Intersite OH-F distribution in an Al-rich synthetic phlogopite

Papin, Arnaud; Sergent, José; Robert, Jean-Louis

doi:10.1127/ejm/9/3/0501

Cited by 34 publications

(24 citation statements)

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“…The proton H + points almost directly toward the interlayer cation and, consequently, has a negligible interaction with the tetrahedral basal O atoms. The effects of F --OH -substitution on the structure stability have attracted the attention of many researchers (Munoz 1984;Robert et al 1993;Papin et al 1997;Mason 1992;Boukili et al 2001;Fechtelkord et al 2003). The occurrences of F-rich natural micas are rare (Joswig 1972;Hazen and Burnham 1973;Russell and Guggenheim 1999) and several investigations concern synthetic fluorophlogopites ( Takeda and Donnay 1966;McCauley et al 1973;Takeda and Morosin 1975;Toraya et al 1978Toraya et al , 1983, but only a small number of studies concentrated on natural F-bearing micas.…”

Section: Introductionmentioning

confidence: 96%

Fluorophlogopite from Piano delle Concazze (Mt. Etna, Italy): Crystal chemistry and implications for the crystallization conditions

Scordari

Schingaro

Ventruti

et al. 2013

American Mineralogist

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Fluorine is an important proxy for magmatic differentiation processes in the shallow parts of volcanic plumbing systems. Fluorphlogopite is one of the more important fluorine carriers in magmatic rocks. In the present study, a full crystal chemical investigation of fluorophlogopite 1M from Piano delle Concazze, Mt. Etna volcano, Italy, is carried out. The fluorophlogopite occurs in a benmoreitic lava from prehistoric volcanic activity at Mt. Etna (post-caldera forming phase of the "Ellittico" eruptive center; ~15 ka BP). It is primarily associated with fluorapatite covered with amorphous SiO 2 and crystallized during syn/post-eruption pneumatolytic stages. The mica sample studied here is among the most Fe-and Ti-rich fluorophlogopite found in nature. EPMA data yielded the following mean chemical formula for this mineral (K 0.83 Na 0.13 )(Fe 2+ 0.44 Structure refinements on four fluorophlogopite crystals, performed in space group C2/m, converged at R = 0.03-0.04, with cell parameters in the ranges a = 5.323-5.324, b = 9.219-9.222, c = 10.116-10.119 Å, b = 100.1-100.3°. Major substitutions are OH -↔ F -,M 3+ -oxy ( VI M 2+ +OH -↔ VI M 3+ +O 2-) and Ti-oxy substitution: VI M 2+ +2(OH) -↔ VI Ti 4+ +2O 2-. The fluorophlogopite from Piano delle Concazze exhibits the shortest c-parameter with respect to other fluorophlogopites found in nature. The short c parameter is essentially due to the absence of the hydroxyl group in favor of F -and especially of O 2-and to the thus increased attractive interaction between the interlayer cation and the anion content (F -, O 2-) located at the O4 site. A comparison with other natural fluorophlogopites (namely from Biancavilla, Etna and Presidente Olegario, Brazil) show intermediate crystal-chemical features for the Piano delle Concazze fluorophlogopite. Particularly at Etna, differences in the chemical composition of the crystallized fluorophlogopites could be related to the various extent of enrichments by transfer of a gas phase achieved in specific parts of the volcanic plumbing system.

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Section: Introductionmentioning

confidence: 96%

Fluorophlogopite from Piano delle Concazze (Mt. Etna, Italy): Crystal chemistry and implications for the crystallization conditions

Scordari

Schingaro

Ventruti

et al. 2013

American Mineralogist

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“…Robert et al (1993), Papin et al (1997), and Boukili et al (2001) showed that F exhibits a strong preference for trioctahedral micas because in dioctahedral micas the hydroxyl proton is involved in hydrogen bonds with underbonded apical O atoms from the adjacent tetrahedral sheet, so the replacement of hydroxyl groups by F is difficult or impossible. On the contrary, in trioctahedral micas this replacement does not change significantly the local charge balance on tetrahedral O atoms; in addition the H + -K + repulsion is transformed into F --K + attraction, and therefore it is energetically favored.…”

Section: Introductionmentioning

confidence: 97%

“…The effects of F-OH replacement on the structure stability have attracted the attention of many researchers (Munoz 1984;Robert et al 1993;Papin et al 1997;Mason 1992;Boukili et al 2001;Fechtelkord et al 2003). It is well known that the presence of F enhances the thermal stability of the trioctahedral mica structure.…”

Section: Introductionmentioning

confidence: 98%

Fluorophlogopite from Biancavilla (Mt. Etna, Sicily, Italy): Crystal structure and crystal chemistry of a new F-dominant analog of phlogopite

Gianfagna

Scordari

Mazziotti-Tagliani

et al. 2007

American Mineralogist

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Fluorophlogopite, a new F-dominant mineral of the mica group, was found at Monte Calvario, Biancavilla, lower southwestern flanks of Mt. Etna volcano (Catania, Sicily, Italy). The mineral occurs in autoclasts of gray-red altered benmoreitic lavas, primarily associated with fluoro-edenite, alkali-feldspars, clino- and ortho-pyroxenes, fluorapatite, hematite, and pseudobrookite. It was formed by metasomatism of the original lava rocks from very hot fluid enriched in F, Cl, and other incompatible elements. Fluorophlogopite occurs as very thin laminae with a diameter of 200 to 400 μm. Main physical properties are pale yellow in color; yellowish-white in thin section; vitreous to resinous luster; transparent; non-fluorescent; Mohs’ hardness 2–3; brittle and malleable; perfect cleavage on {001}; biaxial (–), αcalc = 1.5430(8), β = 1.5682(5), γ = 1.5688(5) (λ = 589 nm); 2Vmeas = 17(2)°; α = acute bisectrix ⊥ (001); nonpleochroic; Dcalc = 2.830 g/cm3 (using empirical formula and single-crystal unit-cell parameters), Dcalc = 2.842 g/cm3 (using empirical formula and powder cell constants). Infrared spectrum did not show a significant absorption band in the OH-stretching region (3800–3600 cm–1) confirming that the F content of the fluorophlogopite from Biancavilla is close to the stoichiometric value. Unit-cell parameters from X-ray powder-diffraction data (114.6 mm diameter Gandolfi camera, CuKα) are a = 5.305(2), b = 9.189(3), c = 10.137(4) Å, β = 100.02(3)°. These data agree with those obtained by single-crystal X-ray studies on a very thin (~15 μm) fluorophlogopite crystal, i.e., Monoclinic (1M polytype); Space Group C2/m; a = 5.3094(4), b = 9.1933(7), c = 10.1437(8) Å, β = 100.062(5)°, V = 487.51(6) Å3, Z = 2. Structure refinements using anisotropic displacement parameters converged at R = 3.50, Rw = 4.37, Rsym = 3.72%. Electron microprobe analysis performed on the same crystal used for X-ray investigation gave: SiO2 = 45.75(39), TiO2 = 1.05(5), Al2O3 = 9.60(19), MgO = 27.92(30), MnO = 0.16(3), FeOtot = 1.25(6), BaO = 0.09(5), K2O = 8.22(11), Na2O = 0.61(30), Cl = 0.02(1) wt%. Secondary Ion Mass Spectrometry (SIMS) was used to estimate light elements [Li2O = 0.30(1) and H2O = 0.16(2) wt%] and fluorine content [F = 8.69(24) wt%]. The new mineral fluorophlogopite and its name were approved by IMA-CNMMN (2006/011)

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“…For these reasons, the 3600-3000-cm -1 range of the spectrum was simulated using the number of bands permitting a good fit (although they may not have necessarily a physical meaning). The number of bands varied between four and nine and all were Ganssian type (Papin et al, 1997). The positions were fixed in a first calculation and left free for the final calculation.…”

Section: Methodsmentioning

confidence: 99%

Quantification of Mixed-Layer Illite-Smectite in Glass Matrices by Fourier-Transform Infrared Spectroscopy

Fuente

Cuadros

Linares

2000

Clays and clay miner.

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Intersite OH-F distribution in an Al-rich synthetic phlogopite

Cited by 34 publications

References 0 publications

Fluorophlogopite from Piano delle Concazze (Mt. Etna, Italy): Crystal chemistry and implications for the crystallization conditions

Fluorophlogopite from Piano delle Concazze (Mt. Etna, Italy): Crystal chemistry and implications for the crystallization conditions

Fluorophlogopite from Biancavilla (Mt. Etna, Sicily, Italy): Crystal structure and crystal chemistry of a new F-dominant analog of phlogopite

Quantification of Mixed-Layer Illite-Smectite in Glass Matrices by Fourier-Transform Infrared Spectroscopy

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