Stacking faults with 180° layer rotation in celadonite, an fe- and mg-rich dioctahedral mica
Toshihiro, Kogure (The University of Tokyo. Department of Earth and Planetary Science)
Jun, Kameda (The University of Tokyo. Department of Earth and Planetary Science)
Drits, Victor A. (Geological Institute of the Russian Academy of Sciences)

Data:	2008
Resum:	Stacking disorder in celadonite, a dioctahedral mica with Fe and Mg as major octahedral cations and which generally adopts the 1M stacking sequence, was investigated mainly by using transmission electron microscopy (TEM). The selected-area electron diffraction patterns with 0kl reflections along the [100] beam direction correspond to the 1M stacking but those along the [110], [11-0], [010], [310], and [31-0] directions are frequently streaked along the [001]* direction or contain extra spots from twinned domains. Three-dimensional stacking analyses using sets of two high-resolution TEM images along different directions of the same area of one crystal indicate that all stacking faults involve only 180° layer rotations. These stacking faults produce greater peaks of 0kl reflections than expected in powder X-ray diffraction (XRD) patterns. Simulation of the XRD patterns indicated that 180° layer rotations occur at >10% of total interlayer regions in one celadonite specimen. The interlayer region of celadonite is characterized by a near-zero ditrigonal rotation angle, a small surface corrugation of the basal oxygen plane, and a small amount of Al substitution in the tetrahedral sheets. These features suggest that there is no preference for any of the six stacking angles around the interlayer region. The abundance of 180° layer rotation rather than G60° and G120° in the present specimens may be related to their ribbon-like morphologies elongated along the a axis.
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Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Celadonite ; Electron Microscopy ; Mica ; Polytype ; Stacking Faults ; X-ray Diffraction
Publicat a:	Clays and Clay Minerals, Vol. 56, Núm. 6 (2008) , p. 612-621, ISSN 1552-8367

DOI: 10.1346/CCMN.2008.0560602

10 p, 1.1 MB  Accés restringit a la UAB

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