Journal of the Royal Society of New Zealand abstracts
Structural studies of New Zealand pounamu using Mössbauer
spectroscopy and electron paramagnetic resonance
W. Craighead Tennant1*, Rodney F. C. Claridge1,
Catherine A. McCammon2, Alex I. Smirnov3, and
Russell J. Beck4
1Chemistry Department,
University of Canterbury, Private Bag 4800, Christchurch 8020, New
Zealand. craig.tennant@canterbury.ac.nz
2Bayerisches
Geoinstitut, Universität Bayreuth, D-95440 Bayreuth,
Germany.
3Department
of Chemistry, North Carolina State University, Campus Box 8204,
Raleigh, NC 27695, USA.
427
Chelmsford Street, Invercargill, New Zealand.
Abstract We report Mössbauer spectroscopy and
electron paramagnetic resonance spectroscopy (EPR) studies of a number
of New Zealand minerals that can be classified under the non-specific
names “pounamu” or “greenstone”. Mössbauer measurements allowed
the distribution of iron in its +2 and +3 oxidation states to be
assigned to the M1 to M4 sites of the constituent minerals,
tremolite-actinolite in the case of nephrite jades. EPR at two
frequencies, 9.4 GHz (X-band) and 94.1 GHz (W-band), allowed the
determination of the distribution of Mn2+ in these sites.
The results are apparently contrary to the usual assignments made for
the parent minerals tremolite and actinolite. In two cases, one a
nephrite jade and the other a serpentine, significant quantities of
magnetically ordered minerals chalcopyrite and magnetite were
identified by Mössbauer spectroscopy. These minerals could not be
found in the X-ray diffraction patterns of the same minerals leading to
the conclusion that they are very finely divided in the samples
studied.
Keywords pounamu; greenstone; Mössbauer
spectroscopy; electron paramagnetic resonance
This paper continues a study initiated by the late Professor
Cuthbert J. Wilkins. It is to his memory that the paper is dedicated.
R05003 Received 21 January 2005; accepted 21 April 2005; Online
publication date 6 December 2005
Journal of the Royal Society of New Zealand
Volume 35, Number 4, December, 2005, pp 385–398
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