Mössbauer Spectroscopic Identification of Iron Oxides in Nontronite from Hohen Hagen, Federal Republic of Germany

Paul R. Lear1, Peter Komadel2 and Joseph W. Stucki
Department of Agronomy, University of Illinois, Urbana, Illinois 61801
1 Present address: Department of Chemistry, Michigan State University, East Lansing, Michigan 48824.
2 Permanent address: Institute of Inorganic Chemistry, Center of Chemical Research, Slovak Academy of Sciences, 84236 Bratislava, Czechoslovakia.

Abstract: Iron impurities in the Hohen Hagen nontronite (NG-1) were identified as maghemite and goethite. The phase identified as maghemite was magnetically ordered at both room temperature and 87 K, with hyperfine magnetic fields of 48.6 and 50.7 tesla, respectively. Due to the magnetic properties of this phase, it was easily separated from aqueous dispersions of the clay using a hand magnet. X-ray powder diffraction analysis revealed maghemite, quartz, and phyllosilicate in the magnetically separated phase. The impurity identified as goethite remained in the non-magnetic <2-µm fraction of the clay, displayed magnetic order only at 87 K (47.44 tesla hyperfine field), and accounted for about 8% of the total area of the Mössbauer spectrum.

Key Words: Goethite • Iron • Maghemite • Magnetic properties • Mössbauer spectroscopy • Nontronite

Clays and Clay Minerals; August 1988 v. 36; no. 4; p. 376-378; DOI: 10.1346/CCMN.1988.0360414
© 1988, The Clay Minerals Society
Clay Minerals Society (www.clays.org)