Constraints on F vs. OH incorporation in synthetic [6]Al-bearing monoclinic amphiboles

Ventura, Giancarlo Della; Robert, Jean-Louis; Sergent, José; Hawthorne, Frank C.; Delbove, F.

doi:10.1127/0935-1221/2001/0013/0841

Cited by 18 publications

(4 citation statements)

References 11 publications

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“…In other words, the alkali cation acts as a bridge by vibrationally connecting two facing O(3) anions (Fig. 1), and this feature is extremely important for the interpretation of the IR spectra of amphiboles with complex compositions (Della Ventura et al 2001Ventura et al , 2014. This effect has been verified in OH-F substituted richterites (e.g., Robert et al 1989Robert et al , 1999 and pargasite (Robert et al 2000), while Della have shown that the same is true for partially deprotonated amphiboles.…”

mentioning

confidence: 89%

Deprotonation of Fe-dominant amphiboles: Single-crystal HT-FTIR spectroscopic studies of synthetic potassic-ferro-richterite

Ventura

Susta

Bellatreccia

et al. 2017

American Mineralogist

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High-temperature Fourier transform infrared (HT-FTIR) spectroscopy was used to characterize the deprotonation process of synthetic potassic-ferro-richterite of composition A(K0.90Na0.07)B(Ca0.54Na1.46) c F e 4.22 2 + F e 0.78 3 + T S i 8 O 22 W O H 1.70 O 0.30 2 - ^\rmc\left( \rmFe-4.22^2 + \rmFe-0.78^3 + \right)^\rmT\rmS\rmi-8\rmO-22^\rmW\left( \rmO\rmH-1.70\rmO-0.30^2 - \right). Unpolarized single-crystal spectra were collected both in situ and on quenched samples, and heating experiments were conducted in air, at a rate of 10 °C/min. The room-T spectrum measured before annealing shows a main band at 3678 cm-1 and a minor band at 3622 cm-1; these are assigned to local configurations involving Fe2+ at M(1)M(1)M(3) and facing a filled and an empty alkali-site, respectively. At 400 °C, a new band grows at 3656 cm-1; this is the most intense feature in the pattern at 450 °C. At T ≥ 500 °C, all peaks decrease drastically in intensity, and finally disappear at T > 600 °C. The total absorbance measured in situ increases significantly in the 25 < T < 450 °C range, although the spectra collected on quenched samples show no OH loss in the same T range. This feature is consistent with an increase of the absorption coefficient (ϵ) with T, the reason for which is still unclear. However, this feature has significant implications for the quantitative use of FTIR data in HT experiments. Examination of the relevant OH-stretching bands shows that iron oxidation occurs preferentially at the M(1,3) sites associated with occupied A sites. The deprotonation temperature indicated by FTIR for single-crystals is around 100 °C higher that that obtained by HT-X-ray diffraction (XRD) on single crystal by Oberti et al. (2016), whereas that obtained by HT-XRD on powders is intermediate. This unexpected observation can be explained by considering that: (1) the iron oxidation process, which is coupled to deprotonation and is probed by XRD, occurs preferentially at the crystal surface where it is triggered by the availability of atmospheric oxygen; (2) the proton diffusion, probed by FTIR, is slower that the electron diffusion probed by XRD; thus, the temperature shift may be explained by a much longer escape path for H in single-crystals than in powders. These results suggest that possible effects due to crystals size should be carefully considered in HT experiments done on Fe-rich silicates

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confidence: 89%

Deprotonation of Fe-dominant amphiboles: Single-crystal HT-FTIR spectroscopic studies of synthetic potassic-ferro-richterite

Ventura

Susta

Bellatreccia

et al. 2017

American Mineralogist

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“…Because of this, available infrared spectroscopic data on pargasitic amphibole mainly involves studies on gem quality pargasites with simpler chemical composition (e.g., Heaveysege et al, 2015;Day et al, 2018), in addition to synthetic pargasite. FTIR spectra of experimentally synthesized pargasites are used to characterize the OH-F substitution (Robert et al, 2000;Della Ventura et al, 2001), and the change of absorption bands and configuration groups over the chemical transition to other compositions such as richterite (Della Ventura et al, 1999), tremolite (-cummingtonite) (Della Ventura et al, 2003;Jenkins et al, 2003;Ishida et al, 2008) and Cr-pargasite (Fialips-Guédon et al, 2000).…”

Section: Previous Ftir Studies On Pargasitic Amphibole and Amphibole ...mentioning

confidence: 99%

Formation of amphibole lamellae in mantle pyroxene by fluid-mediated metasomatism: A focal plane array FTIR study from the Carpathian-Pannonian region

Liptai,

Lange,

Patkó

et al. 2024

American Mineralogist

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Amphiboles in the upper mantle (most frequently pargasitic in composition) have recently gained attention due to their role in the water budget and potential control on the rheology and physical discontinuity layers of the mantle. Although nominally anhydrous minerals are often analyzed with Fourier-transform infrared (FTIR) spectroscopy, amphiboles, especially in natural samples, are only scarcely in the focus of such studies because of their complex structure and variable composition. In mantle xenoliths, amphibole occurs not only interstitially or forming veins, but also as lamellae within orthopyroxene and/or clinopyroxene This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America.The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

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“…(1996 a ) showed that SRO is common in amphiboles, and that bands in the infrared can be assigned to specific local clusters of ions that centre on the O(3) site (Hawthorne and Grundy, 1976). Extensive work since then (Hawthorne et al ., 1997, 2000; Della Ventura et al ., 1999, 2001, 2003; Robert et al , 1999, 2000; Hawthorne and Della Ventura, 2007; Leissner et al , 2015) has shown that both nearest-neighbour (NN) and next-nearest-neighbour (NNN) cations affect the principal OH-stretching frequency of the locally associated (OH) group, and both infrared and Raman spectroscopy of the principal OH-stretching region may be used as a sensitive probe of NN and NNN short-range arrangements in amphiboles.…”

Section: Short-range Order In the C2/m Amphibole Structurementioning

confidence: 99%

“…The chemical variability of natural amphiboles gives rise to many overlapping absorption bands in the principal OH-stretching region of the infrared spectrum, and the spectra commonly do not contain enough information to allow the spectra to be fit correctly. This problem may be overcome by using (1) synthetic amphiboles (Raudsepp et al ., 1987 a , b , 1991; Boschmann et al ., 1994; Della Ventura et al ., 1996 a , b , 1997, 1998 a , b , 1999, 2001, 2003; Hawthorne et al ., 1997, 2000; Robert et al ., 1999, 2000; Najorka and Gottschalk, 2003), the compositions of which are usually sufficiently constrained that a combination of Rietveld refinement or single-crystal refinement, infrared and MAS NMR spectroscopy, and local bond-valence arguments are sufficient to derive short-range order arrangements, or by using (2) gem amphiboles (Tait et al ., 2001; Abdu and Hawthorne, 2009; Heavysege et al ., 2015) for which the compositions are commonly simple. Thus the majority of work on SR-OD in amphiboles involves interpretation of the spectra of synthetic and gem-quality samples where the composition either can be controlled or is simple enough to result in spectra that can be interpreted rigorously.…”

Section: Introductionmentioning

confidence: 99%

Gem amphiboles from Mogok, Myanmar: crystal-structure refinement, infrared spectroscopy and short-range order–disorder in gem pargasite and fluoro-pargasite

Day

Hawthorne

Susta

et al. 2018

MinMag

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The crystal structures of six gem-quality pargasites and fluoro-pargasites from Mogok, Myanmar, space group C2/m, Z = 2, have been refined to R1 indices of 2.20–2.90% using MoKα X-radiation. The unit formulae were calculated from the results of electron-microprobe analysis, and were used with the refined site-scattering values and the observed mean bond lengths to assign site populations. TAl occurs at both the T(1) and T(2) sites but is strongly ordered at T(1). [6]Al is partly disordered over the M(2) and M(3) sites but does not occur at the M(1) site. ANa is split between the A(2) and A(m) sites and K occurs at the A(m) site. The infrared spectra in the principal OH-stretching region were measured and the fine structure was fit to component bands. The component bands were assigned to short-range ion arrangements over the configuration symbol M(1)M(1)M(3)–O(3)–A–O(3):T(1)T(1) using the refined site-populations and the expected frequencies from previously assigned spectra in more simple amphibole compositions, and correspond to the local arrangements: (1) MgMgMg–OH–Na–OH:SiAl; (2) MgMgMg–OH–Na–F:SiAl; (3) MgMgAl–OH–Na–OH:SiAl and (4) MgMgAl–OH–Na–F:SiAl.

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Constraints on F vs. OH incorporation in synthetic [6]Al-bearing monoclinic amphiboles

Cited by 18 publications

References 11 publications

Deprotonation of Fe-dominant amphiboles: Single-crystal HT-FTIR spectroscopic studies of synthetic potassic-ferro-richterite

Deprotonation of Fe-dominant amphiboles: Single-crystal HT-FTIR spectroscopic studies of synthetic potassic-ferro-richterite

Formation of amphibole lamellae in mantle pyroxene by fluid-mediated metasomatism: A focal plane array FTIR study from the Carpathian-Pannonian region

Gem amphiboles from Mogok, Myanmar: crystal-structure refinement, infrared spectroscopy and short-range order–disorder in gem pargasite and fluoro-pargasite

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