Physical Properties And Thermodynamic Behaviour Of Minerals

The role played by earth sciences in the scientific community has changed considerably during this century. Since the revolutionary discoveries of global processes such as plate tectonics, there has been an increasing awareness of just how fundamental many of the mechanisms which dominate in these processes depend on the physical properties of the materials of which the earth is made. One of the prime objectives of mineral sciences is now to understand and predict these properties in a truly quantitative manner. The macroscopic properties which are of most immediate interest in this context fall within the conventional definitions of thermodynamics, magnetism, elasticity, dielectric susceptibilities, conductivity etc. These properties reflect the microscopic contributions, at an atomistic level, of harmonic and anharmonic lattice vibrations, ionic and electronic transport as well as a great variety of ordering and clustering phenomena. The advances made by solid state physicists and chemists in defining the underlying phenomena lnvolved in the thermal evolution of materials have stimulated major new research initiatives within the Earth Sciences. Earth Scientists have combined to form active groups within the wider community of solid state and materials scientists working towards a better understanding of those physical processes which govern not only the behaviour of simple model compounds but also that of complex materials like minerals. Concomitant with this change in direction has come an increasing awareness of the need to use the typical working tools of other disciplines.

The role played by earth sciences in the scientific community has changed considerably during this century. Since the revolutionary discoveries of global processes such as plate tectonics, there has been an increasing awareness of just how fundamental many of the mechanisms which dominate in these processes depend on the physical properties of the materials of which the earth is made. One of the prime objectives of mineral sciences is now to understand and predict these properties in a truly quantitative manner. The macroscopic properties which are of most immediate interest in this context fall within the conventional definitions of thermodynamics, magnetism, elasticity, dielectric susceptibilities, conductivity etc. These properties reflect the microscopic contributions, at an atomistic level, of harmonic and anharmonic lattice vibrations, ionic and electronic transport as well as a great variety of ordering and clustering phenomena. The advances made by solid state physicists and chemists in defining the underlying phenomena lnvolved in the thermal evolution of materials have stimulated major new research initiatives within the Earth Sciences. Earth Scientists have combined to form active groups within the wider community of solid state and materials scientists working towards a better understanding of those physical processes which govern not only the behaviour of simple model compounds but also that of complex materials like minerals. Concomitant with this change in direction has come an increasing awareness of the need to use the typical working tools of other disciplines.

One of the major developments in Earth Sciences in general, and mineralogy in particular, has been the growth of our understanding of the microscopic behaviour of the complex materials that make up the Earth. This has been made possible by advances in our ability to probe minerals at the atomic level, over a large range of pressure and temperature conditions. New experimental techniques include the use of scanning probe microscopies to investigate mineral surfaces, as well as the use of neutron scattering, nuclear spectroscopies and synchrotron radiation to investigate the bonding and structure of minerals. In addition, there have been major developments in computational methods so that it is now possible to calculate the electronic structure of many rock forming materials. The aim of this volume is to give a coherent survey of the latest developments in experimental and theoretical approaches to the study of microscopic propertie~ and processes in minerals. Chapters in the book cover a number of key themes in the mineral sciences such as the behaviour of minerals at extremes of pressure and temperature, ordering in complex silicates, mechanisms of water incorporation in mantle phases, the importance of reactions occurring at the mineral surface, and the ability of computational methods to provide useful, qualitative information on the bulk and surface properties of minerals. The background to several experimental techniques is covered in some detail with examples of relevance to the issues cited above.

Volume 17 of Reviews in Mineralogy is based on a short course, entitled "Thermodynamic Modeling of Geological Materials: Minerals, Fluids amd Melts," October 22-25, 1987, at the Wickenburg Inn near Phoenix, Arizona. Contents: Thermodynamic Analysis of Phase Equilibria in Simple Mineral Systems Models of Crystalline solutions Thermodynamics of Multicomponent Systems Containing Several Solid Solutions Thermodynamic Model for Aqueous Solutions of Liquid-like Density Models of Mineral Solubility in Concentrated Brines with Application to Field Observations Calculation of the Thermodynamic Properties of Aqueous Species and the Solubilities of Minerals in Supercritical Electrolyte Solutions Igneous Fluids Ore Fluids: Magmatic to Supergene Thermodynamic Models of Molecular Fluids at the Elevated Pressures and Temperatures of Crustal Metamorphism Mineral Solubilities and Speciation in Supercritical Metamorphic Fluids Development of Models for Multicomponent Melts: Analysis of Synthetic Systems Modeling Magmatic Systems: Thermodynamic Relations Modeling Magmatic Systems: Petrologic Applications

Volume 14 of Reviews in Mineralogy covers a short course about the relations among the microscopic structure of minerals and their macroscopic thermodynamic properties. Understanding the micro-to-macro relations provides a rigorous theoretical foundation for formulation of energy relations. With such a foundation, measured parameters can be understood, and extrapolation and prediction of thermodynamic properties beyond the range of measurement can be done with more confidence than if only empirical relations are used. The purpose of this course is to consider the microscopic factors that influence the free energy of minerals: atomic environments, bonding, and crystal structure. These factors influence the structural energy and the detailed nature of the lattice vibrations which are an important source of entropy and enthalpy at temperatures greater than 0 K. The same factors determine the relative energy of different phases, and thereby; the relative stability of different minerals. Configurational entropy terms arising from disorder also contribute to the energy and entropy. In transition metal compounds there are additional energy and entropy terms arising from the electronic configurations, leading to additional stabilizations, magnetic ordering, and, incidentally, color. Organized by Sue Kieffer and Alex Navrotsky, the course was presented by the ten authors of this book on the campus of Washington College in Chestertown, Maryland. This was the second of MSA's short courses to be given in conjunction with meetings of the American Geophysical Union.

30% discount for members of The Mineralogical Society of Britain and Ireland This volume addresses the fundamental factors that underlie our understanding of mineral behaviour and crystal chemistry - a timely topic given current advances in research into the complex behaviour of solids and supercomputing.

Today large numbers of geoscientists apply thermodynamic theory to solu tions of a variety of problems in earth and planetary sciences. For most problems in chemistry, the application of thermodynamics is direct and rewarding. Geoscientists, however, deal with complex inorganic and organic substances. The complexities in the nature of mineralogical substances arise due to their involved crystal structure and multicomponental character. As a result, thermochemical solutions of many geological-planetological problems should be attempted only with a clear understanding of the crystal-chemical and thermochemical character of each mineral. The subject of physical geochemistry deals with the elucidation and application of physico-chemical principles to geosciences. Thermodynamics of mineral phases and crystalline solutions form an integral part of it. Developments in mineralogic thermody namics in recent years have been very encouraging, but do not easily reach many geoscientists interested mainly in applications. This series is to provide geoscientists and planetary scientists with current information on the develop ments in thermodynamics of mineral systems, and also provide the active researcher in this rapidly developing field with a forum through which he can popularize the important conclusions of his work. In the first several volumes, we plan to publish original contributions (with an abundant supply of back ground material for the uninitiated reader) and thoughtful reviews from a number of researchers on mineralogic thermodynamics, on the application of thermochemistry to planetary phase equilibria (including meteorites), and on kinetics of geochemical reactions.