According to the literature, a number of approaches can be used to study pyrite oxidation. They include a) inorganic/biochemical reaction approaches, b) electrochemical reaction approaches and b) reaction kinetics approaches. Each of these approaches may reveal some information with respect to pyrite oxidation, but all approaches are to some degree interrelated on interdependent. For example, under kinetic approaches one is interested in finding out, under certain controlled conditions, the rate at which certain chemical species are produced (biotically or abiotically). These controlled conditions, however, are described by the redox-state and the chemical state of the oxidizing system. If during kinetic oxidation experiments electron poor ions are produced, e.g., Fe(III) or Mn(III) or Mn(IV), then the complexity of the oxidizing system will be changing (see Chapter 6). Also, as oxidation proceeds and products accumulate in the reaction environment, the chemical-oxidation status of the system will be changing due to chemical complexation taking place between the chemical species produced (see Chapter 1). Thus, the study of pyrite oxidation is a rather complex process because one can not separate kinetic processes from electric processes and/or from chemical processes, inorganic or biological in nature.