Volume 13 of Reviews in Mineralogy attempts to gather together much of our knowledge of micas, the most abundant phyllosilicate, and to indicate promising areas of future research. Chapters 1-3 lay the foundations of the classification, structures, and crystal chemistry of micas. Chapter 4 treats bonding and electrostatic modeling of micas. Chapters 5 and 6 cover spectroscopic and optical properties. Chapters 7-13, the bulk of the volume, are devoted to geochemistry and petrology. These include phase equilibria and the occurrences, chemistry, and petrology of micas in igneous, metamorphic, and sedimentary rocks, pegmatites, and certain ore deposits. Some treatments are exhaustive. All are at the forefront of our present knowledge, and indicate clearly the practical applications'of the study of micas to ascertaining various parameters of origin and crystallization history, as well as the many problems that still exist. The aim of this type of treatment is to provide a reference volume for teachers and students and to enable researchers to pick more easily those directions and problems for which future research is most needed or is apt to be most productive or most challenging.

This book completes Professor Shrock's full-scale history of MIT's Geology Department.

Developments in Petrology, 6: Trondhjemites, Dacites, and Related Rocks focuses on the geology, geochemistry, and petrology of several kinds of trondhjemites, dacites, and genetically related rocks. The selection first elaborates on the definition, environment, and hypotheses of origin of trondhjemite; a review of the mineralogy and chemistry of tertiary-recent dacitic, latitic, rhyolitic, and related salic volcanic rocks; and some trace elements in trondhjemites and their implications to magma genesis and paleotectonic setting. Discussions focus on tectonic environments and trace element patterns, selection and reliability of trace elements, interrelationships between mineralogy and chemistry, and regional variations of dacitic and rhyolitic magmas. The publication then tackles strontium isotope geochemistry of late Archean to late Cretaceous tonalites and trondhjemites; Archean gray gneisses and the origin of the continental crust in West Greenland; and metamorphic development of early Archean tonalitic and trondhjemitic gneisses in Saglek Area, Labrador. The book examines the petrology, geochemistry, and origin of the Sparta quartz dioritetrondhjemite complex; reconnaissance geochemistry of Devonian island-arc volcanic and intrusive rocks in West Shasta District, California; and origin of the Twillingate trondhjemite in North-Central Newfoundland. The selection is highly recommended for geologists and geochemists wanting to explore trondhjemites, dacites, and genetically related rocks.