Clays and Clay Minerals, Vol. 56, No. 1, 10–22, 2008.
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Authors
Gates, Will P.
Issue Date
2008
Type
Article
Language
Keywords
Periodicals , Geology , Cation Mass , Cation Pairs , Infrared Spectroscopy , Octahedral , Smectite Chemistry , Valence Sum
Alternative Title
Cation Mass-valence Sum (cm-vs) Approach To Assigning Oh-bending Bands In Dioctahedral Smectites
Abstract
The assignments ofOH-bending bands in the infrared (IR) spectra ofdioctahe dral smectites (montmorillonites, ferruginous smectites, and nontronites) have been revisited using a cation mass-valence sum (CM-VS) approach to quantify octahedral cation occupancy. The CM-VS approach enabled prediction ofOH-bendin g band positions (in wavenumbers) related to OH-sharing octahedral cation pairs that had valence sums of4 and 5, and cation masses associated with Fe(II) and Mg. Application ofrules for the relationship enabled determination ofthe location ofOH-sharing octahedral cation pairs containing Mg and Fe(II) for which previous assignments have been considered controversial, e.g. Fe(III)Mg-OH and MgMg-OH, or for which assignments have been missing due to lack of spectroscopic evidence, e.g. AlFe(II)-OH, Fe(III)Fe(II)-OH, Fe(II)Mg-OH, and Fe(II)Fe(II)-OH. Examples ofthe se bands from several natural ferruginous smectites and nontronites are discussed. Quantification of IR spectra was used to develop a better understanding ofthe octahedral cation occupancy ofthis important class ofFe(III)- enriched smectites. While Fe(II) contents may be somewhat overestimated by the IR technique, those for four of the six ferruginous smectites studied here agree well with data from Mo¨ssbauer spectroscopy.
Description
Clays and Clay Minerals, Vol. 56, No. 1, 10–22, 2008. Cation Mass-valence Sum (cm-vs) Approach To Assigning Oh-bending Bands In Dioctahedral Smectites. Will P. Gates. DOI: 10.1346/CCMN.2008.0560102. Copyright © 2008, The Clay Minerals Society.
Citation
Clays and Clay Minerals, Vol. 56, No. 1, 10–22, 2008.
Publisher
The Clay Minerals Society
License
Copyright © 2006-2018, The Clay Minerals Society