ALBERT

Description / Table of Contents: Contents:Crystal Structure - Species - Crystallisation.- Crystal Chemistry of Clay Minerals.- Energy Balances.- Isotopic Composition of Clay Minerals.- Surface Properties.- Clays in Soils and Weathered Rocks.- Clays in Sedimentary Environments.- Diagenesis and Very Low-Grade Metamorphism.- Hydrothermal Process- Thermal Metamorphism.- Clays Under Extreme Conditions

Description / Table of Contents: In Materials Science, investigations aiming to prepare new types of molecular sieves (porous materials) have opened a productive field of research inspired by the crystal structures of minerals. These new molecular sieves are distinct from zeolites in that they have different kinds of polyhedra that build up their structures. Of particular interest are the new molecular sieves characterized by a mixed "octahedral"-tetrahedral framework (heteropolyhedral frameworks), instead of a purely tetrahedral framework as in zeolites. Heteropolyhedral compounds have been extensively studied since the early 1990's, with particular attention having been focused on titanosilicates, such as ETS-4 (synthetic analog of the mineral zorite) and ETS-10. However, titanosilicates are not the only representatives of novel microporous mineral phases. The search for "octahedral"-tetrahedral silicates was extended to metals other than titanium, for instance, the zirconosilicates with the preparation of synthetic counterparts of the minerals gaidonnayite, petarasite and umbite. Many microporous heteropolyhedral compounds containing metals such as Nb, V, Sn, Ca and lanthanides, have been reported and a wide number of distinct structural types (e.g., rhodesite-delhayelite and tobermorite) have been synthesized and structurally characterized. Moreover, the potential applications of these novel materials have been evaluated, particularly in the areas of catalysis, separation of molecular species, ion exchange and optical and magnetic properties. A comprehensive review of the mineralogical, structural, chemical and crystal-chemical studies carried on natural phases may be extremely useful to inspire and favor investigations on analogs or related synthetic materials. A similar synergy between mineralogists and materials scientists already occurred in the "classical" case of zeolites, in which the wide and deep structural and crystal-chemical knowledge accumulated in the study of the natural phases was extraordinarily useful to the chemists who are active in the field of molecular sieves. In particular, the structural investigation of the natural phases may be extremely rewarding and helpful in orienting the work of synthesis and in understanding the nature of the synthetic products, for the following reasons: Whereas rarely the crystalline synthetic products are suitable for single-crystal structural investigations, the natural counterparts are often well crystallized. Crystallization in nature occurs from chemical systems characterized by a wide compositional range, thus producing compounds with a very rich and variable crystal chemistry, which may provide precious information, suggesting possible substituting elements and addressing the synthetic work in a very productive way. The present volume follows a meeting on "Micro- and mesoporous mineral phases" (Rome, December 6-7, 2004) that was jointly organized by the Accademia Nazionale dei Lincei (ANL) and the International Union of Crystallography (IUCr) via its Commission on Inorganic and Mineral Structures (CIMS). The meeting was convened by Fausto Calderazzo, Giovanni Ferraris, Stefano Merlino and Annibale Mottana and financially supported by several other organizations representing both Mineralogy (e.g., the International Mineralogical Association and the European Mineralogical Union) and Crystallography (e.g., the European Crystallographic Association and the Italian Association of Crystallography). To participants, ANL staff, organizations, and, in general, all involved persons, our sincere acknowledgments; in particular, we are grateful to Annibale Mottana who was able to convince the ANL Academicians to schedule and support the meeting. This volume of the RiMG series highlights the present knowledge on micro- and mesoporous mineral phases, with focus on their crystal-chemical aspects, occurrence and porous activity in nature and experiments. As zeolites are the matter of numerous ad hoc meetings and books - including two volumes in this series - they do not specifically appear in the present volume. The phases of the sodalite and cancrinite-davyne groups, which mineralogists consider distinct from zeolites, are instead considered (in the order, chapter 7 by W. Depmeier and part of chapter 8 by E. Bonaccorsi and S. Merlino, respectively). The first two chapters of the volume cover general aspects of porous materials. This includes the application of the IUPAC nomenclature developed for ordered porous materials to non-zeolite mineral phases (L.B. McCusker, chapter 1) and the extension to heteropolyhedral structures of a topological description by using nodes representing the coordination polyhedra (S.V. Krivovichev, chapter 2). Chapters from 3 to 7 are dedicated to various groups of heteropolyhedral porous structures for which the authors emphasize some of the more general aspects according to their research specialization. G. Ferraris and A. Gula (chapter 3) put the emphasis on the modular aspects of well-known porous phases (such as sepiolite, palygorskite and rhodesite-related structures) as well as on heterophyllosilicates that may be not strictly porous phases (according to the definition given in chapter 1) but could be the starting basis for pillared materials. The porous mineral phases typical of hyperalkaline rocks (such as eudialytes and labuntsovites) are discussed by N.V. Chukanov and I.V. Pekov under their crystal-chemical (chapter 4) and minerogenetic (chapter 5) aspects showing the role of ion exchange during the geological evolution from primary to later phases, with experimental cation exchange data also being reported. J. Rocha and Z. Lin (chapter 6) emphasize how research on the synthesis of octahedral-pentahedral-tetrahedral framework silicates has been inspired and motivated by the many examples of such materials provided by nature; synthesis, structure and possible technological applications of a wide number of these materials are also described. Following chapters 7 and 8 - which besides the cancrinite-davyne group, presents the crystallographic features of the minerals in the tobermorite and gyrolite groups - M. Pasero (chapter 9) illustrates the topological and polysomatic aspects of the "tunnel oxides," a historical name applied to porous oxides related to MnO2, and reviews their main technological applications. The next two chapters (10 and 11) draw attention to "unexpected" porous materials like apatite and sulfides. T.J. White and his team (chapter 10) convincingly show that the apatite structure type displays porous properties, some of which are already exploited. Chapter 10 also contains two appendices that report crystal and synthesis data for hundreds of synthetic apatites, a number that demonstrates how wide the interest is for this class of compounds. E. Makovicky (chapter 11) analyzes the structures of natural and synthetic sulfides and selenides showing that, even if experimental work proving porous activity is practically still missing, several structure types display promising channels. Chapter 12, by M. Mellini, is the only one dedicated to mesoporous mineral phases - which are crystalline compounds with pores wider than 2 nm. Examples discussed are carbon nanotubes, fullerenes - which occur also in nature - chrysotile, opal and, moving from channels to cages, clathrates.

Description / Table of Contents: This volume contains the contributions presented at a short course held in Golden, Colorado, October 25-27, 1996 in conjunction with the Mineralogical Society of America's (MSA) Annual Meeting with the Geological Society of America in Denver, Colorado. The field of reactive transport within the Earth Sciences is a highly multidisciplinary area of research. The field encompasses a number of diverse disciplines including geochemistry, geology, physics, chemistry, hydrology, and engineering. The literature on the subject is similarly spread out as can be seen by a perusal of the bibliographies at the end of the chapters in this volume. Because these distinct disciplines have evolved largely independently of one another, their respective treatments of reactive transport in the Earth Sciences are based on different terminologies, assumptions, and levels of mathematical rigor. This volume and the short course which accompanies it, is an attempt to some extent bridge the gap between these different disciplines by bringing together authors and students from different backgrounds. A wide variety of geochemical processes including such diverse phenomena as the transport of radiogenic and toxic waste products, diagenesis, hydrothermal ore deposit formation, and metamorphism are the result of reactive transport in the subsurface. Such systems can be viewed as open bio-geochemical reactors where chemical change is driven by the interactions between migrating fluids, solid phases, and organisms. The evolution of these systems involves diverse processes including fluid flow, chemical reaction, and solute transport, each with differing characteristic time scales. This volume focuses on methods to describe the extent and consequences of reactive flow and transport in natural subsurface systems. Our ability to quantify reactive transport in natural systems has advanced dramatically over the past decade. Much of this advance is due to the exponential increase in computer computational power over the past generation-geochemical calculations that took years to perform in 1970 can be performed in seconds in 1996. Taking advantage of this increase of computational power, numerous comprehensive reactive transport models have been developed and applied to natural phenomena. These models can be used either qualitatively or qualitatively to provide insight into natural phenomena. Quantitative models force the investigator to validate or invalidate ideas by putting real numbers into an often vague hypothesis and thereby starting the thought process along a path that may result in acceptance, rejection, or modification of the original hypothesis. Used qualitatively, models provide. insight into the general features of a particular phenomenon, rather than specific details. One of the major questions facing the use of hydrogeochemical models is whether or not they can be used with confidence to predict future evolution of groundwater systems. There is much controversy concerning the validity and uncertainties of non-reactive fluid flow systems. Adding chemical interaction to these flow models only confounds the problem. Although such models may accurately integrate the governing physical and chemical equations, many uncertainties are inherent in characterizing the natural system itself. These systems are inherently heterogeneous on a variety of scales rendering it impossible to know precisely the many details of the flow system and chemical composition of the host rock. Other properties of natural systems such as permeability and mineral surface area, to name just two, may never be known with any great precision, and in fact may be unknowable. Because of these uncertainties, it remains an open question as to what extent numerical models of groundwater flow and reactive transport wilI be useful in making accurate quantitative predictions. Nevertheless, reactive transport models should be able to predict the outcome for the particular representation of the porous medium used in the model. Finally, it should be mentioned that numerical models are often our only recourse to analyze such environmental problems as safe disposal of nuclear waste where predictions must be carried out over geologic time spans. Without such models it would be impossible to analyze such systems, because they involve times too long to perform laboratory experiments. The results of model calculations may affect important political decisions that must be made. Therefore, it is all the more important that models be applied and tested in diverse environments so that confidence and understanding of the limitations and strengths of model predictions are understood before irreversible decisions are made that could adversely affect generations to come.

Description / Table of Contents: Since the dawn of life on earth, organisms have played roles in mineral formation in processes broadly known as biomineralization. This biologically-mediated organization of aqueous ions into amorphous and crystalline materials results in materials that are as simple as adventitious precipitates or as complex as exquisitely fabricated structures that meet specialized functionalities. The purpose of this volume of Reviews in Mineralogy and Geochemistry is to provide students and professionals in the earth sciences with a review that focuses upon the various processes by which organisms direct the formation of minerals. Our framework of examining biominerals from the viewpoints of major mineralization strategies distinguishes this volume from most previous reviews. The review begins by introducing the reader to over-arching principles that are needed to investigate biomineralization phenomena and shows the current state of knowledge regarding the major approaches to mineralization that organisms have developed over the course of Earth history. By exploring the complexities that underlie the "synthesis" of biogenic materials, and therefore the basis for how compositions and structures of biominerals are mediated (or not), we believe this volume will be instrumental in propelling studies of biomineralization to a new level of research questions that are grounded in an understanding of the underlying biological phenomena.

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.