Infrared Studies of Ni-Bearing Clay Minerals of the Kerolite-Pimelite Series

P. Gerard1 and A. J. Herbillon2
1 Ministère des Affaires Economiques, Laboratoire Central, rue de la Senne 17a, B-1000 Bruxelles, Belgium
2 Section de Physico-chimie Minérale du Musée Royal de l'Afrique Centrale and Université Catholique de Louvain, Place Croix du Sud 1, B-1348 Louvain-la-Neuve, Belgium

Abstract: Two kerolite and one garnierite samples were subjected to progressive heat treatments prior to their examination by infrared spectroscopy (IR) in the 1200–600-cm−1 and 3800–3000-cm−1 regions. The heat treatment of the garnierite (a mixture of nepouite and pimelite) selectively dehydroxylated the nepouite thus allowing an examination to be made of the OH-vibration bands due to the pimelite. Both the relative intensities of the 710–670-cm−1 doublet and of the different OH-stretching bands indicated the Ni content of this pimelite to be about 70%. The heat treatments did not modify the 1200–600-cm−1 region of the spectra of kerolites but caused a noticeable sharpening in the OH-stretching region. The relative intensities of the structural OH-stretching bands of dehydrated kerolites showed that they differ from Ni-talcs of similar composition in the distribution of Ni and Mg in the octahedral sites. These cations are randomly distributed in Ni-talc but are mainly segregated into Mg and Ni domains in kerolite. Changes in sharpness, intensity, and position of the structural OH-stretching bands of the kerolites as temperature increases and dehydration progresses are similar to those undergone by Mg- or Li-saturated trioctahedral smectites, Also thermal analysis curves of these minerals show similarities with those of Mg- and Ni-saturated smectites, and suggest that in kerolites too, the hydration water is associated with interlayer (though non-exchangeable) Ni and/or Mg cations.

Key Words: Dehydroxylation • Garnierite • Infrared spectroscopy • Kerolite • Nickel • Pimelite

Clays and Clay Minerals; April 1983 v. 31; no. 2; p. 143-151; DOI: 10.1346/CCMN.1983.0310209
© 1983, The Clay Minerals Society
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