ALBERT

Description / Table of Contents: PREFACE 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-mâché (bassanite). For centuries, Al-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. We thank the authors for their comprehensive and timely efforts, and for their cooperation with our various requests regarding consistency of format and nomenclature. Special thanks are due to the numerous scientists who provided peer reviews, which substantially improved the content of the chapters. This volume would not have been possible without the usual magic touch and extreme patience of Paul H. Ribbe, Series Editor for Reviews in Mineralogy and Geochemistry. Finally, we thank our families for their support and understanding during the past several months.

Description / Table of Contents: This volume presents an extended review of the topics conveyed in a short course on Geothermal Fluid Thermodynamics held prior to the 23rd Annual V.M. Goldschmidt Conference in Florence, Italy (August 24–25, 2013). Geothermal fluids in the broadest sense span large variations in composition and cover wide ranges of temperature and pressure. Their composition may also be dynamic and change in space and time on both short and long time scales. In addition, physiochemical properties of fluids such as density, viscosity, compressibility and heat capacity determine the transfer of heat and mass by geothermal systems, whereas, in turn, the physical properties of the fluids are affected by their chemical properties. Quantitative models of the transient spatial and temporal evolution of geochemical fluid processes are, therefore, very demanding with respect to the accuracy and broad range of applicability of thermodynamic databases and thermodynamic models (or equations of state) that describe the various datasets as a function of temperature, pressure, and composition. The application of thermodynamic calculations is, therefore, a central part of geochemical studies of very diverse processes ranging from the aqueous geochemistry of near surface geothermal features including chemosynthesis and thermal biological activity, through the utilization of crustal reservoirs for CO2 sequestration and engineered geothermal systems to the formation of magmatic-hydrothermal ore deposits and, even deeper, to the de-volatilization of subducted oceanic crust and the transfer of subduction fluids and trace elements into the mantle wedge. Application of thermodynamics to understand geothermal fluid chemistry and transport requires essentially three parts: first, equations of state to describe the physiochemical system; second, a geochemical model involving minerals and fluid species; and, third, values for various thermodynamic parameters from which the thermodynamic and chemical model can be derived. The two biggest current hurdles for comprehensive geochemical modeling of geothermal systems are …

Description / Table of Contents: This volume was produced in response to the need for a comprehensive introduction to the continually evolving state of the art of synchrotron radiation applications in low-temperature geochemistry and environmental science. It owes much to the hard work and imagination of the devoted cadre of sleep-deprived individuals who blazed a trail that many others are beginning to follow. Synchrotron radiation methods have opened new scientific vistas in the earth and environmental sciences, and progress in this direction will undoubtedly continue. The organization of this volume is as follows. Chapter 1 (Brown and Sturchio) gives a fairly comprehensive overview of synchrotron radiation applications in low temperature geochemistry and environmental science. The presentation is organized by synchrotron methods and scientific issues. It also has an extensive reference list that should prove valuable as a starting point for further research. Chapter 2 (Sham and Rivers) describes the ways that synchrotron radiation is generated, including a history of synchrotrons and a discussion of aspects of synchrotron radiation that are important to the experimentalist. The remaining chapters of the volume are organized into two groups. Chapters 3 through 6 describe specific synchrotron methods that are most useful for single-crystal surface and mineral-fluid interface studies. Chapters 7 through 9 describe methods that can be used more generally for investigating complex polyphase fine-grained or amorphous materials, including soils, rocks, and organic matter. Chapter 3 (Fenter) presents the elementary theory of synchrotron X-ray reflectivity along with examples of recent applications, with emphasis on in situ studies of mineral-fluid interfaces. Chapter 4 (Bedzyk and Cheng) summarizes the theory of X-ray standing waves (XSW), the various methods for using XSW in surface and interfaces studies, and gives a brief review of recent applications in geochemistry and mineralogy. Chapter 5 (Waychunas) covers the theory and applications of grazing-incidence X-ray absorption and emission spectroscopy, with recent examples of studies at mineral surfaces. Chapter 6 (Hirschmugl) describes the theory and applications of synchrotron infrared microspectroscopy. Chapter 7 (Manceau, Marcus, and Tamura) gives background and examples of the combined application of synchrotron X-ray microfluorescence, microdiffraction, and microabsorption spectroscopy in characterizing the distribution and speciation of metals in soils and sediments. Chapter 8 (Sutton, Newville, Rivers, Lanzirotti, Eng, and Bertsch) demonstrates a wide variety of applications of synchrotron X-ray microspectroscopy and microtomography in characterizing earth and environmental materials and processes. Finally, Chapter 9 (Myneni) presents a review of the principles and applications of soft X-ray microspectroscopic studies of natural organic materials. All of these chapters review the state of the art of synchrotron radiation applications in low temperature geochemistry and environmental science, and offer speculations on future developments. The reader of this volume will acquire an appreciation of the theory and applications of synchrotron radiation in low temperature geochemistry and environmental science, as well as the significant advances that have been made in this area in the past two decades (especially since the advent of the third-generation synchrotron sources). We hope that this volume will inspire new users to "see the light" and pursue their research using the potent tool of synchrotron radiation.

Description / Table of Contents: Several years ago, John Rakovan and John Hughes (colleagues at Miami of Ohio), and later Matt Kohn (at South Carolina), separately proposed short courses on phosphate minerals to the Council of the Mineralogical Society of America (MSA). Council suggested that they join forces. Thus this volume, Phosphates: Geochemical, Geobiological, and Materials Importance, was organized. It was prepared in advance of a short course of the same title, sponsored by MSA and presented at Golden, Colorado, October 25-27. We are pleased to present this volume entitled Phosphates: Geochemical, Geobiological and Materials Importance. Phosphate minerals are an integral component of geological and biological systems. They are found in virtually all rocks, are the major structural component of vertebrates, and when dissolved are critical for biological activity. This volume represents the work of many authors whose research illustrates how the unique chemical and physical behavior of phosphate minerals permits a wide range of applications that encompasses phosphate mineralogy, petrology, biomineralization, geochronology, and materials science. While diverse, these fields are all linked structurally, crystal-chemically and geochemically. As geoscientists turn their attention to the intersection of the biological, geological, and material science realms, there is no group of compounds more germane than the phosphates. The chapters of this book are grouped into five topics: Mineralogy and Crystal Chemistry, Petrology, Biomineralization, Geochronology, and Materials Applications. In the first section, three chapters are devoted to mineralogical aspects of apatite, a phase with both inorganic and organic origins, the most abundant phosphate mineral on earth, and the main mineral phase in the human body. Monazite and xenotime are highlighted in a fourth chapter, which includes their potential use as solid-state radioactive waste repositories. The Mineralogy and Crystal Chemistry section concludes with a detailed examination of the crystal chemistry of 244 other naturally-occurring phosphate phases and a listing of an additional 126 minerals. In the Petrology section, three chapters detail the igneous, metamorphic, and sedimentary aspects of phosphate minerals. A fourth chapter provides a close look at analyzing phosphates for major, minor, and trace elements using the electron microprobe. A final chapter treats the global geochemical cycling of phosphate, a topic of intense, current geochemical interest. The Biomineralization section begins with a summary of the current state of research on bone, dentin and enamel phosphates, a topic that crosses disciplines that include mineralogical, medical, and dental research. The following two chapters treat the stable isotope and trace element compositions of modern and fossil biogenic phosphates, with applications to paleontology, paleoclimatology, and paleoecology. The Geochronology section focuses principally on apatite and monazite for U-ThPb, (U- Th)/He, and fission-track age determinations; it covers both classical geochronologic techniques as well as recent developments. The final section-Materials Applications-highlights how phosphate phases play key roles in fields such as optics, luminescence, medical engineering and prosthetics, and engineering of radionuclide repositories. These chapters provide a glimpse of the use of natural phases in engineering and biomedical applications and illustrate fruitful areas of future research in geochemical, geobiological and materials science. We hope all chapters in this volume encourage researchers to expand their work on all aspects of natural and synthetic phosphate compounds.

Description / Table of Contents: In the two decades since J. Alexander Speer's Zircon chapter in Orthosilicates (Reviews in Mineralogy, Vol. 5), much has been learned about the internal textures, trace-element and isotope geochemistry (both radiogenic and stable) and chemical and mechanical stability of zircon. The application of this knowledge and the use of zircon in geologic studies have become widespread. Today, the study of zircon exists as the pseudo-discipline of "zirconology" that involves materials scientists and geoscientists from across a range of sub-disciplines including stable and radiogenic isotopes, sedimentology, petrology, trace elements and experimental mineralogy. Zirconology has become an important field of research, so much so that coverage of the mineral zircon in a review volume that included zircon as one of many accessory minerals would not meet the needs or interests of the zirconology community in terms of depth or breadth of coverage. The sixteen chapters in this volume cover the most important aspects of zircon-related research over the past twenty-years and highlight possible future research avenues. Finch and Hanchar (Chapter 1) review the structure of zircon and other mineral (and synthetic) phases with the zircon structure. In most rock types where zircon occurs it is a significant host of the rare-earth elements, Th and U. The abundances of these elements and the form of chondrite-normalized rare-earth element patterns may provide significant information on the processes that generate igneous and metamorphic rocks. The minor and trace element compositions of igneous, metamorphic and hydrothermal zircons are reviewed by Hoskin and Schaltegger in Chapter 2. The investigation of melt inclusions in zircon is an exciting line of new research. Trapped melt inclusions can provide direct information of the trace element and isotopic composition of the melt from which the crystal formed as a function of time throughout the growth of the crystal. Thomas et a!. (Chapter 3) review the study of melt inclusions in zircon. Hanchar and Watson (Chapter 4) review experimental and natural studies of zircon saturation and the use of zircon saturation thermometry for natural rocks. Cation diffusion and oxygen diffusion in zircon is discussed by Cherniak and Watson (Chapter 5). Diffusion studies are essential for providing constraints on the quality of trace element and isotope data and for providing estimates of temperature exposure in geological environments. Zircon remains the most widely utilized accessory mineral for U- Th-Pb isotope geochronology. Significant instrumental and analytical developments over the past thirty years mean that zircon has an essential role in early Achaean studies, magma genesis, and astrobiology. Four chapters are devoted to different aspects of zircon geochronology. The first of these four, Chapter 6 by Davis et a!., reviews the historical development of zircon geochronology from the mid-1950s to the present; the following three chapters focus on particular techniques for zircon geochronology, namely ID-TIMS (Parrish and Noble, Chapter 7), SIMS (Ireland and Williams, Chapter 8) and ICP-MS (Kosier and Sylvester, Chapter 9). The application of zircon chronology in constraining sediment provenance.and the calibration ofthe geologic time-scale are reviewed by Fedo et al. (Chapter 10) and Bowring and Schmitz (Chapter 11), respectively. Other isotopic systematics are reviewed for zircon by Kinny and Maas (Chapter 12), who discuss the application of Nd-Sm and Lu-Hf isotopes in zircon to petrogenetic studies, and by Valley (Chapter 13), who discusses the importance of oxygen isotopic studies in traditional and emerging fields of geologic study. As a host of U and Th, zircon is subject to radiation damage. Radiation damage is likely responsible for isotopic disturbance and promotes mechanical instability. There is increasing interest in both the effect of radiation damage on the zircon crystal structure and mechanisms of damage and recrystallization, as well as the structure of the damaged phase. These studies contribute to an overall understanding of how zircon may behave as a waste-form for safe disposal of radioactive waste and are discussed by Ewing et a!. (Chapter 14). The spectroscopy of zircon, both crystalline and metamict is reviewed by Nadsala et a!. (Chapter 15). The final chapter, by Corfu et al. (Chapter 16), is an atlas of internal textures of zircon. The imaging of internal textures in zircon is essential for directing the acquisition of geochemical data and to the integrity of conclusions reached once data has been collected and interpreted. This chapter, for the first time, brings into one place textural images that represent common and not so common textures reported in the literature, along with brief interpretations of their significance. There is presently no comparable atlas. It is intended that this chapter will become a reference point for future workers to compare and contrast their own images against. The chapters in this volume of Reviews in Mineralogy and Geochemistry were prepared for presentation at a Short Course, sponsored by the Mineralogical Society of America (MSA) in Freiburg, Germany, April 3-4, 2003. This preceded a joint meeting of the European Union of Geology, the American Geophysical Union and the European Geophysical Society held in Nice, France, April 6-11, 2003.

Description / Table of Contents: This volume was prepared for Short Course on Stable Isotope Geochemistry presented November 2-4, 2001 in conjunction with the annual meetings of the Geological Society of America in Boston, Massachusetts. This volume follows the 1986 Reviews in Mineralogy (Vol. 16) in approach but reflects significant changes in the field of Stable Isotope Geochemistry. In terms of new technology, new sub-disciplines, and numbers of researchers, the field has changed more in the past decade than in any other since that of its birth. Unlike the 1986 volume, which was restricted to high temperature fields, this book covers a wider range of disciplines. However, it would not be possible to fit a comprehensive review into a single volume. Our goal is to provide state-ofthe-art reviews in chosen subjects that have emerged or advanced greatly since 1986. v The field of Stable Isotope Geochemistry was born of a good idea and nurtured by technology. In 1947, Harold Urey published his calculated values of reduced partition function for oxygen isotopes and his idea (a good one!) that the fractionation of oxygen isotopes between calcite and water might provide a means to estimate the temperatures of geologic events. Building on wartime advances in electronics, Alfred Nier then designed and built the dual-inlet, gassource mass-spectrometer capable of making measurements of sufficient precision and accuracy. This basic instrument and the associated extraction techniques, mostly from the 1950s, are still in use in many labs today. These techniques have become "conventional" in the sense of traditional, and they provide the benchmark against which the accuracy of other techniques is compared. The 1986 volume was based almost exclusively on natural data obtained solely from conventional techniques. Since then, revolutionary changes in sample size, accuracy, and cost have resulted from advances in continuous flow massspectrometry, laser heating, ion microprobes, and computer automation. The impact of new technology has differed by discipline. Some areas have benefited from vastly enlarged data sets, while others have capitalized on in situ analysis and/or micro- to nanogram size samples, and others have developed because formerly intractable samples can now be analyzed. Just as Stable Isotope Geochemistry is being reborn by new good ideas, it is still being nurtured by new technology. The organization of the chapters in this book follows the didactic approach of the 2001 short course in Boston. The first three chapters present the principles and data base for equilibrium isotope fractionation and for kinetic processes of exchange. Both inorganic and biological aspects are considered. The next chapter reviews isotope compositions throughout the solar system including massindependent fractionations that are increasingly being recognized on Earth. The fifth chapter covers the primitive compositions of the mantle and subtle variations found in basalts. This is followed by three chapters on metamorphism, isotope thermometry, fluid flow, and hydrothermal alteration. The next chapter considers water cycling in the atmosphere and the ice record. And finally, there are four chapters on the carbon cycle, the sulfur cycle, organic isotope geochemistry and extinctions in the geochemical record.

Description / Table of Contents: PREFACE Phase transformations occur in most types of materials, including ceramics, metals, polymers, diverse organic and inorganic compounds, minerals, and even crystalline viruses. They have been studied in almost all branches of science, but particularly in physics, chemistry, engineering, materials science and earth sciences. In some cases the objective has been to produce materials in which phase transformations are suppressed, to preserve the structural integrity of some engineering product, for example, while in other cases the objective is to maximise the effects of a transformation, so as to enhance properties such as superconductivity, for example. A long tradition of studying transformation processes in minerals has evolved from the need to understand the physical and thermodynamic properties of minerals in the bulk earth and in the natural environment at its surface. The processes of interest have included magnetism, ferroelasticity, ferroelectricity, atomic ordering, radiation damage, polymorphism, amorphisation and many others—in fact there are very few minerals which show no influence of transformation processes in the critical range of pressures and temperatures relevant to the earth. As in all other areas of science, an intense effort has been made to turn qualitative under-standing into quantitative description and prediction via the simultaneous development of theory, experiments and simulations. In the last few years rather fast progress has been made in this context, largely through an inter-disciplinary effort, and it seemed to us to be timely to produce a review volume for the benefit of the wider scientific community which summarises the current state of the art. The selection of transformation processes covered here is by no means comprehensive, but represents a coherent view of some of the most important processes which occur specifically in minerals. A number of the contributors have been involved in a European Union funded research network with the same theme, under the Training and Mobility of Researchers programme, which has stimulated much of the most recent progress in some of the areas covered. This support is gratefully acknowledged.

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: Die polarisationsmikroskopische Untersuchung von Materialien (Minerale, Gesteine, Erze, Werkstoffe, Syntheseprodukte) im Durchlicht und Auflicht ist eine der klassischen und bis heute unverzichtbaren mineralogischen Untersuchungsmethoden. Sie ermöglicht es, die festen Substanzen (kristallin, amorph) zerstörungsfrei und mit relativ hoher Ortsauflösung in ihrem Aggregatverband meist sicher zu identifizieren, ihre Zusammensetzungen abzu-schätzenund darüber hinaus aus den Gefügemerkmalen des Materials (Struktur, Textur, Phasenbestand, Phasenbeziehungen, Reaktionstexturen etc.) wichtige Hinweise auf dessen Bildungsgeschichte abzuleiten. Polarisationsmikroskopie ist dadurch den integrierenden Analyseverfahren an Probenpulvern zur Bestimmung des Phasenbestandes (RDA) und der chemischen Zusammensetzung (RFA, AAS) deutlich überlegen. Polarisationsmikroskopie gelangt jedoch an die Grenzen, wenn z.B. die chemische Zusammensetzung komplexer Mischphasen genau bestimmt werden muss oder die Feinkörnigkeit des Materials eine Bestimmung der einzelnen Phasen nicht mehr zulässt. Eine moderne materialwissen-schaftlicheUntersuchung wird daher stets entsprechend der jeweiligen Problemstellung und Materialbeschaffenheit die polarisationsmikroskopische Bearbeitung mit zerstörungsfreier, hoch ortsauflösender Analytik (EMS, REM-EDX, TEM) verbinden. Die polarisationsmikroskopischen Bestimmungsmethoden der durchsichtigen amorphen und kristallinen Phasen (Gläser, Minerale, synthetische Substanzen) und die hierfür notwendigen kristalloptischen Zusammenhänge sind in zahlreichen deutsch-und englischsprachigen Lehrbüchern ausführlich behandelt (siehe Literaturauswahl). Die folgende Einführung in die Mineralbestimmung im Dünnschliff kann daher auf eine breite Darstellung des Stoffes verzichten. Für die praktische Arbeit am Polarisationsmikroskop genügt es, die erforder-lichenSachverhalte in einer prägnanten und auch dem mineralogisch wenig vorgebildeten Mikroskopierenden verständlichen Anleitung zusammenzufassen. Kristalloptische und kristallographische Grundlagen werden nur soweit behandelt, als sie für das Verständnis der beobachteten optischen Phänomene und morphologischen Merkmale notwendig erscheinen. Die polarisationsmikroskopische Bestimmung der Minerale erfolgt anhand ihrer optischen und morphologischen Kennzeichen. Umfangreiche Tabellenwerke stellen die hierfür benötigte Datenbasis für eine außerordentliche Vielzahl von natürlichen Mineralen und synthetischen Phasen bereit (siehe Literaturauswahl). Grundlage dieses Leitfadens bildet das in langjähriger Mikroskopiepraxis bewährte, seit einigen Jahren jedoch vergriffene Clausthaler Heft 14 „Methoden der Dünnschliffmikro-skopie“von G. Müller & M. Raith. Wir haben den Text weitgehend übernommen, das Bildmaterial jedoch graphisch modern überarbeitet, mit weiteren Abbildungen ergänzt sowie die vielfältigen Phänomene mit zahlreichen Mikrofotos veranschaulicht. Wir hoffen, dass dieser Leitfaden dem Studierenden das notwendige Rüstzeug für einen erfolgreichen Einstieg in die Polarisationsmikroskopie bereitstellt. Anregungen und Hinweise zur Darstellung sind jederzeit willkommen!

Description / Table of Contents: Exactly 100 years before the publication of this volume, the first paper which calculated the half-life for the newly discovered radioactive substance U-X (now called 234Th), was published. Now, in this volume, the editors Bernard Bourdon, Gideon Henderson, Craig Lundstrom and Simon Turner have integrated a group of contributors who update our knowledge of U-series geochemistry, offer an opportunity for non-specialists to understand its basic principles, and give us a view of the future of this active field of research. In this volume, for the first time, all the methods for determining the uranium and thorium decay chain nuclides in Earth materials are discussed. It was prepared in advance of a two-day short course (April 3-4, 2003) on U-series geochemistry, jointly sponsored by GS and MSA and presented in Paris, France prior to the joint EGS/AGU/EUG meeting in Nice. The discovery of the 238U decay chain, of course, started with the seminal work of Marie Curie in identifying and separating 226Ra. Through the work of the Curies and others, all the members of the 238U decay chain were identified. An important milestone for geochronometrists was the discovery of 230Th (called Ionium) by Bertram Boltwood, the Yale scientist who also made the first age determinations on minerals using the U-Pb dating method (Boltwood in 1906 established the antiquity of rocks and even identified a mineral from Sri Lanka-then Ceylon as having an age of 2.1 billion years!) The application of the 238U decay chain to the dating of deep sea sediments was by Piggott and Urry in 1942 using the "Ionium" method of dating. Actually they measured 222Ra (itself through 222Rn) assuming secular equilibrium had been established between 230Th and 226Ra. Although 230Th was measured in deep sea sediments by Picciotto and Gilvain in 1954 using photographic emulsions, it was not until alpha spectrometry was developed in the late 1950's that 20Th was routinely measured in marine deposits. Alpha spectrometry and gamma spectrometry became the work horses for the study of the uranium and thorium decay chains in a variety of Earth materials. These ranged from 222Rn and its daughters in the atmosphere, to the uranium decay chain nuclides in the oceanic water column, and volcanic rocks and many other systems in which either chronometry or element partitioning, were explored. Much of what we learned about the 238U, 235U and 232Th decay chain nuclides as chronometers and process indicators we owe to these seminal studies based on the measurement of radioactivity. The discovery that mass spectrometry would soon usurp many of the tasks performed by radioactive counting was in itself serendipitous. It came about because a fundamental issue in cosmochemistry was at stake. Although variation in 235U/238U had been reported for meteorites the results were easily discredited as due to analytical difficulties. One set of results, however, was published by a credible laboratory long involved in quality measurements of high mass isotopes such as the lead isotopes. The purported discovery of 235U/238U variations in meteorites, if true, would have consequences in defining the early history of the formation of the elements and the development of inhomogeneity of uranium isotopes in the accumulation of the protoplanetary materials of the Solar System. Clearly the result was too important to escape the scrutiny of falsification implicit in the way we do science. The Lunatic Asylum at Caltech under the leadership of Jerry Wasserburg took on that task. Jerry Wasserburg and Jim Chen clearly established the constancy and Earth-likeness of 235U/238U in the samplable universe. In the hands of another member of the Lunatic Asylum, Larry Edwards, the methodology was transformed into a tool for the study of the 238U decay chain in marine systems. Thus the mass spectrometric techniques developed provided an approach to measuring the U and Th isotopes in geological materials as well as cosmic materials with the same refinement and accommodation for small sample size. Soon after this discovery the harnessing of the technique to the measurement of all the U isotopes and all the Th isotopes with great precision immediately opened up the entire field of uranium and thorium decay chain studies. This area of study was formerly the poaching ground for radioactive measurements alone but now became part of the wonderful world of mass spectrometric measurements. (The same transformation took place for radiocarbon from the various radioactive counting schemes to accelerator mass spectrometry.) No Earth material was protected from this assault. The refinement of dating corals, analyzing volcanic rocks for partitioning and chronometer studies and extensions far and wide into ground waters and ocean bottom dwelling organisms has been the consequence of this innovation. Although Ra isotopes, 210Pb and 210Po remain an active pursuit of those doing radioactive measurements, many of these nuclides have also become subject to the mass spectrometric approach. In this volume, for the first time, all the methods for determining the uranium and thorium decay chain nuclides in Earth materials are discussed. The range of problems solvable with this approach is remarkable-a fitting, tribute to the Curies and the early workers who discovered them for us to use.