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Transmission electron microscopy of a refractory inclusion from the Allende meteorite: Anatomy of a pyroxene
Author(s) -
Doukhan N.,
Doukhan J. C.,
Poirier J. P.
Publication year - 1991
Publication title -
meteoritics
Language(s) - English
Resource type - Journals
eISSN - 1945-5100
pISSN - 0026-1114
DOI - 10.1111/j.1945-5100.1991.tb01025.x
Subject(s) - allende meteorite , pyroxene , spinel , crystallization , transmission electron microscopy , dislocation , geology , mineralogy , meteorite , crystal (programming language) , materials science , crystallography , olivine , chondrite , metallurgy , chemistry , astrobiology , physics , nanotechnology , organic chemistry , computer science , programming language
— A crystal of clinopyroxene from the coarse‐grained refractory inclusion Egg 6 of the Allende meteorite has been studied in detail by transmission electron microscopy. The pyroxene crystal contains euhedral, dislocation‐free inclusions of pure spinel MgAl 2 O 4 , without any topotactic relation to the host. Extensive dislocation walls at equilibrium, characteristic of high‐temperature anneal, are present in the crystal. Alteration products are occasionally observed at the spinel‐pyroxene interface close to regions where dislocation walls decorated with bubbles (or voids) are present. The bubbles, often in the shape of tubes along the dislocation lines, are thought to be due to the precipitation of a fluid migrating along the dislocations. The observations are compatible with crystallization of the refractory inclusions from the melt and with the existence of a later stage of metasomatism.