Details
| Original language | English |
|---|---|
| Pages (from-to) | 549-559 |
| Number of pages | 11 |
| Journal | Schweizerische Mineralogische und Petrographische Mitteilungen |
| Volume | 82 |
| Issue number | 3 |
| Publication status | Published - 2002 |
Abstract
The results of infrared and Raman spectroscopic investigations in the OH-stretching and lattice-mode regions in synthetic ferrous-aluminous (OH,F)-biotites are presented. In the OH-stretching region (3800-3200 cm-1), all micas studied present a high intensity peak at high frequencies [3669 cm-1 for (OH)-annite and 3641 cm-1 for (OH)-Es] which can be decomposed into two bands and a low intensity peak at low frequencies [3535 cm-1 for (OH)-annite and 3589 cm-1 for (OH)-Es] which suggests rather a vacant octahedral site. Along the (OH,F)-annite join, the intense peak at 3669 cm-1 shifts to lower frequencies as XF increases from 0 to 0.4. In contrast, this peak shifts to higher frequencies along the (OH,F)-Es join (Es = K(Fe2.25Al0.75) (Si2.25Al1.75)O10(OH,F)2). The low-intensity V-band remains roughly unchanged. The two bands that compose the 3669 cm-1 peak are assigned to a N-band resulting from OH-Fe2+Fe2+Fe2+ (Tri-6+) vibrations and a Ib-band due to OH-Fe2+Fe2+Al3+ (Tri-7+) vibrations. As the amount of fluorine increases in micas of the (OH,F)-annite join, the N-band frequency varies weakly but its intensity decreases significantly, while the Ib-band becomes more intense. In contrast, these two bands show an opposite behaviour in (OH,F)-Es micas. The N-band intensity increases whereas that of the Ib-band decreases. The opposite evolution of the two main bands in the OH-stretching region shows that F is preferentially linked to Fe rather than to Al in (OH,F)-annite, whereas F is preferentially linked to Al rather than to Fe in (OH,F)-Es. Consequently, the bond strengths Al-F or Fe-F are not controlled by the Fe-F or Al-F avoidance rule (which would predict that fluorine is preferentially associated to Fe in all micas), but by structural constraints. The Al-F or Fe-F avoidance rule may not play a determining role on the fluorine content of the micas as it is generally agreed. The maximum fluorine contents in micas mainly depend on the ability of the dimensional adaptation of tetrahedral and octahedral layers.
Keywords
- Fe-F and Al-F avoidance rule, Fluorine, Infrared and raman spectroscopy, Trioctahedral ferrous micas
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geology
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
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In: Schweizerische Mineralogische und Petrographische Mitteilungen, Vol. 82, No. 3, 2002, p. 549-559.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - "Fe-F and Al-F avoidance rule" in ferrous-aluminous (OH,F) biotites
AU - Boukili, B.
AU - Holtz, Francois
AU - Bény, J. M.
AU - Robert, J. L.
N1 - Copyright: Copyright 2004 Elsevier Science B.V., Amsterdam. All rights reserved.
PY - 2002
Y1 - 2002
N2 - The results of infrared and Raman spectroscopic investigations in the OH-stretching and lattice-mode regions in synthetic ferrous-aluminous (OH,F)-biotites are presented. In the OH-stretching region (3800-3200 cm-1), all micas studied present a high intensity peak at high frequencies [3669 cm-1 for (OH)-annite and 3641 cm-1 for (OH)-Es] which can be decomposed into two bands and a low intensity peak at low frequencies [3535 cm-1 for (OH)-annite and 3589 cm-1 for (OH)-Es] which suggests rather a vacant octahedral site. Along the (OH,F)-annite join, the intense peak at 3669 cm-1 shifts to lower frequencies as XF increases from 0 to 0.4. In contrast, this peak shifts to higher frequencies along the (OH,F)-Es join (Es = K(Fe2.25Al0.75) (Si2.25Al1.75)O10(OH,F)2). The low-intensity V-band remains roughly unchanged. The two bands that compose the 3669 cm-1 peak are assigned to a N-band resulting from OH-Fe2+Fe2+Fe2+ (Tri-6+) vibrations and a Ib-band due to OH-Fe2+Fe2+Al3+ (Tri-7+) vibrations. As the amount of fluorine increases in micas of the (OH,F)-annite join, the N-band frequency varies weakly but its intensity decreases significantly, while the Ib-band becomes more intense. In contrast, these two bands show an opposite behaviour in (OH,F)-Es micas. The N-band intensity increases whereas that of the Ib-band decreases. The opposite evolution of the two main bands in the OH-stretching region shows that F is preferentially linked to Fe rather than to Al in (OH,F)-annite, whereas F is preferentially linked to Al rather than to Fe in (OH,F)-Es. Consequently, the bond strengths Al-F or Fe-F are not controlled by the Fe-F or Al-F avoidance rule (which would predict that fluorine is preferentially associated to Fe in all micas), but by structural constraints. The Al-F or Fe-F avoidance rule may not play a determining role on the fluorine content of the micas as it is generally agreed. The maximum fluorine contents in micas mainly depend on the ability of the dimensional adaptation of tetrahedral and octahedral layers.
AB - The results of infrared and Raman spectroscopic investigations in the OH-stretching and lattice-mode regions in synthetic ferrous-aluminous (OH,F)-biotites are presented. In the OH-stretching region (3800-3200 cm-1), all micas studied present a high intensity peak at high frequencies [3669 cm-1 for (OH)-annite and 3641 cm-1 for (OH)-Es] which can be decomposed into two bands and a low intensity peak at low frequencies [3535 cm-1 for (OH)-annite and 3589 cm-1 for (OH)-Es] which suggests rather a vacant octahedral site. Along the (OH,F)-annite join, the intense peak at 3669 cm-1 shifts to lower frequencies as XF increases from 0 to 0.4. In contrast, this peak shifts to higher frequencies along the (OH,F)-Es join (Es = K(Fe2.25Al0.75) (Si2.25Al1.75)O10(OH,F)2). The low-intensity V-band remains roughly unchanged. The two bands that compose the 3669 cm-1 peak are assigned to a N-band resulting from OH-Fe2+Fe2+Fe2+ (Tri-6+) vibrations and a Ib-band due to OH-Fe2+Fe2+Al3+ (Tri-7+) vibrations. As the amount of fluorine increases in micas of the (OH,F)-annite join, the N-band frequency varies weakly but its intensity decreases significantly, while the Ib-band becomes more intense. In contrast, these two bands show an opposite behaviour in (OH,F)-Es micas. The N-band intensity increases whereas that of the Ib-band decreases. The opposite evolution of the two main bands in the OH-stretching region shows that F is preferentially linked to Fe rather than to Al in (OH,F)-annite, whereas F is preferentially linked to Al rather than to Fe in (OH,F)-Es. Consequently, the bond strengths Al-F or Fe-F are not controlled by the Fe-F or Al-F avoidance rule (which would predict that fluorine is preferentially associated to Fe in all micas), but by structural constraints. The Al-F or Fe-F avoidance rule may not play a determining role on the fluorine content of the micas as it is generally agreed. The maximum fluorine contents in micas mainly depend on the ability of the dimensional adaptation of tetrahedral and octahedral layers.
KW - Fe-F and Al-F avoidance rule
KW - Fluorine
KW - Infrared and raman spectroscopy
KW - Trioctahedral ferrous micas
UR - http://www.scopus.com/inward/record.url?scp=0036917437&partnerID=8YFLogxK
M3 - Article
AN - SCOPUS:0036917437
VL - 82
SP - 549
EP - 559
JO - Schweizerische Mineralogische und Petrographische Mitteilungen
JF - Schweizerische Mineralogische und Petrographische Mitteilungen
SN - 0036-7699
IS - 3
ER -