Abstract
The NMR spectra of 27Al and 23Na and the EPR spectra of Fe3+ and Mn2+ have been studied in a range of plagioclase feldspars, of intermediate composition. Many of these crystals have previously been investigated by TEM methods (McLaren and Marshall, 1974). The broad, central 27Al signals observed in labradorites have been interpreted in terms of an overall order/disorder of the Al/Si distribution. Spin Hamiltonian parameters have been determined for the Fe3+ spectra observed in labradorites and bytownites; these spectra were similar and yielded evidence of disordering of the Al/Si distribution. The severe limitations imposed by the variety of sites, the complex microstructures and the disordering, limit the structural information available from the resonance methods.
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Scala, C.M., Hutton, D.R. & McLaren, A.C. NMR and EPR studies of the chemically intermediate plagioclase feldspars. Phys. Chem. Minerals 3, 33–44 (1978). https://doi.org/10.1007/BF00357445
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DOI: https://doi.org/10.1007/BF00357445