Acta Musei Moraviae

Lithium tourmalines from the lepidolite pegmatite at Sedlatice near Telč (Moldanubicum, western Moravia)

The lepidolite-subtype pegmatite at Sedlatice features simple mineralogy with garnet, apatite, tourmaline, andalusite, cordierite?, cassiterite, manganocolumbite, zircon and topas as accessory phases. Tourmaline is represented by common schorlitic tourmaline, with rare thin rims of green tourmaline (verdelite). Rare verdelite was found together with muscovite in quartz, its composition ranges from F-rich elbaite to fluorelbaite with elevated Fe and Mn contents. Very rare pink to white tourmaline replaced by illite and rimmed by trilithionite-polylithionite was found in albite-lepidolite zone. Its composition varies among F-rich elbaite, fluor-elbaite and rossmanite. The compositional variation of tourmaline is similar to the general trend known from lepidolite-subtype pegmatites. Replacement of tourmaline by illite is most probably result of alteration by late hydrothermal fluids.