Original paper
The nontronite-saponite series: An experimental approach
Grauby, Olivier; Petit, Sabine; Decarreau, Alain; Baronnet, Alain
European Journal of Mineralogy Volume 6 Number 1 (1994), p. 99 - 112
49 references
published: Feb 3, 1994
manuscript accepted: Oct 11, 1993
manuscript received: Nov 30, 1992
DOI: 10.1127/ejm/6/1/0099
Abstract
Abstract The study of the octahedral Fe-Mg substitution in smectites was conducted using clay synthesis at 200°C. Mossbauer data revealed that only ferric iron occurs in synthesized smectites. The studied series is then obviously heterovalent. All synthesized clays were tetrahedrally charged leading to structural formulae varying between nontronite and saponite end-members. According to XRD data, the b parameter increases continuously with Mg-contents, following a Vegard's law. AEM chemical analyses of isolated clay particles show a continuous evolution between the two end-members. However, IR data provide evidence for the segregation of octahedral cations in local dioctahedral and trioctahedral arrangements. The series is then a true continuous solid solution from nontronites to saponites, with differentiated octahedral clusters
Keywords
synthesis • solid solution • nontronite • saponite • ditrioctahedral lattice • spectroscopic methods