Bohseite-bavenite from intragranitic NYF pegmatites of the Třebíč Pluton
| Authors | |
|---|---|
| Year of publication | 2019 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | Bavenite and bohseite are beryllosilicates with a general formula Ca4Be4-xAlxSi9O24+x(OH)4-x. Although bavenite (x=2) is widespread and long-known beryllium mineral in granitic pegmatites, often as a hydrothermal product of beryl breakdown, bohseite (x=0) was defined in last decade. Compositions with Be=2.95-3.85 apfu in bavenite-bohseite from NYF pegmatites of the Třebíč Pluton, Moldanubian zone, Czech Republic represents one of the most Al-poor bohseite known to date. Their typical mineral association and composition are related to the primary precursor: a) beryl-hosted bavenite-bohseite forms veinlets and nests (with rare Mg-bazzite) in primary beryl b) rare replacement of milarite c) helvite/danalite-hosted rims, veinlets and pseudomorphoses d) phenakite-hosted veinlets and pseudomorphoses Regarding the variability of Al-content, decreasing trend from Al-rich, beryl-hosted to Al-very low, phenakite-hosted environment, could be seen. Hence, the chemical composition of bavenite-bohseite solid solution mirrors the chemical compositions of replaced primary phases in the local environment and shows low Al mobility at such conditions. |
| Related projects: |