Abstract Nearly 40 papers involving structural refinements of phyllosilicate minerals, including those of 30 micas, have appeared during 1981–1985, plus a number of other papers involving structural information obtained from infrared, nuclear magnetic resonance, Mössbauer, and Raman spectra. Consequently, our knowledge of the geometry, energetics, crystal chemistry, and long-range cation order-disorder relationships in all the clay mineral groups has advanced enormously during this period. In addition to the explosion of information in the mica group, the other very important advance has been the precise location of the H + protons of the OH groups for examples of all the clay mineral groups, except smectite and sepiolite-palygorskite, either by detailed X-ray or neutron diffraction study. Information is just starting to emerge on local or short-range cation ordering in clay minerals.