Structural Studies of Nontronites with Different Iron Contents by 57Fe Mössbauer Spectroscopy

C. M. Cardile and J. H. Johnston
Chemistry Department, Victoria University of Wellington Private Bag, Wellington, New Zealand

Abstract: The 57Fe Mössbauer spectra of a series of untreated and Ca-saturated nontronites showed a predominant Fe3+ resonance which was computer-fitted with two Fe3+ doublets defining iron in non-equivalent cis-FeO4(OH)2 octahedral sites. In most spectra a doublet indicating tetrahedral Fe3+ was fitted and in one untreated sample a doublet indicating interlayer Fe3+ was identified. In a further untreated sample the interlayer iron was present as Fe2+. Upon Ca-saturation the interlayer iron was displaced. It also appears that the interlayer iron was present in at least two different interlayer sites. From the computer-fitted data it was clear that the interlayer cations have a significant effect on the Mössbauer resonances of iron in the two non-equivalent cis-octahedral and the tetrahedral sites of nontronite.

Key Words: Interlayer cation • Iron • Mössbauer spectroscopy • Nontronite • Structural sites

Clays and Clay Minerals; August 1985 v. 33; no. 4; p. 295-300; DOI: 10.1346/CCMN.1985.0330404
© 1985, The Clay Minerals Society
Clay Minerals Society (www.clays.org)