Bazzit Be₃Sc₂Si₆O₁₈ z lokality Kožichovice II, nový minerál pro NYF pegmatity třebíčského plutonuČlánek v PDF
Bazzite Be3Sc2Si6O18 from the locality Kožichovice II, new mineral for NYF pegmatites of the Třebíč Pluton, Czech Republic
Bazzite was identified using electron microprobe as very rare secondary phase after primary beryl at euxenite-subtype pegmatite Kožichovice II. Small elongated euhedral crystals, up to 50 μm long, occur in thin vein (quartz ~ bavenite > beryl II ~ kaolinite(?) > bazzite) cutting and replacing euhedral crystal of primary beryl I. Bazzite is Na,Mg,Fe-enriched showing high contents of Sc (1.13–1.22 apfu; 12.79–13.80 wt.% Sc2O3), Mg (0.41–0.64 apfu; 2.73–4.23 wt.% MgO), Na (0.38–0.48 apfu; 1.96–2.43 wt.% Na2O), Fe (0.09–0.33 apfu; 1.07–3.91 FeOtot), Ca (0.10–0.16 apfu; 0.91–1.53 wt.% CaO), and Mn (0.02–0.03 apfu; 0.23–0.40 wt.% MnO). High concentrations of Mg, Fe and Na and negative correlation R+ + R2+/R3+ indicate the substitution CH◻ OR3+ = CHR+OR2+ in bazzite. Bazzite from Kožichovice differs from other bazzite in granitic pegmatites by Mg >> Fe and high Ca contents. It is likely the only known secondary bazzite formed after primary beryl I besides secondary bazzite after thortveitite. Bazzite (both primary and secondary) typically crystallized later than beryl in granitic pegmatites.
Milan Novák, Department of Geological Sciences, Masaryk University, Brno, Kotlářská 2, 611 37 Brno, Czech Republic, email@example.com