Abstract This CMS Workshop Lecture Series (WLS) volume is intended to give a summary of the current state-of-the-art of different spectroscopy and microscopy methods, as presented during a workshop held in conjunction with the EUROCLAY 2015 conference in Edinburgh, UK, on the 5th of July 2015. This workshop was initiated by the NEA Clay Club, The Clay Minerals Society, and the Euroclay conference series. This EUROCLAY 2015 workshop is a continuation of the very successful workshop “Clays under Nano- to Microscopic resolution” which took place from 6 th to the 8 th of September 2011 in Karlsruhe and documents new developments and the progress made over the past four years concerning research in low-permeability, clay-rich, geological formations. The workshop also provided an excellent opportunity for exchange of knowledge with research communities concerned with the safe long-term management of radioactive waste within argillaceous sediments, and with shale gas and oil exploration.

Abstract The one day workshop on which this volume was based focused on the development and use of advanced materials based on clays, and it was attended by well over 100 participants who were closely engaged with the speakers and participated in active question/answer and discussion sessions. The papers collected in this volume represent some of the most outstanding research presented at the workshop and each represents an exciting step forward in the development and integration of clay minerals into active and functional materials.

Abstract This volume presents the majority of topics in synchrotron science that are of use to the clay science community. The chapters presented in this volume serve not only as significant statements on the state of these applications, but also as useful primers to potential new users of synchrotron facilities.

Abstract The beauty and lure of Yellowstone National Park (YNP) to visitors from all around the world, in large part, comes from one of the very things that gives it its own name; The bright and colorful clay-sized mineral assemblage that make up its grand mountains, alluring valleys and brilliant hot springs. Proximity of The Clay Minerals Society (CMS) 2009 annual meeting to one of the largest terrestrial geothermal area in the world was ample reason to run the first “inquiry-based” CMS Workshop Lectures series (WLS), where both lectures and field excursions were emphasized. Inquiry teaching is investigating with questions, emphasizing evidence, forming explanations, making connections to the larger scientific community, and communicating conclusions. This accompanying volume brings another first to the CMS-WLS, which is electronic formatting and the benefit of color graphics, where a picture is worth a 1000 words. This volume includes displays and maps designed to bring the reader closer to YNP and perhaps let them better virtually sense the heat of hot springs, the smell of fumaroles, the sounds of gushing geysers, and the panorama of colors. This CMS-WLS also joins the mainstream realization that most Earth surface mineralization processes are mediated in the presence of biological communities. In fact, it may be harder to find an exception than a rule to this understanding. Microbiological metabolic pathways that exchange protons, electrons, and essential ions in nature are inextricably linked to clay sized mineral reaction pathways that do the same. For example, the reduction of iron in a smectite-bearing hot spring may be linked to the oxidation of N in a microbe (and visa versa). To understand the patterns that shape the clays and clay minerals we see today in YNP, one must embrace both the caldera-scale range of igneous, glacial, and hydrological processes, as well as the atomic-scale processes that occur along steep redox, pH, anions, cations, and temperature gradients. To this end, this CMS-WLS volume is holistically designed to cover (1) broad scale features of YNP as seen by remote sensing technology, (2) the evidence and processes by which biomineralization of clay sized materials occurs within terrestrial hot springs, and (3) the importance of spring chemistry, microbial communities, and other coexisting clay-sized, but non-clay mineral phases that are present. These perspectives lead to better understanding of the occurrences and variations of clay mineral assemblages existing within the environs of YNP and perhaps their analogs on early Earth and other planets.

Abstract Organic matter (OM) in soil plays vital roles with respect to global climate change, as the largest terrestrial reservoir of organic carbon, and with respect to soil quality through the stabilization of soil structure and the retention and cycling of plant nutrients. The interactions between lay minerals and OM are central to most of these functions. Clays may catalyze formation of new humic substances, inhibit the degradation of existing humic substances through physically sequestration, and clay-humic associations are at the very heart of aggregation and soil structure stabilization. In this book we seek to explore the state of knowledge related to these topics and the analytical tools used to investigate them. In chapter 1, Hayes et al. describe chemical fractionation techniques and relate clay bound soil OM to the “humin” fraction. Chen and arcjotzly (Chapter 2) discuss the role of humic substances and polysaccarides in formation and stabilization of soil structure. Gonzalez (Chapter 3) considers the potential catalytic role of clays in the formation of new humic materials. Wershaw (Chapter 4) considers the nature of soil OM and clay-humic complexes as revealed by NMR and other techniques. The last two chapters, Chenu et al. (Chapter 5) and Laird and Thompson (Chapter 6), focus directly on understanding the nature of clay-humic complexes as revealed by electron microscopic techniques. It is hoped that this volume will provide the reader with both advanced understanding of the current state of knowledge and an appreciation for the gaps in that knowledge. The knowledge gaps represent challenges for future generations of scientists.

Abstract As is well established in these reviews, CPN research is a complex subject that is both timely and developing rapidly. While the term “polymer-clay nanocomposite” is more conventional in the literature, the term CPN is employed in this volume in order to stress the importance of the clay science. The number of publications on CPN has increased exponentially since the first Toyota report and patent for clay mineral nylon-6 nanocomposites, although surprisingly their commercial applications are comparatively rare. This may be partly because a broad description of the processing-morphology/structure properties complex relationship is still lacking. The variations of layered filler, organic modifier, polymer matrix, processing parameters and characterization methods, leave endless combinations for study. In the voluminous published literature, one often finds contradictory materials behavior. It is becoming apparent that morphological effects are absolutely crucial to properties, but this is a parameter that is difficult to quantify experimentally.

Abstract Microorganisms are implicated in a wide array of geochemical processes of importance to the clay sciences; a point that is highlighted in special issues of journals such as Geochimica et Cosmochimica Acta (2004, Vol. 68, no. 15) and Clays and Clay Minerals (2005, Vol. 53, no 6). Life and geochemistry often overlap at the micron scale; i.e., that of a clay mineral, as organisms seek energy and substrates on which to exist and grow. Organisms can only work within the realm of thermodynamic reality. However, as is becoming increasingly evident, the ability of microorganisms to affect fundamental parameters such as pH and redox potential and to strongly affect reaction kinetics can be tied to ecological factors, most likely involving complex feedback.

Abstract It has been nearly 30 years since two of the most influential books were published on infrared spectroscopy on minerals by Farmer and on clay minerals in particular by van der Marel and Beutelspacher. Since then much has changed in terms of technology, such as the development of Fourier Transform infrared spectroscopy, and the development of new vibrational spectroscopic techniques for the study of minerals. Clays have formed and still form a very important part of our economy and it is thus not unreasonable to expect that this is reflected in the research applying vibrational spectroscopy to study clay minerals. However, all these developments are spread over a large amount of literature and a book reviewing these developments is lacking. I hope that this book will be able to fill this gap. Major developments in the use of mid- and near-infrared to study the structure of clays modified clays, the use of Raman spectroscopy to study clays and their intercalation and the use of infrared emission spectroscopy to study thermal processes have resulted in a CMS workshop lecture volume in which a unique set of overviews in this specialized field of research, on a level that can be appreciated by all to whom clay science is dear, is brought together.

Abstract Somewhere between the ideas that we can calculate everything about chemical systems and that everything coming out of a computer is nonsense, lies the truth about molecular modeling. In essence, we might be able to calculate everything, if we could solve the Schrödinger equation for macroscopic size systems. However, numerous approximations to the full Schrödinger equation are generally made in even the most sophisticated quantum mechanical calculations. Furthermore, the size of simulated systems does not even approach one mole of a substance, to say nothing of a complex geochemical system of solution and minerals. Limitations, such as these, should not discourage the use of molecular modeling techniques in geochemistry, soil science, catalysis or other disciplines interested in clay structure and chemistry. Judicious choice of model systems and techniques allow a great deal of useful information to be extracted from a "computer experiment." In this volume we outline a variety of techniques that can be employed to address different types of chemical questions and demonstrate through examples what types of answers we can expect.

Abstract The articles in this text have been assembled to give readers an idea of the large number of research possibilities associated with combining electrochemical methods with clay research. The first article is introductory in nature. It describes the common features of the diffuse double layer that intrigue clay chemists and electrochemists alike. Based on this common understanding it develops the flux equations that underpin all electrochemical experiments and ends by describing experimental details that the beginning electrochemists should be aware of when attempting to apply electrochemical methods to clays. The group of Fitch gives extensive review to applications of clay-modified electrode work in understanding flux of materials in clay films. At the workshop Dr. Janet Osteryoung presented the use of electrochemical methods, such as microelectrode cyclic voltammetry, in elucidating the charge of colloids. Dr. Osteryoung, at the time head of the NSF division of Chemistry, was unable to write an article, however the technique is extensively reviewed in the first article. The technique relies upon the difference in diffusion coefficient of a cation distributed between the diffuse double layer of a colloid and the bulk solution can be used to determine the distance between charges on the colloid. The first article also attempts to set the clay-modified electrode context for each of the other submissions in this volume: Yamagishi, Manias, Amonette, and Villemure. The use of clay-modified electrodes is detailed, particularly for the information it can give on diffusion in composite materials (see the article of Prof. Aki Yamagishi, now of the University of Tokyo). One of the problems with clay-modified electrodes has been in the structure of the films obtained and the thickness of those films. Yamagishi presents results using Langmuir Blodgett clay film formation using surfactants. Those clays films are then used in clay-modified electrodes to determine intrinsic electroactivity of very thin clay films. Along the same lines recent researchers are interested in the flux of both electroactive and electroinactive materials in nanocomposites of clays. One exciting area is that of polymer composites which are designed to give high sodium or potassium flux and good stability at relatively high temperatures. These membranes can be used in developing the next generation of fuel cells. The conductivity of such films exposes an interesting theoretical and experimental problem. E. Manias, A.Z. Panagiotopoulos, D.B. Zax and E.P. Giannelis of the Departments of Materials Science and Engineering, Chemical Engineering, and Chemistry and Chemical Biology, Cornell University review some of the theoretical work which attempts to elucidate the mechanisms by which high sodium flux occurs in these nanocomposites. The introductory article by Susan Macha, Scott Baker, and Alanah Fitch of Loyola University Chicago covers some of the experimental electrochemical techniques used to determine the conductivities of these clay nanocomposite films. Another exciting area of application of electrochemistry to problems in clay chemistry is in the area of the direct reduction and oxidation of redox metals in clay crystals. This work is of practical interest because of its potential application to remediation of contaminated military sites. It is known that clay interceptor beds that are reduced with dithionite serve to control contaminant plumes. James E. Amonette of Pacific Northwest Labs gives a review of the reactivity of iron in clay minerals. This review is followed by an article by Prof. Gilles Villemure of University of New Brunswick, Canada, which shows some of the most successful electrochemical experiments involving direct reduction of metals in clay lattices.

Abstract The teaching of clay science is often thought of as forming the curriculum of an upper-level college course for juniors, seniors and graduate students. Although clays and clay minerals are complex subjects often requiring extensive background to understand in detail, introducing topics related to clays does not require such specialization. Furthermore, clays are a part of modern everyday life, being found in common household products (from toothpaste, toilets, and cat litter to paper, plastics, and fine china). It does not seem reasonable to wait until a student reaches the upper-college level to introduce the subject, although the introduction of clay science must be approached at levels appropriate to the student's development and background. In fact, one of us (A. Rule) has successfully introduced crystallography concepts of crystal shape and symmetry, and has taught lessons in the industrial uses of clay minerals at the primary-school level. Education scholars have developed procedures for teaching that closely parallel the way humans learn. For the most part, these instructional practices have not been implemented at the college level, although such teaching methods could easily be applied to benefit college-level students. The idea of a Teaching Clay Science Workshop was developed over the last three years to integrate the efforts of education scholars, high-school teachers and college professionals toward improving clay-science instruction. This integration of learning theory with clay-science teaching has produced a unique set of example lessons, which resulted in this volume of Workshop Lectures. Finally, we express our appreciation to P. Schroeder for taking our edited manuscripts and organizing them to conform to the CMS Workshop Lectures Series. Also, we thank M. Krekeler for working through all of the laboratories presented here and for providing his comments to the authors.

Abstract Contamination of soils and sediments with organic chemicals and the potential movement of these chemicals to ground water are of increasing public concern. Because of their large surface area and charge, clays comprise the most important inorganic component in controlling the fate and transport of organic chemicals entering soils and sediments. It is essential, therefore, to understand interactions of organic pollutants with clays. The chapters in this volume consider the roles of clays in sorption, transport, attenuation, and bioremediation of organic pollutants in contaminated systems.

Abstract Layer charge is recognized as the single most important characteristic of 2:1 phyllosilicates. It indicates a mineral's capacity to retain cations and to adsorb water and various polar organic molecules. The affinity of organic-clays for sorption of organic contaminants in aqueous systems is now attracting considerable attention. The layer charge is also considered an important criterion for the classification of 2:1 silicate clay minerals. It is generally agreed that the magnitude of the layer charge can be taken into account to resolve the classification problem. Studies on structural chemistry also confirm the importance of layer charge for characterization of silicate clays.”

Abstract A set of surface-sensitive analytical techniques, collectively called scanning probe microscopy (SPM), has been developed and applied to a wide variety of materials. With SPM one can image nearly any surface in vacuum, in air, or in solution, and often can actually observe surfaces during reaction. Scanning tunneling microscopy (STM) and scanning force microscopy (SFM) have been used successfully in the geosciences to characterize mineral surface structure and topography, surface reactivity, and the rates and mechanisms of mineral-water reactions. SPM techniques are most easily applied to materials with nearly flat surfaces, and minerals with good cleavage, particularly clays, which are excellent prospects for investigation. However, there have been relatively few applications of SPM to geologic materials, particularly in comparison to applications in physics, chemistry, material science, or even biological sciences. The purpose of this volume is to introduce the theory and operation of SPM to clay mineralogists, summarize previous work using STM and SFM in mineralogy, and outline the advantages and limitations of SPM for future research applications.

Abstract The advent of high-speed desk-top computers has made it possible to solve many crystallographic problems which heretofore required long hours of calculating. More importantly, many problems can be addressed that were simply inaccessible by any means thirty years ago. Some of the programs described in this volume complete more calculations in minutes than an individual could accomplish over a lifetime even if every second of that lifetime was spent with pencil and paper in hand. And the necessary computing tools are widely available at prices comparable to two or three of the best slide rules in the 1950's. We do routinely what could not have been imagined by scientists of a few generations ago. And this is just the beginning-we will do Rietveld analyses some day on laptop computers that will be disposed of when their batteries run down.

Abstract Kaolin is an important industrial mineral in several world markets including uses in paper coating and filling, ceramics, paint, plastics, rubber, ink, fiberglass, cracking catalysts and many other uses (Murray, 1991). The kaolin minerals kaolinite, halloysite, dickite, and nacrite have essentially similar chemical composition but each has important structural and stacking differences. The most common kaolin mineral and the one that is the most important industrially is kaolinite [Al2Si205(OH)4]. Kaolinite can be formed as a residual weathering product, by hydrothermal alteration, and as an authigenic sedimentary mineral. The residual and hydrothermal occurrences are classed as primary and the sedimentary occurrences as secondary. Primary kaolins are those that have formed in situ usually by the alteration of crystalline rocks such as granites and rhyolites. The alteration results from surface weathering, groundwater movement below the surface or action of hydrothermal fluids. Secondary kaolins are sedimentary which were eroded, transported and deposited as beds or lenses associated with other sedimentary rocks. Most kaolin deposits of secondary origin were formed by the deposition of kaolinite which had been formed elsewhere. Some secondary deposits were formed from arkosic sediments that were altered after deposition, primarily by groundwater. There are far more deposits of primary kaolins in the world than secondary kaolin deposits because special geologic conditions are necessary for both the deposition and preservation of secondary kaolins.

Abstract Rheology is the science of the flow of fluids and deformation of solids. Of special interest to the clay scientist are the flow behavior and stability of clay suspensions, and the time-dependent deformation of clays in a solid or semi-solid state. The physical state of a clay may change with increasing water content; from a solid, to a semi-rigid plastic, then to a gel, and finally to a suspension. In each state, the main factors determining the rheological behavior of the system are related to: (a) the molecular configuration and dynamics of the clay-water interface, and (b) the nature of the particle interactions at this interface. The hydration of the ions and the clay surfaces plays a special role in clay rheology because flow and deformation directly involve molecular movements along the clay-water interface.