ABSTRACT
This chapter discusses that the pyrite oxidation in the natural environment is a surface controlled reaction and for this reason pyrite oxidation under such conditions may never come to completion. Pyrite oxidation models can be grouped into two categories depending on approach employed to make predictions: deterministic functional models, and mechanistic models. In nature, acid drainage is a product of pyrite oxidation or perhaps oxidation of various other unstable metal sulfides. The two major forms of iron-disulfide in geologic strata are pyrite and marcasite. The structure of marcasite is orthorhombic while that of pyrite is isometric. Because of its particular structure, marcasite is less stable than pyrite. Pyrite is generally associated with coal fields in the United States and elsewhere in the world. Pyrite can vary significantly in grain size and morphology, depending on the environment of formation. Acid-base accounting is the most widely used method for characterizing overburden geochemistry because it is simple, relatively inexpensive, and reliable.
