Principles and applications of geochemistry 2nd Edition

Author Faure, Gunter
Title Principles and applications of geochemistry : a comprehensive textbook for geology students
Place of Publication Upper Saddle River, N.J.
Publisher Prentice Hall
Publication year 1998
Sub-type Other
Open Access Status
Edition 2nd
ISBN 0023364505
Language eng
Total number of pages 600
Formatted Abstract/Summary
Preface

This textbook is intended as an introduction to geochemistry for geology students in their senior year or in their first year of graduate work. At that time in their education, students are ready to re/earn those principles of chemistry that are especially applicable to the study of geological processes. Geochemistry can enhance their understanding of these processes and can teach them to apply principles of chemistry to the solution of geological problems. Geologists in virtually all branches of the science can benefit from an introductory course in geochemistry because it can help them to make quantitative predictions about the outcome of chemical reactions that occur in the context of many geological processes.

The subject matter of this book is presented in five parts. Part I: Planet Earth in the Solar System (Chapters 1 through 4) presents the big picture starting with the Big Bang, stellar evolution, nucleosynthesis, the solar system, and the geochemistry of the Earth. This part also contains a brief history of geochemistry leading up to a statement of its goals and stating the theme of this book: Studies of geochemistry convert idle speculation into understanding.

The second part, Principles of Inorganic Geochemistry (Chapters 5 through 8), starts with the electronic structure of atoms and demonstrates how wave mechanics and the Aufbau principle lead directly to the periodicity of the chemical properties of the elements. Once the periodic table has been constructed, systematic variations in bonding, ionic radii, and the structure of crystals become apparent, thus preparing the way for a discussion of ionic substitution based on the rules of Goldschmidt and Ringwood. Part II concludes with discussions of coupled substitution in feldspar, distribution coefficients, and the geochemical classification of the elements.

Part III is entitled Aqueous Geochemistry and the Stability of Minerals (Chapters 9 through 15). These chapters explain the concept of chemical equilibrium and use the Law of Mass Action to study the dissociation of weak acids and bases and to calculate the solubility of amorphous silica as a function of the pH. Next, the dissociation of salts, the hydrolysis of their ions, and the necessity of using the activities of ions rather than their molal concentrations in Mass Action problems are presented. All of these concepts come into play in the carbonate equilibria involving calcite, its ions in aqueous solution, and C02 in the atmosphere. However, the incongruent dissolution of microdine to form koalinite plus ions leads to an impasse because the value of the equilibrium constant for that reaction has not been measured.

Therefore, Chapter II contains a guided tour of the principles of thermodynamics leading up to a derivation of the Law of Mass Action for reacting mixtures of ideal gases at equilibrium. In addition, this chapter demonstrates that equilibrium constants at the standard temperature and pressure can be calculated from the Gibbs free energy change of chemical reactions. This skill is immediately used to construct ion-activity diagrams for aluminosilicate minerals including zeolites (Chapter 12) and clay minerals (Chapter 13).

Finally, oxidation-reduction reactions are introduced in Chapter 14, and the previously acquired knowledge of thermodynamics is used to explain some basic principles of electrochemistry. These insights are then used to define the stability limits of water on the Earth and to construct Eh-pH diagrams for the oxides of iron and their ions. Chapter 15 deals with the kinetics of chemical reactions, and with the transport of ions by diffusion and advection. These concepts are used to model the growth of concretions during diagenesis and the formation of monomineralic layers at the sediment-water interface. ……………………

Keyword Geochemistry