The Structural Relation Between Svetlozarite and Dachiardite

L. R. Gellens*, G. D. Price and J. V. Smith
Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois, USA 60637
*Present address: Centrum voor Oppervlakteschei-kunde en Colloidale Scheikunde, Katholieke Universiteit, Leuven, Belgium.

Abstract: Svetlozarite, previously described as a new member of the mordenite group of zeolites, is re-interpreted as a multiply twinned and highly faulted dachiardite. X-ray diffraction study and transmission electron microscopy revealed (001) twins and (100) stacking faults. The former are attributed at least mainly to the insertion of a b glide plane between dachiardite sheets at each twin interface, which preserves the 5-ring linkages between the sheets. The latter are associated with loss of the C face-centring relation, and are attributed to replacement of shared 5-rings by linked 4-rings in the dachiardite sheets. Further study is needed to determine whether the structural faults in the dachiardite structures are chemically controlled.

Mineralogical Magazine; 1982 v. 45; no. 337; p. 157-161; DOI: 10.1180/minmag.1982.045.337.18
© 1982, The Mineralogical Society
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