Volume 13 of Reviews in Mineralogy presents much of our present-day knowledge of micas. Since
1984 was too much material available to attempt to cover all of the hydrous phyllosilicates in
one volume the micas were treated first because of their abundance in nature and the fact that
many detailed studies had been carried out on them. The serpentines kaolins smectites
chlorites etc. would have to wait their turn. Now four years later that tum has come. Hence
the peculiar nature of the title of this volume. We know less about the rest of the
phyllosilicates than we do about the micas primarily because many of them are of finer grain
sizes and lower crystallinities than most of the micas. As a result we have been unable to
determine as much detail regarding their structures crystal chemistries and origins. One
compensating factor that has helped greatly in the accumulation of knowledge about these
minerals is that some of them occur in large deposits that are of great economic value and thus
stimulate interest. For this reason considerable emphasis in this volume will be related to the
occurrence origin and petrology of the minerals.
