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Photo-emission electron microscopy (PEEM) heating investigations of a natural amphibole sample

Published online by Cambridge University Press:  05 July 2018

J.-A. Wartho
J.-A. Wartho*
Affiliation:
Department of Earth Sciences, University of Leeds, Leeds, LS2 9JT, UK
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Abstract

PEEM allows ‘real-time’ observations to be made of solid-state transformations and other high-temperature processes taking place during vacuum-heating up to c. 2000°C The solid state transformations of an amphibole-rich hornblendite specimen have been observed in the temperature range of 750–1000°C (± 50°C Between c. 970–990°C a rapid change in orientation contrast was observed, indicating a structural rearrangement from an oxyhornblende crystal lattice to a clinopyroxene structure. This phase retains the original amphibole shape and texture (including two 120°C intersecting cleavage traces), but possesses a clinopyroxene crystal structure. At higher temperatures this phase is seen to decompose, forming iron oxides and other fine-grained products. PEEM has provided useful information on both the nature and rates of transformation of natural amphiboles which has proved invaluable in our understanding of the mineralogically-controlled mechanisms of argon release during 40Ar/39Ar dating of amphibole samples.

Keywords

Photo-emission electron microscopyvacuum-heatingamphibolessolid state transformations
Type
Mineralogy
Information
Mineralogical Magazine , Volume 59 , Issue 394 , March 1995 , pp. 121 - 127
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1995

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Footnotes

*

Present address: Department of Earth Sciences, Open University, Walton Hall, Milton Keynes, MK7 6AA. UK

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