Interrelated Features of Structure and Stacking of Kaolin Mineral Layers

B. B. Zvyagin1 and V. A. Drits2
1 Institute of Ore Mineralogy (IGEM), Russian Academy of Sciences Staromonetny 35, 109017 Moscow, Russia
2 Geological Institute (GIN), Russian Academy of Sciences Pyzhevsky 7, 109017 Moscow, Russia

Abstract: Layer stackings in the ideal and real kaolinite structures are considered in terms of layer orientations i = 1, 2, … 6, intra- and interlayer displacements of adjacent 0- and T-sheets, si and tk, distortions of these displacements δ1 and δ2, deviations of unit cell parameters ηi = b2i/a2i − 3, εi = γi − π/2, and normal projections cn of the axis vector c on the ab plane.

The ideal monoclinic angle of dickite (cnx = −⅓) and the deviation α - π/2 ≠ 0 for kaolinite are explained by combinations of the δ1 and δ2 values in the sequence of symbols si and tk defining the corresponding structures. Twenty stacking variants in the 3 successive layers of the kaolinite structure are derived, incorporating layer orientations of the same parity, displacements t+, − = [0, ± ⅓] and reflection operations in planes normal to the axis b3. Two deformation mechanisms are proposed for the accommodation of successive layer unit cells adjusting either angular or linear parameters at the agreement of either linear or angular parameters corresponding.

Key Words: Dickite • Halloysite • Kaolinite • Polytypism • Stacking faults

Clays and Clay Minerals; June 1996 v. 44; no. 3; p. 297-303; DOI: 10.1346/CCMN.1996.0440301
© 1996, The Clay Minerals Society
Clay Minerals Society (www.clays.org)