Two zoned pegmatites in south-eastern Minas Gerais were sampled in detail for their content of monazite and xenotime and the monazite was analysed for certain of the rare-earth elements and thorium. The ratio of xenotime to monazite increases in both pegmatites from the wall toward the quartz core. The content of the less basic rare-earth elements and of thorium in monazite rises in the same direction. These variation trends suggest that during the crystallization of these pegmatites there was a fractionation of the elements leading to a more or less steady enrichment of the less basic rare-earth elements and of thorium in the residual fluids. One mode of explaining these observed effects postulates that the rare-earth elements and thorium were present in pegmatitic fluids as co-ordination complexes rather than as simple cations. © 1959.
CITATION STYLE
Murata, K. J., Dutra, C. V., da Costa, M. T., & Branco, J. J. R. (1959). Composition of monazites from pegmatites in eastern Minas Gerais, Brazil. Geochimica et Cosmochimica Acta, 16(1–3), 1–14. https://doi.org/10.1016/0016-7037(59)90043-2
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