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Three polytypes of lepidolite from Czechoslovakia |
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| Institution: | a Dept. of Earth Sciences, Univ. of Manitoba, Winnipeg 19, Man., Canada b Inst. of Geological Sciences, Charles University, Praha, Czechoslovakia c Inst. für Mineralogie, Ruhr-Universität Bochum, Germany |
| Abstract: | The micas come from two pegmatites penetrating serpentinite in Western Moravia, Czechoslovakia. The lepidolite from Biskupice is chemically halfway between polytithionite and trilithionite, and exhibits the 2M1 structure which so far was unknown in natural lepidolites. The optical axial plane is perpendicular to (010). In lepidolite crystals from Radkovice, the 2M2 structure predominates over 1M. The composition is close to trilithionite. The optic axial plane is parallel to (010). Refractive indices, densities, and cell volumes are similar, but the IR absorption spectrum, thermal behaviour, and 2V are different from the corresponding parameters in lepidolite from Biskupice. |
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