Polymorphism of the Micas and Diffuse X-Ray Scattering of Layer Silicate Lattices

THE first significant work on the structures of the micas was that of Maugin1, who measured the units of structure and discussed types of isomorphous replacements. Pauling2, on the basis of his co-ordination theory, proposed general structures that were shown by Jackson and West3 to be correct in some detail for muscovite. Maugin noted that the lattice dimension along the c axis of a biotite crystal was apparently one half that of muscovite, and he further observed diffuse scattering of X-rays from several crystal zones.