Phase Decomposition upon Alteration of Radiation-Damaged Monazite–(Ce) from Moss, Østfold, Norway

Authors

  • Lutz Nasdala Institut für Mineralogie und Kristallographie, Universität Wien, Althanstrasse 14, A–1090 Wien, Austria
  • Katja Ruschel Institut für Mineralogie und Kristallographie, Universität Wien, Althanstrasse 14, A–1090 Wien, Austria
  • Dieter Rhede Helmholtz-Zentrum Potsdam, Deutsches GeoForschungsZentrum, Telegrafenberg, D–14473 Potsdam, Germany
  • Richard Wirth Helmholtz-Zentrum Potsdam, Deutsches GeoForschungsZentrum, Telegrafenberg, D–14473 Potsdam, Germany
  • Ljuba Kerschhofer-Wallner BWI Informationstechnik GmbH, Balanstr. 73, D–81541 München, Germany
  • Allen K. Kennedy Department of Applied Physics, Curtin University of Technology, Building 301, Kent Street, Bentley, WA 6102, Australia
  • Peter D. Kinny Department of Applied Geology, Curtin University of Technology, Building 312, Kent Street, Bentley, WA 6102, Australia
  • Friedrich Finger Fachbereich Materialforschung und Physik, Universität Salzburg, Hellbrunnerstrasse 34, A–5020 Salzburg, Austria
  • Nora Groschopf Institut für Geowissenschaften, Universität Mainz, Johann-Joachim-Becher-Weg 21, D–55099 Mainz, Germany

DOI:

https://doi.org/10.2533/chimia.2010.705

Keywords:

Chemical alteration, Monazite-(ce), Radiation damage, Thorium silicate

Abstract

The internal textures of crystals of moderately radiation-damaged monazite–(Ce) from Moss, Norway, indicate heavy, secondary chemical alteration. In fact, the cm-sized specimens are no longer mono-mineral monazite but rather a composite consisting of monazite–(Ce) and apatite pervaded by several generations of fractures filled with sulphides and a phase rich in Th, Y, and Si. This composite is virtually a 'pseudomorph' after primary euhedral monazite crystals whose faces are still well preserved. The chemical alteration has resulted in major reworking and decomposition of the primary crystals, with potentially uncontrolled elemental changes, including extensive release of Th from the primary monazite and local redeposition of radionuclides in fracture fillings. This seems to question the general alteration-resistance of orthophosphate phases in a low-temperature, 'wet' environment, and hence their suitability as potential host ceramics for the long-term immobilisation of radioactive waste.

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Published

2010-10-29

Issue

Section

Scientific Articles

How to Cite

[1]
L. Nasdala, K. Ruschel, D. Rhede, R. Wirth, L. Kerschhofer-Wallner, A. K. Kennedy, P. D. Kinny, F. Finger, N. Groschopf, Chimia 2010, 64, 705, DOI: 10.2533/chimia.2010.705.