Cs-bearing beryl evolving to pezzottaite from the Julianna pegmatitic system, SW Poland
Cs-bearing beryl evolving to pezzottaite from the Julianna pegmatitic system, SW Poland (in A tribute to Frank Christopher Hawthorne, Lee A. Groat (prefacer))
The Canadian Mineralogist (January 2016) 54 (1): 115-124
- alkali metals
- anatexite
- beryl
- Central Europe
- cesium
- chemical composition
- color
- crystal structure
- Europe
- formula
- granites
- igneous rocks
- infrared spectra
- Lower Silesia
- metals
- metamorphic rocks
- migmatites
- minor elements
- pegmatite
- plutonic rocks
- Poland
- Polish Sudeten Mountains
- Raman spectra
- ring silicates
- silicates
- spectra
- Sudeten Mountains
- unit cell
- X-ray diffraction data
- pezzottaite
- Pilawa Gorna Poland
- Julianna pegmatite system
Beryl is a common accessory mineral in the hybrid NYF + LCT Julianna pegmatite system, exposed in a quarry at Pilawa Gorna in Lower Silesia, SW Poland. In pods with the LCT-type mineralization it forms zoned, yellowish, white to pinkish, Cs-enriched crystals (up to 16.56 Cs (sub 2) O wt.%) with compositions at the crystal rims evolving to pezzottaite, i.e, a Cs-dominant mineral of the beryl group, with the empirical formula: (Cs (sub 0.755) Na (sub 0.059) Ca (sub 0.024) K (sub 0.008) Rb (sub 0.006) (sub 0.148) ) (sub Sigma 1) (Be (sub 1.993) Li (sub 0.961) Si (sub 0.046) ) (sub Sigma 3) (Al (sub 1.993) Mn (sub 0.007) ) (sub Sigma 2) [Si (sub 6) O (sub 18) ]. Textural evidence indicates that the Cs-bearing beryl crystallized from a residual melt with high contents of fluxes and pezzottaite from hydrothermal fluids with Cs concentrations increased significantly due to crystallization of cleavelandite that suppressed the activity of Na. The Julianna pegmatitic system at Pilawa Gorna is the third confirmed occurrence of pezzottaite worldwide. The mineral, similarly to pezzottaite in the type occurrence in Madagascar, formed in a pegmatite with a hybrid NYF + LCT signature.
