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Zirconolites from Sri Lanka, South Africa and Brazil

Published online by Cambridge University Press:  15 February 2011

Rodney C. Ewing ,
Richard F. Haaker ,
Thomas J. Headley  and
Paul F. Hlava
Rodney C. Ewing
Affiliation:
Department of Geology, University of New Mexico, Albuquerque, NM 87131
Richard F. Haaker
Affiliation:
Department of Geology, University of New Mexico, Albuquerque, NM 87131
Thomas J. Headley
Affiliation:
Sandia National Laboratories*, Albuquerque, NM 87185
Paul F. Hlava
Affiliation:
Sandia National Laboratories*, Albuquerque, NM 87185
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Abstract

Zirconolites, CaZrTi2O7, from Sri Lanka and Pala Bora, South Africa, and a calzirtite, CaZr3 TiO9, from Jacupiranga, Brazil, were examined using the electron microprobe, x-ray diffraction (annealing study), transmission electron microscopy, scanning electron microscopy and optical microscopy. The x-ray data indicate that all three zirconolites are metamict. Both Sri Lanka zirconolites are amorphous to the limits of resolution of the electron microscope (֮10 A). The Pala Bora zirconolite is largely amorphous but contains isolated domains (50–200 A) of crystalline material which may be the result of post—metamict recrystallization and alteration. The only other significant evidence for chemical alteration was the lower Th concentration (1–2 weight percent) and slightly lower analytic totals for the rims of the Sri Lanka zirconolites. Upon annealing at 1130°C for 5 hours, all three zirconolites recrystallized as microcrystalline aggregates. Refined unit cell parameters and volumes are consistent with published data for synthetic zirconolites. Both Sri Lanka zirconolites contain microvoids, spherical in shape, and 200 Angstroms to 2 microns in size. This porosity may be the result of helium accumulation arising from the decay of U and Th. The calzirtite was highly crystalline, exhibited no porosity, and was unchanged by the annealing treatment.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 6: Symposium D – Scientific Basis for Nuclear Waste Management IV , 1981 , 249
Copyright
Copyright © Materials Research Society 1982

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References

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