Microbial controls on the mineralogy of the environment

Microbes have a dramatic impact on the mineralogy of the environment as a result of their metabolic processes. Microorganisms can control both acidity and redox chemistry as a result of respiration, photosynthesis, chemoautotrophy or anaerobic respiration. The net impact of these biogeochemical reactions can result in formation of minerals that have distinctive 'bulk' and surface chemical characteristics, morphology and trace element or isotopic composition that is distinct from those produced abiotically. This chapter describes several examples of both direct and indirect biomineralization including the role of neutrophilic and acidophilic iron oxidizers on the biogeochemistry of Fe minerals in two mine sites, the role of microbial metabolic processes on mineral weathering and nutrient cycling, and the enhanced mobility and enrichment of economically important trace elements such as zinc, gold and the rare earth elements