Halloysite -A critical assessment

Water enters the interlayer space in halloysite to minimize cation-cation Coulomb repulsion between adjacent layer surfaces and to coordinate exchangeable cations postulated as present to compensate for Al(IV). The layers roll into tubes due to lateral misfit between a larger tetrahedral sheet and a smaller octahedral sheet. Tetrahedral rotation, which compensates similar lateral misfit in most layer silicate structures, is blocked in halloysite by dynamic disorder of H-bonds from H₂O molecules so basal oxygens cannot all rotate in the same direction and/or insertion of "hole water" or exchangeable cations into ring openings. Halloysite differs from kaolinite in composition, layer stacking sequence, and ring configuration.Bailey Sturges W. Halloysite -A critical assessment. In: Proceedings of the 9th international Clay Conference, Strasbourg, 1989. Vol II : Surface chemistry. Structure and mixed layering of clays. Strasbourg : Institut de Géologie – Université Louis-Pasteur, 1990. pp. 89-98. (Sciences Géologiques. Mémoire, 86