Intended as an introduction to geochemistry - an increasingly important part of earth science, this book emphasizes the application of geochemistry to geologic problems - presenting carefully selected examples from actual field and laboratory studies. The book's goal is to make readers come to understand geochemistry as an exciting area of research, and to provide a feeling for the usefulness of geochemistry as a background for many kinds of earth science inquiry. Throughout the book, attention is continually directed to the relations between theoretical formulas and results of controlled laboratory experiments, as well as to geologic field observations. The book begins with an introduction to chemical equilibrium, concentrating on the carbonate and silicate equilibria that are important in geologic environments. Next comes a brief look at the chemistry of crystalline solids and reactions at mineral surfaces. The manifold uses of isotopes in geochemistry are given extended treatment, and the recent important studies of reaction rates and mass transfer are covered. Readers will then find detailed discussions of the geochemistry of materials at and near the earth's surface.