Clays and Clay Minerals, Vol. 55, No. 4, 380–388, 2007.
Loading...
Authors
Meunier, Alain
Issue Date
2007
Type
Article
Language
Keywords
Periodicals , Geology , Adsorption , Aluminum , Hydroxy-interlayered , Polymerization , Soil Clays
Alternative Title
Soil Hydroxy-interlayered Minerals: A Re-interpretation Of Their Crystallochemical Properties
Abstract
Hydroxy-interlayered minerals (HIMs) are typical of moderately acidic soils. Barnhisel and Bertsch (1989) defined the hydroxy-interlayered clay minerals as a solid-solution series between smectite, vermiculite and pedogenic or aluminous chlorite end-members. Their experimental data for the relationship between the decrease in cation exchange capacity (CEC) and the amount of Al fixed in the interlayers of smectites and vermiculites is reinterpreted using calculated structural, chemical and X-ray diffraction (XRD) evidence. The adsorbed Al ions are in a 6-fold coordination state: [Al(OH)x(H2O)y](3-x)+ with x+y = 6. The polymerization process occurs before saturation of the exchange sites by Al ions. Some of the adsorbed Al ions form polynuclear cations keeping a constant positive charge. X-ray diffraction patterns of oriented preparations in the ethylene glycol-solvated state suggest that HIMs consist of randomly interstratified expandable and chlorite-like layers (17 and 14.2 A ˚ ). Chlorite-like layers result from the selective adsorption of Al complex ions in specific interlayer zones that behave similarly to Al-chlorite (donbassite-like) with incomplete (60%) ‘gibbsite-like’ sheets (chlorite60). Using this framework, HIM XRD patterns can be interpreted by comparison with calculated chlorite60-dismectite mixed-layer mineral patternss using the NEWMOD software.
Description
Clays and Clay Minerals, Vol. 55, No. 4, 380–388, 2007. Soil Hydroxy-interlayered Minerals: A Re-interpretation Of Their Crystallochemical Properties. Alain Meunier. DOI: 10.1346/CCMN.2007.0550406. Copyright © 2007, The Clay Minerals Society
Citation
Clays and Clay Minerals, Vol. 55, No. 4, 380–388, 2007.
Publisher
The Clay Minerals Society
License
Copyright © 2006-2018, The Clay Minerals Society