Publication details
Role of early cordierite crystallization on tourmaline composition in rare-element pegmatites Věžná I and Hrotovice
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| Year of publication | 2021 |
| Type | Conference abstract |
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| Description | Lithium-poor pegmatites Věžná I (VZ) and Hrotovice (HR), Moldamubian Zone, Czech Republic contain common early cordierite (VZ) or sekaninaite (HR) in intermediate (graphic) units along with tourmalines mostly present in more evolved units. Both pegmatites (especially Hrotovice) contain a large part of their bulk Li in cordierite-group minerals; only very little Li is present in the late-stage fractionated units. Much higher proportion of Li,Be-rich sekaninaite in Hrotovice enabled origin of very limited volume of Li-rich minerals with very rare Fe-rich elbaite and lepidolite whereas in Věžná I elbaite and polylithionite are more common. Early cordierite crystallization likely depleted the pegmatite melt in Li and Be due to their relatively high compatibility in cordierite. The depletion should be less effective for Li which is considered incompatible element in cordierite (Evensen and London 2003). It manifests that crystallization of high amount of early Fe,Mg-minerals such as biotite, cordierite in outer units may significantly decrease amount of Li in the system available for crystallization of Li-minerals (e.g., elbaite and lepidolite) in the pegmatite. |