The study of the geochemistry and mineralogy of different size fractions is essential to understanding mobility and availability of minerals to dissolution and oxidation during the weathering processes that takes place in mine rock pile materials. The oxidation results in acidic, iron- and sulfate-rich waters, which accelerate the oxidation of rock-forming minerals. This book, therefore, provides insight on: 1) how the amount and the extent of oxidation of the sulfide minerals vary from rock piles to rock piles all around the world due to different mineralogies and geochemical properties and 2) characterization of the geochemical and mineralogical properties of bulk rock pile samples and their different grain size fractions. At the end of reading this book you will come to understand how acid mine drainage could be tackled from a single understanding of the mineralogy and geochemistry of particle size fractions of mine rock pile materials.