A Mössbauer and I.R. Spectroscopic Study of the Structure of Nontronite

B. A. Goodman, J. D. Russell, A. R. Fraser and F. W. D. Woodhams
The Macaulay Institute for Soil Research, Craigiebuckler, Aberdeen AB9 2QJ, U.K.
Department of Natural Philosophy, University of Aberdeen, Aberdeen, U.K.

Abstract: Mössbauer and i.r. spectra of a series of nontronites show that Fe3+ and Al3+ are distributed between tetrahedral and octahedral sites. The Mössbauer results have reaffirmed the occupation by Fe3+ of octahedral sites at which these ions are coordinated to pairs of OH groups in both cis and trans configurations. The distribution of Fe3+ between these two sites varies considerably but in all of the nontronites some Fe3+ occurs in the trans site in contrast to the all cis occupancy of the centro-symmetric structure proposed by Mering and Oberlin (1967). In one of the nontronites the distribution of Fe3+ between these two sites approaches that in the ideal non-centrosymmetric structure proposed for montmorillonite.

Clays and Clay Minerals; April 1976 v. 24; no. 2; p. 53-59; DOI: 10.1346/CCMN.1976.0240201
© 1976, The Clay Minerals Society
Clay Minerals Society (www.clays.org)