Summary
Within the Nkombwa Hill carbonatite complex, bastnäsite-(Ce), (Ce,La)CO3F, has been identified as an abundant mineral in xenoliths hosted by late-stage ferrocarbonatite sills and dykes. Bastnäsite-(Ce) occurs as fibrous yellow crystals, about 1 µm in size, replacing monazite and in association with baryte, in a matrix of dolomite. In common with bastnäsite-(Ce) from other locations, the bastnäsite-(Ce) of Nkombwa Hill contains up to 70% RE2O3, almost entirely as light rare-earth oxides. However, Nkombwa Hill bastnäsite-(Ce) is relatively deficient in La and enriched in Pr and Nd.
Zusammenfassung
Im Karbonatit-Komplex von Nkombwa Hill kommt Bastnäsit-(Ce), (Ce-La) CO3F, als eine weitverbreitete Komponente in Xenolithen in späten Ferrokarbonatit-Lagergängen und Gängen vor. Bastnäsit-(Ce) bildet faserige gelbe Kristalle in einer Matrix aus Dolomit, die ungefähr 1 µm groß sind, Monazit verdrängen und mit Baryt assoziiert sind. Ähnlich wie Bastnäsit von anderen Lokalitäten, enthält auch dieser bis zu 70% RE2O3 fast ausschließlich als Oxide der Leichten Seltenen Erden. Der Bastnäsite-(Ce) von Nkombwa Hill ist jedoch relativ verarmt an La und an Pr und Nd angereichert.
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Zambezi, P., Hale, M., Voncken, J.H.L. et al. Bastnäsite-(Ce) at the Nkombwa Hill carbonatite complex, Isoka District, Northeast Zambia. Mineralogy and Petrology 59, 239–250 (1997). https://doi.org/10.1007/BF01161861
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DOI: https://doi.org/10.1007/BF01161861