One to one clay mineral structure

The simplest arrangement of tetrahedral and octahedral sheets is a 1 : 1 layering, shown in Fig. 4.8 and developed more fully in Fig. 4.9. These 1: 1 minerals comprise the serpentine-kaolin group of clay minerals, of which the mineral kaolin-ite is probably the best known (Fig. 4.10). In kaolinite, the 1: 1 packages are held together by hydrogen bonds (Box 4.1), which bridge between OH groups of the upper layer of the octahedral sheet and the basal oxygens of the overlying tetrahedral sheet. The hydrogen bonds are strong enough to hold the 1 : 1 units together, preventing cations getting between layers (interlayer sites). Isomor-phous substitution (Box 4.6) in kaolinite is negligible.

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