Volume 56 of the Reviews in Mineralogy and Geochemistry reviews the current state of knowledge
on the epidote minerals with special emphasis on the advances that were made since the
comprehensive review of Deer et al. (1986). In the Introduction we review the structure
optical data and crystal chemistry of this mineral group all of which form the basis for
understanding much of the following material in the volume. In addition we provide some
information on special topics such as morphology and growth deformation behavior and
gemology. Thermodynamic properties (Chapter 2 Gottschalk) the spectroscopy of the epidote
minerals (Chapter 3 Liebscher) and a review of the experimental studies (Chapter 4 Poli and
Schmidt) constitute the first section of chapters. These fields are closely related and all
three chapters show the significant progress over the last years but that some of the critical
questions such as the problem of miscibility and miscibility gaps are still not completely
solved. This section concludes with a review of fluid inclusion studies (Chapter 5 Klemd) a
topic that turned out to be of large interest for petrogenetic interpretation and leads to the
description of natural epidote occurrences in the second section of the book. These following
chapters review the geological environments of the epdiote minerals from low temperature in
geothermal fields (Chapter 6 Bird and Spieler) to common metamorphic rocks (Chapter 7 Grapes
and Hoskin) and to high- and ultrahigh pressure (Chapter 8 Enami Liou and Mattinson) and the
magmatic regime (Chapter 9 Schmidt and Poli). Allanite (Chapter 10 Gieré and Sorensen) and
piemontite (Chapter 11 Bonazzi and Menchetti) on which a large amount of information is now
available are reviewed in separate chapters. Finally trace element (Chapter 12 Frei
Liebscher Franz and Dulski) and isotopic studies both stable and radiogenic isotopes (Chapter
13 Morrison) are considered. We found it unavoidable that there is some overlap between
individual chapters. This is an inherited problem in a mineral group such as the epidote
minerals which forms intensive solid solutions between the major components of rock forming
minerals as well as with trace elements.
