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Visible and short-wave infrared reflectance spectroscopy of REE phosphate minerals

  • David J. Turner EMAIL logo , Benoit Rivard and Lee A. Groat
Published/Copyright: September 30, 2016
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American Mineralogist
From the journal American Mineralogist Volume 101 Issue 10

Abstract

Reflectance spectroscopy in the visible to short-wave infrared regions (500 to 2500 nm) was carried out using natural samples of the rare earth element (REE) phosphate minerals monazite, xenotime, and britholite. Samples were characterized by scanning electron microscopy and electron microprobe analysis. Absorption band positions were recorded with their probable origins, and spectral variability among the samples is discussed. Spectral features of these minerals are driven primarily by 4f-4f intraconfigurational electronic transitions of trivalent lanthanides. The distinct REE distributions of monazite, xenotime, and britholite drive their bulk spectral patterns, which in turn are sufficiently distinct to enable spectral classification. Spectral variability of some specific REE-related absorptions are interpreted to be driven by differences of the co-ordination polyhedra for the lanthanide cations between the crystal structures. Spectra of these minerals were also compared against carbonatite-hosted REE bearing fluorapatite. The work presented here strengthens the growing foundation for the interpretation of reflectance spectra of these REE phosphate minerals and enables exploitation of the observed features by the remote sensing community for detection, identification, and quantification of REE phosphate minerals. This is especially relevant for hyperspectral imaging spectroscopy with high spatial resolution, where the spectral response of a pixel becomes increasingly dominated by mineralogy.

Keywords: Hyperspectral; reflectance; spectroscopy; rare earth elements; REE; xenotime; monazite; britholite

Acknowledgments

Tony Mariano and Michel Picard (Canadian Museum of Nature) are thanked for their help with acquiring samples, and Jilu Feng and Steve Creighton for their help with data collection. Financial support is acknowledged from the Natural Sciences and Engineering Research Council of Canada. T.C. Chudy is thanked for his help and insight with the fluorapatite-bearing Fir carbonatite sample. The reviewers provided constructive reviews that improved the quality and clarity of this manuscript.

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Received: 2015-12-18
Accepted: 2016-5-25
Published Online: 2016-9-30
Published in Print: 2016-10-1

© 2016 by Walter de Gruyter Berlin/Boston

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https://doi.org/10.2138/am-2016-5692
Keywords for this article
Hyperspectral; reflectance; spectroscopy; rare earth elements; REE; xenotime; monazite; britholite

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  1. Research Article
  2. Temporal histories of Cordilleran continental arcs: testing models for magmatic episodicity
  3. Chemistry and Mineralogy of Earth’s Mantle
  4. Graphite-diamond relations in mantle rocks: Evidence from an eclogitic xenolith from the Udachnaya kimberlite (Siberian Craton)
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  11. Special collection: mechanisms, rates, and timescales of geochemical transport processes in the crust and mantle
  12. Fe-Mg interdiffusion in orthopyroxene
  13. Special Collection: Rates and Depths of Magma Ascent on Earth
  14. Error sources in single-clinopyroxene thermobarometry and a mantle geotherm for the Novinka kimberlite, Yakutia
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