Fluorine in micas: crystal-chemical control of the OH-F distribution between trioctahedral and dioctahedral sites

Robert, Jean-Louis; Bény, Jean-Michel; Ventura, Giancarlo Della; Hardy, Michel

doi:10.1127/ejm/5/1/0007

Cited by 73 publications

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“…F enters preferentially the trioctahedral Li-bearing sites when it replaces OH, whereas hydroxyls are adjacent to the vacant octahedral sites. Thus, the OH-stretching bands of Li-bearing micas result from dioctahedral hydroxyls, and correspond to the same OH-stretch wavenumber as muscovite (~3629 cm À1 ) (Robert et al, 1989(Robert et al, , 1993 (Fig. 6aÀd).…”

Section: Structural Characteristicsmentioning

confidence: 94%

Micas of the muscovite–lepidolite series from Karibib pegmatites, Namibia

Roda¹,

Keller²,

Pesquera³

et al. 2007

Mineral. mag.

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Micas of the muscoviteÀlepidolite series are main constituents of the evolved pegmatites from the Okatjimukuju-Kaliombo portion of the Karibib belt, Namibia. The compositional variations shown by the micas from the intermediate zones are mainly controlled by the Li 3 Al À1 & À2 and SiLi 2 Al À2 & À1 substitution schemes, whereas for the micas from the core margins and the replacement bodies, only the first of these two exchange vectors seems to operate. The chemical composition of the micas not only depends on the degree of pegmatite evolution, but also on the position in the internal zonation of the pegmatite. Micas from the core margins and the replacement units are generally richer in F, Li, Rb, Cs and Zn than those from the intermediate zones. In general, the contents of these elements increase with decreasing K/Rb ratio. However, some data departing from this general trend are also observed, which could be related to subsolidus processes. Some pegmatite bodies show a complete internal evolution, developed from the margins to the core zone, which is reflected in the chemical composition of the micas. The regional distribution of pegmatites does not define a zonation, because an overlapping of pegmatites with different degrees of evolution occurs. This could be due to the high level of evolution attained by most of the rare-element pegmatites, and to their topography with respect to a dome structure of the basement.

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Section: Structural Characteristicsmentioning

confidence: 94%

Micas of the muscovite–lepidolite series from Karibib pegmatites, Namibia

Roda¹,

Keller²,

Pesquera³

et al. 2007

Mineral. mag.

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“…The Li content in these compositions was calculated on the assumption that the atomic Li/F ratio is 1. This approach frequently used to calculate Li contents in micas, which cannot be determined by electron microprobe, is based not only on empirical data but also has theoretical substantiation, because F -is coor dinated largely by Li + (Munoz, 1963;Robert et al, 1993;ern et al, 2003).…”

Section: Physical Properties and Opticalmentioning

confidence: 98%

“…Refractive indexes are γ = 1.590(3) and β = 1.586(3). Measure ment of α was unsuccessful because flakes in the immersion sample lie parallel to the cleavage plane; calculated α is 1.511(10). No optic axis dispersion has been observed.…”

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confidence: 95%

Voloshinite, a new rubidium mica from granitic pegmatite of Voron’i Tundras, Kola Peninsula, Russia

et al. 2010

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Voloshinite, a new mineral of the mica group, a rubidium analogue of lepidolite, has been found from the rare element granitic pegmatite at Mt. Vasin Myl'k, Voron'i Tundras, Kola Peninsula, Russia. It is closely associated with pollucite and lepidolite and commonly with muscovite, albite, and quartz; K,Rb feld spar, rubicline, spodumene, montebrasite, and elbaite are among associated minerals as well. Voloshinite, a late mineral that formed after pollucite, commonly fills polymineralic veinlets and pods within the pollucite aggregates. It occurs as rims up to 0.05 mm thick around lepidolite, as intergrowths of tabular crystals up to 0.25 mm in size, and occasionally replaces lepidolite. The new mineral is colorless, transparent, with vitreous luster. Cleavage is eminent parallel to {001}; flakes are flexible. The calculated density is 2.95 g/cm 3 . The new mineral is biaxial (-), with 2V = 25°, α calc = 1.511, β = 1.586, and γ = 1.590. The optical orientation is Y = b, Z = a. The chemical composition of the type material determined by electron microprobe (average of five point analyses; Li has been determined with ICP OES) is as follows (wt %): 0.(OH) 0.60 ) Α2 . The idealized formula is as follows: Rb(LiAl 1.5 ᮀ 0.5 )[Al 0.5 Si 3.5 O 10 ]F 2 . Voloshinite forms a continuous solid solution with lepidolite. According to X ray single crystal study, voloshinite is monoclinic, space group C2/c. The unit cell dimensions are: a = 5.191, b = 9.025, c = 20.40 Å, β = 95.37°, V= 951.5 Å 3 , Z = 4. Polytype is 2M 1 . The strongest reflections in the X ray powder diffraction pattern (d, Å-I[hkl]) are: 10.1-60[001]; 4.55-80[020, 110, 111]; 3.49-50[114]; 3.35-60[024, 006]; 3.02-45[025]; 2.575-100[116, 131, 202, 132], 2.017-50[136, 0.0.10]. The mineral was named in honor of A.V. Voloshin (born in 1937), the famous Russian mineralogist. The type material is deposited at the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow.

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“…Existen diversos trabajos que han abordado esta problemática, sobre todo en el sector de cerámicas estructurales, poniendo especial atención a las emisiones de flúor, cloro y azufre (11)(12)(13)(14), la relación con la mineralogía de las arcillas (15)(16)(17)(18) y sus mecanismos de emisión y control (19)(20)(21)(22).…”

Section: Generalidadesunclassified

Utilización de técnicas acopladas de análisis térmico TG-DSC-QMSFTIR en la caracterización de arcillas y composiciones cerámicas utilizadas en la fabricación de baldosas cerámicas. Cuantificación de compuestos de carbono

Gómez¹,

Gazulla²,

Zumaquero³

et al. 2007

Bol. Soc. Esp. Ceram. Vidr.

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En el presente estudio se ha desarrollado una metodología de trabajo para el análisis de emisiones gaseosas (EGA) en materias primas arcillosas y composiciones cerámicas utilizadas en la fabricación de baldosas cerámicas mediante técnicas acopladas de análisis térmico (TG-DSC-QMS-FTIR). Se caracterizaron los distintos tipos de emisiones (CO 2 , CO, NO x , F, SO x ) que se emiten durante un ciclo térmico hasta una temperatura máxima de 1200ºC. Asimismo, se evaluó la posibilidad de la utilización de la técnica para la cuantificación de dichas emisiones. En concreto se ha realizado la cuantificación de emisiones de CO 2 procedentes de la presencia de carbono orgánico e inorgánico en materiales arcillosos. Se han validado las medidas con distintos materiales de referencia y se han comparado los resultados con los obtenidos con otras técnicas de análisis, tales como la termogravimetría (TG), calcimetría y culombimetría. La técnica de análisis térmico (TG-DSC-QMS-FTIR) es de utilidad en el estudio de emisiones a escala de laboratorio, presentando baja incertidumbre para la cuantificación de compuestos de carbono. Además, la técnica es útil para la determinación del origen mineralógico de los elementos presentes en las emisiones. Palabras clave: Emisiones gaseosas, Arcillas, Análisis térmico, Dióxido de Carbono, Carbono orgánico, Carbonatos. Use of coupled TG-DSC-QMS-FTIR thermal analysis techniques in characterizating clays and ceramic compositions used in ceramic tile manufacture. Quantification of carbon compoundsIn this study, a work methodology has been developed for t evolved gas analysis (EGA) in clay raw materials and ceramic compositions used in ceramic tile manufacture using coupled thermal analysis techniques (TG-DSC-QMS-FTIR). The different types of gases (CO 2 , CO, NO x , F, SO x ) evolving from these raw materials during a thermal cycle up to a peak temperature of 1200ºC were characterised. The possibility of using this calorimeter for the quantification of the CO 2 gases evolving from the organic and inorganic carbon (carbonates) present in the studied clay materials was also evaluated. The measurements were validated with different reference materials, and the results were compared with those obtained with other analysis techniques, such as thermogravimetry (TG), calcimetry, and coulometry. The thermal analysis technique (TG-DSC-QMS-FTIR) is a suitable technique for analysing evolved gases with low uncertainties for carbon compounds quantification. Furthermore, the methodology allows the mineralogical origin identification of the elements present in the evolved gases.

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Fluorine in micas: crystal-chemical control of the OH-F distribution between trioctahedral and dioctahedral sites

Cited by 73 publications

References 0 publications

Micas of the muscovite–lepidolite series from Karibib pegmatites, Namibia

Micas of the muscovite–lepidolite series from Karibib pegmatites, Namibia

Voloshinite, a new rubidium mica from granitic pegmatite of Voron’i Tundras, Kola Peninsula, Russia

Utilización de técnicas acopladas de análisis térmico TG-DSC-QMSFTIR en la caracterización de arcillas y composiciones cerámicas utilizadas en la fabricación de baldosas cerámicas. Cuantificación de compuestos de carbono

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