Subvolume 27I compiles the magnetic properties of silicates and phosphates; the present subvolume 27I5 deals with phyllosilicates. Subvolume 27I5 is presented in two parts: part 27I5a discusses gillespites, apophyllites, natrolites, micas, smectites and related silicates. The book discusses crystal structure and gives atomic positions. Beyond magnetic properties, the book reviews results of neutron diffraction studies, nuclear gamma resonance, nuclear magnetic resonance, X-ray absorption spectroscopy, transport properties, dielectric and optical data.