This book recounts the development of experiment and theory in natural particle surface chemistry over the past 20 years. It offers a broadly based discussion of molecular spectroscopy, kinetics, and equilibria as they apply to natural particle surface reactions in aqueous media, with emphasis on insights gained over the past few years. After a review of qualitative notions about ion adsorption by natural particles, the strategies and theory of four spectroscopic approaches to studying natural particles are described, current models of surface chemical kinetics and equilibria are examined, and natural particle colloidal phenomena are detailed. Discussion is accompanied by lengthy annotations and reading suggestions, and punctuated by end-of-chapter problem sets that require a critical reading of important technical journal articles.