ISSN

print 2570-7337
online 2570-7345

Bohseite from beryl-columbite pegmatite D6e in Maršíkov (Silesicum, Czech Republic)


Volume 28, issue 1 (2020), pages 219-223
DOI: https://doi.org/10.46861/bmp.28.219

Keywords

Abstract

Bohseite was found in a lenticular body of D6e beryl-columbite granitic pegmatite near Maršíkov, which is hosted by amphibole gneisses of the Sobotín Amphibolite Massif (Silesicum, northeastern part of Czech Republic). Bohseite forms chalky white aggregates up to 1 cm in size, which are hosted by small vugs in the coarse-grained pegmatite. It is associated with small crystals of quartz, adularia, albite, muscovite and epidote. Bohseite is orthorhombic, space group Cmcm with following unit-cell parameters refined from X-ray powder diffraction data: a 23.210(2), b 4.955(2), c 19.428(3) Å and V 2234.5(1.0) Å3. The electron microprobe compositional data of bohseite are presented. Bohseite from Maršíkov contains 14.3 - 42.5 mol. % of bavenite component, up to 0.06 apfu Na and 0.13 - 0.36 apfu F. The association with other beryllium-rich phases (milarite, bertrandite) points to variable activities of Be and Al during hydrothermal stage of evolution of the pegmatite body. The likely source of Be was beryl, which is sometimes completely dissolved and vugs after its crystals are lined by small crystals of above mentioned hydrothermal phases.

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