Lithium-bearing micas from elbaite-subtype pegmatites in the Western Moravia, Czech RepublicArticle PDF
Lithium-bearing micas from elbaite-subtype pegmatites in the Western Moravia, Czech Republic
Lithium-bearing micas from elbaite-subtype pegmatites of the Moldanubian Zone, western Moravia were examined using electron microprobe and the contents of Li2O were calculated (method of TISCHENDORF et al. 1997). Very rare to minor Li-bearing micas occur in albite unit or in pockets as pink, pale violet to colorless small flakes or aggregates associated with schorl or elbaite. All studied samples exhibit Si = 7.11–7.89 apfu; this corresponds to ~60–90 mol. % of polylithionite component. Vacancy in the octahedral position suggests presence of dioctahedral mica (muscovite or hypothetical mica with Si = 8 apfu). The compositional evolution (Si, Al, F, Licalc) implies increasing of polylithionite component during crystallization as in lepidolite-subtype pegmatites. Calculation of Li2O (method of TISCHENDORF et al. 1997) is only approximate, it is not feasible for polylithionite-rich Li-bearing micas.
Lukáš Zahradníček, National Museum, Cirkusová 1740, Praha 9 – Horní Počernice, Czech Republic, email@example.com
Milan Novák, Institute of Geological Sciences, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic