Crystal structure and crystal chemistry of fluorannite and its relationships
                  to annite

Brigatti, Maria Franca; Caprilli, Enrico; Malferrari, Daniele; Mottana, Annibale

doi:10.1180/minmag.2007.071.6.683

Cited by 8 publications

(6 citation statements)

References 20 publications

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“…The maximum vertical spread of the plot in Figure 3 of α values in natural samples varies from natural fluorannite (0.57°, Brigatti et al 2007) to natural tetraferri-phlogopites (11.5°, Brigatti et al 1996b). More generally, the greater the F − content, the lower the in-plane rotation angle.…”

Section: Tetrahedral Sheetmentioning

confidence: 98%

“…Relation between the tetrahedral and octahedral sheet thickness, interlayer separation and c sin(β). Symbols: Open symbols = phlogopites characterized by Ti and Fe 3+ -oxy substitutions and no tetraferri-phlogopite component (square: Scordari et al 2006;circle: Scordari et al 2008;triangle pointing upward: Matarrese et al 2008;triangle pointing downward: Lacalamita 2009); open symbols with cross = natural end-member annite and synthetic near end-member phlogopite (circle: Redhammer and Roth 2002) and fluorannite (square: Brigatti et al 2007); open symbols with plus = tetraferri-phlogopites (square: Brigatti et al 1996a;circle: Brigatti et al 1996b); open symbols with horizontal line = fluorophlogopites (square: Takeda and Donnay 1966;circle: Joswig 1972;triangle pointing upward: Hazen and Burnham 1973;triangle pointing downward: McCauley et al 1973;diamond: Takeda and Morosin 1975); open symbols with vertical line = other fluorophlogopites (square: Hazen et al 1981;circle: Russell and Guggenheim 1999;triangle pointing upward: Gianfagna et al 2007); solid symbols = Ti-rich fluorophlogopites of this study (Ma1). Average standard deviations for the study samples are reported in the graph, close to the axes origin.…”

Section: Tetrahedral Sheetmentioning

confidence: 99%

“…A review of studies on fluorophlogopites is found in Gianfagna et al (2007), whereas Brigatti et al (2007) performed a crystal structure analysis of the end-member fluorannite.…”

Section: Introductionmentioning

confidence: 99%

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Crystal chemistry of Ti-rich fluorophlogopite from Presidente Olegario, Alto Paranaiba igneous province, Brazil

Schingaro

Lacalamita

Scordari

et al. 2011

American Mineralogist

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Trioctahedral micas from kamafugitic lavas of Presidente Olegario (Brazil) are Ti-Fe-bearing fluorophlogopites. They were investigated using a combination of electron probe microanalysis (EPMA), single-crystal X-ray diffraction (SCXRD), and Mössbauer spectroscopy.EPMA data yielded the following ranges: Al2O3 (8.7–10.1 wt%), MgO (19.6–20.6 wt%), FeO (5.7–6.5 wt%), TiO2 (5.9–7.5 wt%), K2O (8.9–9.7 wt%), Na2O (0.4 –0.6 wt%), and fluorine (3.4–4.1 wt%). Mössbauer investigation indicated: VIFe2+ ∼ 60%, VIFe3+ ∼ 10%, IVFe3+ ∼ 30%. X-ray analysis indicated the 1M polytype, with cell parameters in the range a = 5.3208–5.3376, b = 9.2210–9.2464, c = 10.1227–10.155 Å, β = 100.157–100.194°. Structure refinements using anisotropic displacement parameters were performed in space group C2/m and converged to 2.01 ≤ R1 ≤ 3.51, 2.00 ≤ wR2 ≤ 3.51%.The micas have no VIAl3+ and Na is probably partitioned over both interlayer and octahedral sites. Major substitutions are OH− ↔ F−, and the Ti-oxy substitution: VIM2+ + 2(OH)− ↔ VITi4+ + 2O2– + H2↑. Accordingly, the structural features of the studied micas encompass those typical of both fluorophlogopites and micas affected by Ti-oxy substitutio

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Section: Tetrahedral Sheetmentioning

confidence: 98%

Section: Tetrahedral Sheetmentioning

confidence: 99%

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Crystal chemistry of Ti-rich fluorophlogopite from Presidente Olegario, Alto Paranaiba igneous province, Brazil

Schingaro

Lacalamita

Scordari

et al. 2011

American Mineralogist

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“…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. However, recently, Gianfagna et al (2007) performed a crystal-structure analysis of * E-mail: fernando.scordari@uniba.it the end-member F-bearing phlogopite from Biancavilla (Etna) that had been approved by the IMA-CNMMN as a new mineral with the name fluorophlogopite, whereas Brigatti et al (2007) carried out a structural study of a fluorannite emphasizing the structural changes due to F content with respect to annite. Schingaro et al (2011) studying various F-rich phlogopite from kamafugitic lavas of Presidente Olegario (Brazil) with the highest Ti content in nature and with a minor tetraferriphlogopite component, discuss the mechanisms of Ti and Fe incorporation in the phlogopite structure.…”

Section: Introductionmentioning

confidence: 98%

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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“…The diffraction peak at 2θ = 8.7 • (1.0 nm) is attributed to the characteristic peak for some mica group silicate. [27,28] Comparison of the XRD patterns of VMT and OVMT showed that the location of the 8.7 • peak did not change after the ion exchange reaction.…”

Section: Downloaded By [Uq Library] At 17:50 01 November 2014mentioning

confidence: 98%

Synergistic Effect of Organic Vermiculite on the Flame Retardancy and Thermal Stability of Intumescent Polypropylene Composites

Chen

Wang

Kang

et al. 2013

Journal of Macromolecular Science, Part B

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Organic vermiculite (OVMT) prepared from vermiculite (VMT), with high aspect ratio and orderly arranged platelets intercalated by octadecyl trimethyl ammonum bromide (OTAB), was used as a synergistic agent on the flame retardancy of a polypropylene/intumescent flame retardant (PP/IFR) system. The flammability and thermal stability of PP/IFR/OVMT composites were investigated by limiting oxygen index (LOI), UL-94 testing, cone calorimetry tests, and thermogravometric analysis. The results of LOI and UL-94 testing showed that low loading of OVMT improved the flame retardancy and retarded dripping for PP/IFR composites. OVMT, with 1% loading, increased the char residue of PP/IFR composites and could act as an effective additive for improvement in flame retardancy, which was confirmed by the cone data. The char layer morphological structures observed by scanning electron microscopy (SEM) showed that OVMT with 1% loading can promote formation of a continuous and compact intumescent char layer. Raman spectroscopy results indicated that the OVMT or its pyrolytic products led to a decrease in size of the carbonaceous micro-domain during combustion, resulting in formation of more compact charred layers. Thus, OVMT with 1% loading showed a synergistic effect with IFR in the combustion of the PP/IFR composites.

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Crystal structure and crystal chemistry of fluorannite and its relationships to annite

Cited by 8 publications

References 20 publications

Crystal chemistry of Ti-rich fluorophlogopite from Presidente Olegario, Alto Paranaiba igneous province, Brazil

Crystal chemistry of Ti-rich fluorophlogopite from Presidente Olegario, Alto Paranaiba igneous province, Brazil

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

Synergistic Effect of Organic Vermiculite on the Flame Retardancy and Thermal Stability of Intumescent Polypropylene Composites

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