Abstract
The orientations of the hydoxyl groups in the minerals kaolinite, dickite and nacrite have been determined by an iterative process based on the minimization of the total electrostatic energy of the respective crystal structures. The hydroxyl shared by the tetrahedral and octahedral sheets is directed toward the empty octahedral sites in all three structures. The remaining three hydroxyls which form the surface of the octahedral sheet are nearly normal to the layer in dickite, two are nearly normal, and one is inclined at an angle of 38° to the kaolin layer in nacrite, and in kaolinite two are nearly normal and the third is inclined at an angle of 14° to the layer. In each mineral, the hydroxyls forming the surface of the octahedral sheet are directed away from the kaolin layer.
