Igneous petrology is the study of melts (magma) and the rocks that crystallize from such melts, encompassing an understanding of the processes involved in melting and subsequent rise, evolution, crystallization, and eruption or emplacement of the eventual rocks. Origin by crystallization from a melt seems a simple enough criterion for considering a rock to be igneous.

Petrology, from the Greek words petra , meaning rock, and logos, meaning knowledge, is the study of rocks and the conditions in which they form. It includes igneous, metamorphic, and sedimentary petrology.

Processes involved in the development of igneous and metamorphic rocks involve some combination of crystal growth, solution, movement and deformation, which is expressed as changes in texture (microstructure). Recent advances in the quantification of aspects of crystalline rock textures, such as crystal size, shape, orientation and position, have opened new avenues of research that extend and complement the more dominant chemical and isotopic studies.

Igneous and metamorphic petrology in the last decades of the twentieth century exploded into a broad, multifaceted, increasingly quantitative science. Advances in physical and field petrology and geochemistry have forever changed our thinking about the origin and evolution of magmas, their dynamic behavior, and the way in which they are intruded and explosively extruded. Developments in geochronology, quantitative evaluation of the role of heat and fluid transfer in crustal rocks, and new field discoveries have impacted our understanding of the evolution of metamorphic systems and their dynamic interaction with tectonic processes. Geophysics and mineral physics have provided new insights into the nature of the convecting mantle and its role as a giant heat engine driving magmatic and metamorphic processes. New tools of all kinds allow new ways of gathering petrologic data, while phenomenal developments in computers and computer software permit data to be stored, processed, and modeled in ways unimaginable as recently as a couple of decades ago.

This book is about metamorphic rocks: the processes involved in their formation and the reasons why they occur at particular places on the continents. It has been written to serve as an elementary text on the subjects of metamorphism and mountain building for non-specialist students of geology. It will be equally useful where geology is either the main or subsidiary subject and could be used by students intending to advance further in geology (the list of advanced texts in the further reading section would be more appropriate to such students). My intention in writing this book has been to try to dispel the notion that metamorphism comprises the 'haunted wing' of geology. Admittedly, there are rather a large number of technical terms in the book, but I hope that after working through it you will not find metamorphism an unduly difficult or obscure aspect of geology. Throughout, I have emphasised the strong links between mountain building, plate tectonics and metamorphic processes

The ever increasing amount of data on crystal arrangement in igneous and metamorphic rocks, alloys and ceramics, shows that the microtextures of these materials result from sequences of crystal growth and resorption. Metallurgists have become knowledgeable in the interpretation of textures and can make or modify textures of alloys in order to obtain specifjc responses to traction, distortion, etc. The modifications in texture can be reproduced or changed as often as desired. By analogy, it is probable that the microtextures observed in rocks may result from the same processes that govern similar textures in manufactured products. <...>

Metamorph;c processes have been taking place on a massive scale throughout the Earth's history, and have affected the bulk of the rocks now present in the crust. Despite this, they are not as well understood as sedimentary or volcanic processes, because metamorphism can scarcely ever be observed directly, and the study of metamorphic rocks is instead based on observation, inference and logic, founded in relatively simplistic experimental studies and the basic principles of chemistry and physics

The second edition of Principles of Igneous and Metamorphic Petrology follows the same general approach as the first edition. The book is designed to introduce igneous and metamorphic petrology to those who have completed introductory college-level courses in physics, chemistry, and calculus. Its emphasis is on principles and understanding rather than on facts and memorization. With this approach, it is hoped that students will not only gain a sound understanding of petrology but will develop skills that can be applied to the analysis of problems in many other fields of Earth Science. <...>

This text is designed for use in advanced undergraduate or early graduate courses in igneous and metamorphic petrology. The book is extensive enough to be used in separate igneous and metamorphic courses, but I use it for a one-semester combined course by selecting from the available chapters. The nature of geological investi-gations has largely shaped the approach that I follow.

Petrography of igneous end Metamorphic Rxks is designed for students taking their first course in petrography. It combines, in a single book, a compilation of the optica) properties of the common rock-forming m nerals. descriptions of the textures and structures of igneous and metamorphic rocks, and a treatment of the classification of these rocks. The book deals with the description of rocks, not their origins. The coverage is not exhaustive and is limited to what students are likely to encounter and need to know in an introductory petrography course. The material is organized so as to make it as rapidly accessible as possible, for those who have not previously had a course in optical mineralogy. Chapter 2 briefly introduces this subject.