Further Discussion of Framework Structures Built from Four- and Eight-Membered Rings

J. V. Smith
Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois 60637, U.S.A.

Summary: The classification of framework structures built from chains of four-membered rings of type UUDD is incomplete: there are two basic ways in which the chains can be cross-linked to form eight-membered rings. The first type of frame-work (already described) is extremely flexible, permitting the cavities to be either large or small; the second type is inflexible and the cavities are small. Feldspar belongs to the second type and had been incorrectly ascribed to the first type: paracelsian, harmotome, and gismondine had been correctly placed in the first group.

Mineralogical Magazine; March 1968 v. 36; no. 281; p. 640-642; DOI: 10.1180/minmag.1968.036.281.04
© 1968, The Mineralogical Society
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