minerals Article The Nature of Laponite: Pure Hectorite or a Mixture of Different Trioctahedral Phases? George E. Christidis 1,*, Carlos Aldana 2, Georgios D. Chryssikos 3, Vassilis Gionis 3, Hussein Kalo 4 ID , Matthias Stöter 5, Josef Breu 5 and Jean-Louis Robert 6,† 1 School of Mineral Resources Engineering, Technical University of Crete, 73100 Chania, Greece 2 Institut des Sciences de la Terre d’Orléans, CNRS, 1A Rue de la Ferollerie, 45100 Orléans, France;
[email protected] 3 Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vass. Constantinou Ave., 11635 Athens, Greece;
[email protected] (G.D.C.);
[email protected] (V.G.) 4 BYK-Chemie GmbH, Stadtwaldstrasse 44, 85368 Moosburg, Germany;
[email protected] 5 Lehrstuhl für Anorganische Chimie I, Universität Bayreuth, 95440 Bayreuth, Germany;
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[email protected] (J.B.) 6 IMPMC, Sorbonne Universités, UMR 7590, UPMC, CNRS, MNHN, IRD, 4 Place Jussieu, CEDEX 05, 75231 Paris, France;
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[email protected] † Deceased. Received: 30 June 2018; Accepted: 24 July 2018; Published: 26 July 2018 Abstract: A series of laponites and synthetic OH- and fluorinated hectorites prepared from hydrothermal and melting experiments at both industrial and laboratory scale were examined with XRD and FTIR (MIR and NIR) to determine their mineralogical composition and possible compositional heterogeneity. The end materials contained both Li- and Na-bearing phases. The industrial hydrothermal OH-smectites prepared at low temperatures consist of random mixed layer hectorite-stevensite-kerolite with about 40–50% hectorite layers, the remaining being stevensite and kerolite at roughly equal proportions.