ALBERT

Description / Table of Contents: The Mineralogical Society of America sponsored a short course for which this was the text at Stanford University December 9 and 10, 1995, preceding the Fall Meeting of the American Geophysical Union and MSA in San Fransisco, with about 100 professionals and graduate students in attendance. A silicate melt phase is the essential component of nearly all igneous processes, with dramatic consequences for the properties of the Earth's interior. Throughout Earth history and continuing to the present day, silicate melts have acted as transport agents in the chemical and physical differentiation of the Earth into core, mantle and crust. The occurrence of such magmatic processes leads to the definition of our planet as "active," and the resulting volcanism has a profound impact on the Earth's atmosphere, hydrosphere and biosphere. Although near-surface melts are observed directly during volcanic eruptions, the properties of magmas deep within the Earth must be characterized and constrained by laboratory experiments. Many of these experiments are designed to aid in developing an atomic level understanding of the structure and dynamics of silicate melts under the P- T conditions of the Earth's crust and mantle, which will make extrapolation from the laboratory results to the behavior of natural magmas as reliable as possible. Silicate melts are also the archetypal glass-forming materials. Because of the ready availability of raw materials, and the ease with which molten silicates can be vitrified, commercial "glass" has necessarily implied a silicate composition, over most of the history of glass technology. The properties of the melt, or "slag" in metallurgical extractions, determine the nature of the glass formed, and the needs of the glass industry have provided much of the impetus for understanding the structure-property relations of molten silicates as well as for the glasses themselves. It is now recognized that any liquid might become glassy, if cooled rapidly enough, and understanding the thermodynamic and kinetic aspects of the glass transition, or passage between the liquid and glassy states of matter, has become a subject of intense interest in fundamental physics and chemistry. Glasses have also been studied in many geochemical investigations, often as substitutes for the high temperature melts, with the results being extrapolated to the liquid state. In many cases, in situ techniques for direct investigation of these refractory systems have only recently become available. Much valuable information concerning the melt structure has been gleaned from such studies. Nevertheless, there are fundamental differences between the liquid and glassy states. In liquids, the structure becomes progressively more disordered with increasing temperature, which usually gives rise to major changes in all thermodynamic properties and processes. These changes must, in general, be investigated directly by in situ studies at high temperature. Studies of glass only represent a starting point, which reflect a frozen image of the melt "structure" at the glass transition temperature. This is generally hundreds of degrees below the near-liquidus temperatures of greatest interest to petrologists. Since the early 1980s, a much deeper understanding of the structure, dynamics, and properties of molten silicates has been developed within the geochemical community, applying techniques and concepts developed within glass science, extractive metallurgy and liquid state physics. Some of these developments have far-reaching implications for igneous petrology. The purpose of this Short Course and volume is to introduce the basic concepts of melt physics and relaxation theory as applied to silicate melts, then to describe the current state of experimental and computer simulation techniques for exploring the detailed atomic structure and dynamic processes which occur at high temperature, and finally to consider the relationships between melt structure, thermodynamic properties and rheology within these liquids. These fundamental relations serve to bridge the extrapolation from often highly simplified melt compositions studied in the laboratory to the multicomponent systems found in nature. This volume focuses on the properties of simple model silicate systems, which are usually volatile-free. The behavior of natural magmas has been summarized in a previous Short Course volume (Nicholls and Russell, editors, 1990: Reviews in Mineralogy, Vol. 24), and the effect of volatiles on magmatic properties in yet another (Carroll and Holloway, editors, 1994: Vol. 30). In the chapters by Moynihan, by Webb and Dingwell, and by Richet and Bottinga, the concepts of relaxation and the glass transition are introduced, along with techniques for studying the rheology of silicate liquids, and theories for understanding the transport and relaxation behavior in terms of the structure and thermodynamic properties of the liquid. The chapter by Dingwell presents applications of relaxation-based studies of melts in the characterization of their properties. Chapters by Stebbins, by Brown, Farges and Calas, and by McMillan and Wolf present the principal techniques for studying the melt structure and atomic scale dynamics by a variety of spectroscopic and diffraction methods. Wolf and McMillan summarize our current understanding of the effects of pressure on silicate glass and melt structure. Chapters by Navrotsky and by Hess consider the thermodynamic properties and mixing relations in simple and multicomponent aluminosilicate melts, both from a fundamental structural point of view and empirical chemical models which can be conveniently extrapolated to natural systems. The chapter by Chakraborty describes the diffusivity of chemical species in silicate melts and glasses, and the chapter by Poole, McMillan and Wolf discusses the application of computer simulation methods to understanding the structure and dynamics of molten silicates. The emphasis in this volume is on reviewing the current state of knowledge of the structure, dynamics and physical properties of silicate melts, along with present capabilities for studying the molten state under conditions relevant to melting within the Earth, with the intention that these techniques and results can then be applied to understanding and modeling both the nature of silicate melts and the role of silicate melts in nature.

Description / Table of Contents: The review chapters in this volume were the basis for a short course on sulfate minerals sponsored by the Mineralogical Society of America (MSA) November 11-12, 2000 in Tahoe City, California, prior to the Annual Meeting of MSA, the Geological Society of America, and other associated societies in nearby Reno, Nevada. The conveners of the course (and editors of this volume of Reviews in Mineralogy and Geochemistry), Alpers, John Jambor, and Kirk Nordstrom, also organized related topical sessions at the GSA meeting on sulfate minerals in both hydrothermal and low-temperature environments. Sulfate is an abundant and ubiquitous component of Earth's lithosphere and hydrosphere. Sulfate minerals represent an important component of our mineral economy, the pollution problems in our air and water, the technology for alleviating pollution, and the natural processes that affect the land we utilize. Vast quantities of gypsum are consumed in the manufacture of wallboard, and calcium sulfates are also used in sculpture in the forms of alabaster (gypsum) and papier-mache (bassanite). For centuries, AI-sulfate minerals, or "alums," have been used in the tanning and dyeing industries, and these sulfate minerals have also been a minor source of aluminum metal. Barite is used extensively in the petroleum industry as a weighting agent during drilling, and celestine (also known as "celestite") is a primary source of strontium for the ceramics, metallurgical, glass, and television face-plate industries. Jarosite is a major waste product of the hydrometallurgical processing of zinc ores and is used in agriculture to reduce alkalinity in soils. At many mining sites, the extraction and processing of coal or metal-sulfide ores (largely for gold, silver, copper, lead, and zinc) produce waste materials that generate acid-sulfate waters rich in heavy metals, commonly leading to contamination of water and sediment. Concentrated waters associated with mine wastes may precipitate a variety of metal-sulfate minerals upon evaporation, oxidation, or neutralization. Some of these sulfate minerals are soluble and store metals and acidity only temporarily, whereas others are insoluble and improve water quality by removing metals from the water column. There is considerable scientific interest in the mineralogy and geochemistry of sulfate minerals in both high-temperature (igneous and hydrothermal) and low-temperature (weathering and evaporite) environments. The physical scale of processes affected by aqueous sulfate and associated minerals spans from submicroscopic reactions at mineral-water interfaces to global issues of oceanic cycling and mass balance, and even to extraterrestrial applications in the exploration of other planets and their satellites. In mineral exploration, minerals of the alunite-jarosite supergroup are recognized as key components of the advanced argillic (acid-sulfate) hydrothermal alteration assemblage, and supergene sulfate minerals can be useful guides to primary sulfide deposits. The role of soluble sulfate minerals formed from acid mine drainage (and its natural equivalent, acid rock drainage) in the storage and release of potentially toxic metals associated with wet-dry climatic cycles (on annual or other time scales) is increasingly appreciated in environmental studies of mineral deposits and of waste materials from mining and mineral processing. This volume compiles and synthesizes current information on sulfate minerals from a variety of perspectives, including crystallography, geochemical properties, geological environments of formation, thermodynamic stability relations, kinetics of formation and dissolution, and environmental aspects. The first two chapters cover crystallography (Chapter 1) and spectroscopy (Chapter 2). Environments with alkali and alkaline earth sulfates are described in the next three chapters, on evaporites (Chapter 3), barite-celestine deposits (Chapter 4), and the kinetics of precipitation and dissolution of gypsum, barite, and celestine (Chapter 5). Acidic environments are the theme for the next four chapters, which cover soluble metal salts from sulfide oxidation (Chapter 6), iron and aluminum hydroxysulfates (Chapter 7), jarosites in hydrometallugy (Chapter 8), and alunite-jarosite crystallography, thermodynamics, and geochronology (Chapter 9). The next two chapters discuss thermodynamic modeling of sulfate systems from the perspectives of predicting sulfate-mineral solubilities in waters covering a wide range in composition and concentration (Chapter 10) and predicting interactions between sulfate solid solutions and aqueous solutions (Chapter 11). The concluding chapter on stable-isotope systematics (Chapter 12) discusses the utility of sulfate minerals in understanding the geological and geochemical processes in both high- and low-temperature environments, and in unraveling the past evolution of natural systems through paleoclimate studies.

Description / Table of Contents: The review chapters in this volume were the basis for a short course on molecular modeling theory jointly sponsored by the Geochemical Society (GS) and the Mineralogical Society of America (MSA) May 18-20, 2001 in Roanoke, Virginia which was held prior to the 2001 Goldschmidt Conference in nearby Hot Springs, Virginia. Dr. William C. Luth has had a long and distinguished career in research, education and in the government. He was a leader in experimental petrology and in training graduate students at Stanford University. His efforts at Sandia National Laboratory and at the Department of Energy's headquarters resulted in the initiation and long-term support of many of the cutting edge research projects whose results form the foundations of these short courses. Bill's broad interest in understanding fundamental geochemical processes and their applications to national problems is a continuous thread through both his university and government career. He retired in 1996, but his efforts to foster excellent basic research, and to promote the development of advanced analytical capabilities gave a unique focus to the basic research portfolio in Geosciences at the Department of Energy. He has been, and continues to be, a friend and mentor to many of us. It is appropriate to celebrate his career in education and government service with this series of courses in cutting-edge geochemistry that have particular focus on Department of Energy-related science, at a time when he can still enjoy the recognition of his contributions. Molecular modeling methods have become important tools in many areas of geochemical and mineralogical research. Theoretical methods describing atomistic and molecular-based processes are now commonplace in the geosciences literature and have helped in the interpretation of numerous experimental, spectroscopic, and field observations. Dramatic increases in computer power-involving personal computers, workstations, and massively parallel supercomputers-have helped to increase our knowledge of the fundamental processes in geochemistry and mineralogy. All researchers can now have access to the basic computer hardware and molecular modeling codes needed to evaluate these processes. The purpose of this volume of Reviews in Mineralogy and Geochemistry is to provide the student and professional with a general introduction to molecular modeling methods and a review of various applications of the theory to problems in the geosciences. Molecular mechanics methods that are reviewed include energy minimization, lattice dynamics, Monte Carlo methods, and molecular dynamics. Important concepts of quantum mechanics and electronic structure calculations, including both molecular orbital and density functional theories, are also presented. Applications cover a broad range of mineralogy and geochemistry topics-from atmospheric reactions to fluid-rock interactions to properties of mantle and core phases. Emphasis is placed on the comparison of molecular simulations with experimental data and the synergy that can be generated by using both approaches in tandem. We hope the content of this review volume will help the interested reader to quickly develop an appreciation for the fundamental theories behind the molecular modeling tools and to become aware of the limits in applying these state-of-the-art methods to solve geosciences problems.

Description / Table of Contents: This volume represents the proceedings of a course by the same title held at Harbor House Resort and Conference Center on Nantucket Island off the coast of Massachusetts, October 22-24, 1993. Numerous minerals are known to induce pulmonary diseases. The asbestos minerals (chrysotile and asbestiform amphiboles) are by far the most infamous. However, a number of silica polymorphs, clays, and zeolites have also been studied in great detail, as have several titania polymorphs, hematite, and magnetite (which are often used as negative controls in biological experiments). In fact, the relatively recent attention received by erionite (a fibrous zeolite) has arguably made it the most notorious of the minerals studied thus far. The processes that lead to the development of disease (or pathogenesis) by minerals very likely occur at or near the mineral-fluid interface (as do many geochemical processes!). Thus the field of "mineral-induced pathogenesis" is a prime candidate for interdisciplinary research, involving mineral scientists, health scientists, petrologists, pathologists, geochemists, biochemists, and surface scientists, to name a few. The success of such an interdisciplinary approach rests on the ability of scientists in very different fields to communicate, and this is hampered by vocabulary barriers and an unfamiliarity with concepts, approaches, and problems. It can be difficult enough for a geoscientist or bioscientist to maintain fluency in the many fields tangential to his or her own field, and this problem is only exacerbated when one investigates problems that are crossdisciplinary. Nevertheless, important advances can be facilitated if these barriers are overcome. This review volume and the short course upon which it was based are intended to provide some of the necessary tools for the researcher interested in this area of interdisciplinary research. The chapters present several of the important problems, concepts, and approaches from both the geological and biological ends of the spectrum. These two extremes are partially integrated throughout the book by cross-referencing between chapters. Chapter 1 also presents a general introduction into the ways in which these two areas overlap. However, many of the areas ripe for the interdisciplinarian will become obvious after reading the various chapters. The final chapter of this book discusses some of the regulatory aspects of minerals. Ultimately, the regulatory arena is where this type of interdisciplinary approach can make an impact, and hopefully better communication between all parties will accomplish this goal. A glossary is included at the end of this book, because the complexity of scientific terms in the two fields can thwart even the most enthusiastic of individuals.