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Montmorillonite alteration of tourmaline from the Quintos de Baixo pegmatite, Borborema Pegmatite Province, NE Brazil (CROSBI ID 565486)

Prilog sa skupa u zborniku | sažetak izlaganja sa skupa | međunarodna recenzija

Strmić Palinkaš, Sabina ; Bermanec, Vladimir ; Žigovečki Gobac, Željka ; Palinkaš, Ladislav Antun ; Kampić, Štefica ; Wegner, Reinhard ; Odúlio, José Marensi Moura Montmorillonite alteration of tourmaline from the Quintos de Baixo pegmatite, Borborema Pegmatite Province, NE Brazil // Acta mineralogica-petrographica, Abstract series, Volume 6 (special selection) MECC2010 / Zaharia, Luminiţa, Kis, Annamária, Topa, Boglárka, Papp, Gábor, Weiszburg, Tamás G. (ur.). Segedin: University of Szeged, 2010. str. 99-99

Podaci o odgovornosti

Strmić Palinkaš, Sabina ; Bermanec, Vladimir ; Žigovečki Gobac, Željka ; Palinkaš, Ladislav Antun ; Kampić, Štefica ; Wegner, Reinhard ; Odúlio, José Marensi Moura

engleski

Montmorillonite alteration of tourmaline from the Quintos de Baixo pegmatite, Borborema Pegmatite Province, NE Brazil

Tourmaline is a common boron-rich mineral in granitic pegmatites. It is resistant to weathering and typically occurs as a detrital mineral in sedimentary rocks and soils. However, tourmaline in pegmatites may be partially altered to various aluminous minerals. Alterations are mostly associated with late magmatic and hydrothermal fluids. Tourmaline from the Quintos de Baixo pegmatite, Borborema Pegmatite Province, NE Brazil, displays zonal structure with Li-Al-rich core (elbaite) and Fe-rich rim (schorl). The core is frequently altered to clay minerals. Matrix between tourmaline crystals comprises clay minerals as well. According to X-ray powder diffraction (XRPD) analysis the principal clay mineral is montmorillonite with cation exchange capacity (CEC) of 75.5 ± 0.4 mEq/100g. The following reaction illustrates breakdown of tourmaline (elbaite) into Li-montmorillonite: Na(Li, Al)3Al6(BO3)3Si6O18(OH)4 + 5H4SiO4 + 3H+ ↔ 3[Al3(Si3.67Al0.33)O10(OH)2]Li0.33 + 3H3BO3 + 2Li+ + Na+ + 6H2O (rG0 = -69.7 kcal/mol). The reaction requires increased activity of H4SiO4 and points to the influence of late magmatic or hydrothermal fluids. Alternatively, the weathering of spodumene can represent an important source of montmorillonite: 7LiAlSi2O6 + 6H+ + 6H2O ↔ 3[Al3(Si3.67Al0.33)O10(OH)2]Li0.33 + 3H4SiO4 + 6Li+ (rG0 = -2.6 kcal/mol) Gibbs free energies for above mentioned reactions (rG0) have been estimated according to the thermodynamic data published by Woods & Garrels (1987), Tardy & Garrels (1974) and Ogorodova et al. (2004).

tourmaline; Quintos de Baixo pegmatite; montmorillonitic alteration

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Podaci o prilogu

99-99.

2010.

objavljeno

Podaci o matičnoj publikaciji

Acta mineralogica-petrographica, Abstract series, Volume 6 (special selection) MECC2010

Zaharia, Luminiţa, Kis, Annamária, Topa, Boglárka, Papp, Gábor, Weiszburg, Tamás G.

Segedin: University of Szeged

0324-6523

Podaci o skupu

5th Mid-European Clay Conference (MECC2010)

poster

25.08.2010-29.08.2010

Budimpešta, Mađarska

Povezanost rada

Geologija