314 Book reviews Geochemical rate models, by J. Donald Rimstidt, 2014. Cambridge University Press, Cambridge, United Kingdom (order through http://www.cambridge.org/nl/academic/subjects/earth-and-environmental-science/geochemstry-and-environmental-chemistry/geochemical-rate-models-introduction-geochemical-kinetics). 239 pages. Hardcover: price GBP 45.00, ISBN 978-1-107-02997-2; E-Book: price USD 60.00, ISBN 978-1-107-59643-6. Deep insights into Earth systems have been gained from the use of thermodynamic principles in the modelling of geological processes. However, although equilibrium thermodynamics allows to reveal the end-point of a process, it does not predict when this will happen and what is the exact course of the reaction. Time is a fundamental variable in kinetics, but not in thermodynamics. Geochemical rate models concern the course of time of natural processes and are the essentials of geochemical kinetics. Basically, geochemical rate models are based on macroscopic observations; however, molecular kinetics also provides insights into the subject. Kinetic theories and rate models concern all possible Earth systems, starting from near-surface aqueous environments, through magma chambers, to high-temperature and high-pressure solids in the Earth’s interior. The present book discusses only low-temperature processes in aqueous systems because these are commonly far removed from equilibrium and can be adequately modelled only with tools delivered by geochemical kinetics. The spatial and temporal patterns of natural processes in Earth systems often are complex, and even seem to be chaotic. The strategy to understand such systems is to model simple processes, and then to try to link them into larger fragments. The book reviewed here provides tools for modelling and interpreting such simple processes. Each chapter contains theoretical background, where possible shown as mathematical expressions, which is interwoven with examples from natural systems. These examples are presented in ‘Example boxes’, which are successive problems solved in an easy-to-follow way, and frequently summarised by a more general conclusion. Not only does the author emphasise the meaning of a single model, he also warns against overinterpretation of results of experiments and shows possible pitfalls. Simple black-and-white illustrations make the text more comprehensive. A large part of the examples is taken from the models worked out by the author himself, such as silica-water reactions, oxidation of pyrite and forsterite dissolution. Undoubtedly, they do not include all possible reactions that occur in near-surface environments. Rather, they were chosen as well-understood processes, studied in depth by the author. Modelling tools are explained at the start, in Chapter 2, and include regression models and numerical differentiation. Centre stage is for rate equations, which are expressed in several ways from the time derivative of the number of moles of chemical species formed or consumed, to the time derivative of the extent of reaction, and presented for unopposed (one-way, forward) reactions and for various types of opposed reactions. The coverage of the book includes also the concept of ideal chemical reactors as an introduction to experimental kinetics (Chapter 4); molecular kinetics in the form of general physicochemical processes, and particularly the conceptual basis of transition-state theory (Chapter 5); surface kinetics as a tool of understanding some aspects of mineral dissolution and growth (Chapter 6); diffusion and advection and their influence on chemical reaction rates (here, dimensionless numbers are introduced to describe the two competing processes (Chapter 7)); quasi-kinetics assuming local equilibrium, as for reaction path models (Chapter 8); accretion and transformation kinetics describing multistep solid crystallisation from supersaturated solutions (Chapter 9). Additionally, each chapter is supplemented by online resources, Book reviews freely available at www.cambridge.org/rimstidt, consisting of problems to be solved and examples of solutions in Excel sheets. The examples are not trivial; they contain data from papers published in Geochemica et Cosmochimica Acta. The great achievement of the present book is its clarity. Donald Rimstidt, currently Professor Emeritus of Geochemistry at Virginia Polytechnic Institute and State University, USA, has a wide experience in teaching geochemistry, and the effort of making understood problems by explaining them as best as possible underlies the entire volume. Successive topics are presented either as (relatively) simple mathematical models, always accompanied by examples of common, real-world processes, or merely mentioned briefly with reference to relevant textbooks or papers. Carefully chosen and up-todate references are another advantage. Since geochemical kinetics is anchored in chemical kinetics and derives from the achievements of chemical engineering, mineral processing, and soil sciences, the reference list itself may be treated as a guide in classic and modern texts in (geo)chemical kinetics. 315 A distinguishable feature of the book is the importance placed on the use of consistent terminology and notation. This is clearly expressed in first chapters but repeated in many places throughout the text, so that none of readers are lost even if they start reading from the middle of the book. The subtitle, An introduction to geochemical kinetics, clearly indicates that not all aspects of geochemical kinetics are covered equally. Indeed, the book is not voluminous, which encourages self study by students interested in the subject. In summary, this book is a must-read for students who are interested in the rates of geochemical low-temperature processes and their quantitative models, and who try to use this knowledge in designing experiments or for explaining experiment observations. The book may be also useful for more advanced researchers so as to ‘refresh their memories’, as a teaching aid, and to inspire future research. Julita Biernacka Adam Mickiewicz University, Poznań, Poland julbier@amu.edu.pl