-(W)(OH)(0.6) and (Y)(LiLiAl)(0.4)-(W)(F)(0.4), are presented. These two local arrangements can be further expanded to obtain the larger ordered clusters [(W)(OH)-(Y)(LiAl2)-(V)(OH)(3)-(Z)(Al)(6)](0.6) and [(W)(F)-(Y)(Li2Al)-(V)(OH)(3)-(Z)(Al)(6)](0.4)

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Iron redox reactions in the tourmaline structure: High-temperature treatment of Fe3+-rich schorl

Cited by 59 publications

References 52 publications

Thermal stability of extended clusters in dravite: a combined EMP, SREF and FTIR study

Thermal stability of extended clusters in dravite: a combined EMP, SREF and FTIR study

Chemical and spectroscopic characterization of tourmalines from the Mata Azul pegmatitic field, Central Brazil

Short-range order in tourmaline: a vibrational spectroscopic approach to elbaite

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