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Hambergite-rich melt inclusions in morganite crystals from the Muiane pegmatite, Mozambique and some remarks on the paragenesis of hambergite
journal contributionposted on 2023-05-17, 05:08 authored by Thomas, R, Paul DavidsonPaul Davidson
Raman spectroscopic studies of daughter crystals of hambergite [Be 2BO 3(OH, F)] in primary melt and secondary fluid inclusions in morganite crystals from the Muiane pegmatite, Mozambique, show that the inclusions have extremely high beryllium concentrations, corresponding to as much as 10.6% (g/g) in melt inclusions and 1.25% (g/g) BeO in fluid inclusions. These melt and fluid inclusions were trapped at about 610Â°C and 277Â°C, respectively. We propose two possible mechanisms for the formation of the hambergite crystals: (i) direct crystallization from a boron- and beryllium-rich pegmatite-forming melt or (ii) these are daughter crystals produced by the retrograde reaction of the boron-rich inclusion fluid with the beryl host, after release of boric acid from the primary trapped metastable volatile-rich silicate melt during cooling and recrystallization. Although we favor the second option, either case demonstrate the extent to which Be maybe concentrated in a boron-rich fluid at relatively high temperatures, and in which species of Be maybe transported. One important constraint on the stability of the hambergite paragenesis is temperature; at temperatures of â‰¥650Â°C (at 2 kbar) hambergite is not stable and converts to bromellite [BeO]. Â© 2010 Springer-Verlag.
Publication titleMineralogy and Petrology
Department/SchoolSchool of Natural Sciences
Place of publicationSachsenplatz 4-6, Po Box 89, Vienna, Austria, A-1201