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RIMG v.61, Sulfide Mineralogy and Geochemistry


Sulfide Mineralogy and Geochemistry
Reviews in Mineralogy & Geochemistry Volume 61
David J. Vaughan, editor

Much has been written about sulfide minerals since the publication of Volume 1 of the Reviews in Mineralogy (and Geochemistry) series. As one of the authors of that volume, I look back and realize that although we told what we knew about sulfides at the time, there was a lot we didn't know and it is exciting that a lot more has been discovered in the following 20+ years. Since then, the techniques and theories have advanced remarkably, especially in the development of advanced analytical instrumentation and the use of computers for display and analysis of crystal structures, chemical bonding, ab initio calculations, control of apparatus, construction of maps and diagrams, and storage and manipulation of data. I am very much impressed by David Vaughan's influence on sulfide mineralogy and geochemistry, and congratulate him for producing so much useful information over the years and also for his efforts in organizing and editing this Volume. In Chapter 1, David reviews the reasons for producing a volume focused on sulfides, the relevant literature, and its scope and content. Although the emphasis is on sulfides, selenides and tellurides are mentioned in a few of the chapters, and there is also some discussion of the roles of arsenic, antimony, and sulfates.

Chapter 2, Crystal Structures of Sulfides and other Chalcogenides, by Emil Makovicky contains a remarkable review of sulfide structures, with many illustrations of crystal structures and related information. In reading this chapter, I thought to myself how nice it would be to have an index to locate sections on specific minerals of interest -- this is a comment I have also seen in other book reviews. However, I then realized that this is not so important today if text is available in electronic form. I downloaded several chapters in pdf format via GeoScienceWorld, a service that is available through our Library at the University of Arizona. Then, using Adobe Reader 7, I was able to search with ease for any mineral name or other topic of interest. The answers appear in the context in which they were written, so this is really better than looking up words and relevant pages in a printed index. Chapter 3 is on Electrical and Magnetic Structures of Sulfides by Carolyn Pearce, Richard Patrick, and David Vaughan. Virtually all industrial applications related to sulfides depend on their electrical and/or magnetic structures. This includes not only uses of sulfides in electronics and as nanoparticles, but also in exploration for ore deposits and extraction of sulfides from bulk material. Chapter 4 is Spectroscopic Studies of Sulfides by Paul Wincott and David Vaughan. This chapter reviews a range of spectroscopies useful for investigations of sulfides, including infrared to ultraviolet, x-ray emission and absorption, Mössbauer, nuclear magnetic resonance, and a number of other techniques. Mössbauer studies at high pressure have been especially important for understanding phase changes in iron sulfides. Chapter 5 is Chemical Bonding in Sulfide Minerals by David Vaughan and Kevin Rosso. Chemical bonding is sulfides is much more complex than in oxides and it has taken a long time for useful bonding theory to be incorporated into sulfide studies. However, the authors demonstrate that substantial progress is being made in both qualitative and quantitative calculations to interpret and predict sulfide crystal structures.

Chapter 6, Thermochemistry of Sulfide Mineral Solutions by Richard Sack and Denton Ebel, begins with a discussion of phase relations and solid-solution thermochemistry, and continues with examples of equilibria and non-equilibria of a range of sulfide systems. It also covers experimental methods in sulfide research. This chapter is followed by a complementary discussion in Chapter 7, Phase Equilibria at High Temperatures, by Michael Fleet. This chapter covers primarily systems containing first-row transition-metal sulfides, and includes a short section on Fe-S at high pressures. Chapter 8 is Metal Sulfide Complexes and Clusters by David Rickard and George Luther, III. The emphasis here is on sulfides in aqueous systems and the role of clusters and complexes. This is, in fact, a very complex part of sulfide research because, as the authors note, it is often difficult to determine the actual molecular structure and composition of a sulfide complex in a dilute solution, so geochemists often just focus on measuring the stabilities of complexes. The chapter ends with an interesting discussion of the relationship between complexes, clusters, and solid phases. The next two chapters are both by Kevin Rosso and David Vaughan with Chapter 9 describing Sulfide Mineral Surfaces and Chapter 10 the Reactivity of Sulfide Mineral Surfaces. Surface studies have benefited enormously in the past 20 years or so by the development of a variety of techniques for characterizing surface structures and their reactivity with their environment. Among the techniques mentioned are EXAFS, XANES, the scanning tunneling microscope (STM) and atomic force microscope (AFM). Surface studies involve identifying the crystallographic orientation of the fractured or cleaved surface, the presence of vacancies, and the atoms or ions exposed at the surface. Chapter 10 discusses surface reactions with gaseous species such as O2, H2O, H2S, and CH3OH, catalysis, and metal ion uptake at sulfide surfaces. Computational analysis requiring supercomputers is also a developing field. Chapter 11, Sulfide Mineral Precipitation from Hydrothermal Fluids by Mark Reed and James Palandri, explores how sulfides dissolve or precipitate in fluids with varying temperature, pH, and chemical composition.

Chapter 12 is Sulfur Isotope Geochemistry of Sulfide Minerals by Robert Seal, II. Seal provides basic understanding of stable isotope geochemistry, analytical methods, and factors controlling sulfur isotope fractionations. Seal then provides a number of examples showing how knowledge of sulfur isotope variations aid in the understanding of systems containing sulfide minerals, such as meteorites, marine sediments, igneous rocks, ore deposits, and seafloor hydrothermal systems. Chapter 13 is Sulfides in Biosystems by Mihály Pósfai and Rafal Dunin-Borkowski. Two concepts described here are very interesting, biologically controlled mineralization (BCM) and biologically induced mineralization (BIM). The authors relate that while only a few examples of BCM are known, iron sulfides form in vast quantities by BIM and affect the global cycling of iron, sulfur, oxygen, and carbon. Of particular interest are magnetotactic bacteria that contain intracellular magnetic iron oxide or sulfide minerals. Some magnetotactic bacteria contain pyrite, mackinawite, or greigite. This area of research is very promising and many scientists believe that sulfides may play a significant role in the origin of life

In conclusion, I recommend this Volume very highly as an authoritative presentation of current knowledge and understanding of sulfide minerals' chemistry, physical properties, and geological importance. Although there was no Short Course associated with production of the Volume, I think it has great potential for being the foundation of one or more international research symposia on the role of sulfides in the geosciences and related areas of science and technology.

Charles T. Prewitt
Department of Geosciences
University of Arizona
Tucson, AZ 85747, USA