J. Phys. IV France 123 (2005) 331-335
Titanium and barium incorporation into the phyllosilicate phases: The example of phlogopite-kinoshitalite solid solutionA. Ibhi, H. Nachit and H. El Abia
LPMM, Faculty of Science, Ibn Zohr University, BP. 8106, Agadir, Morocco
Extremely high abundances of BaO (up to 21.46 wt. % ) and TiO2 (up to 13.85 wt. % ) are reported from brown phlogopite in calcite carbonatite inclusions from Jbel Saghro, Anti-Atlas Morocco. The substitution of Ba into the phlogopite structure can be explained by the scheme Ba + Al K + Si. At least 50 % of the K on the interlayer sites of phlogopites from Saghro is replaced by Ba. The incorporation of Ba into phlogopite allow the occurence of kinochitalite phases. Al compensates for tetrahedral Si deficiencies, and Ti is probably limited to octahedral substitution for Mg and Fe. A substitution scheme of the type Ba2+ + 2Ti4+ + 3Al K+ + 3(Mg, Fe)2+ + 3Si4+ is proposed.
© EDP Sciences 2005