- © The Mineralogical Society Of America
Organisms that live on and near the surface of the Earth affect the cycling of sulfur and metals and thus the formation and decomposition of sulfide minerals. Biological mediation of mineral formation can take many forms. Some organisms have evolved to synthesize minerals that are used for a particular function, such as structural support, protection against predators, hardening, or magnetic sensing. In these cases, the organism exerts strict control over the properties and the location of the mineral. The process by which such minerals form is termed biologically controlled mineralization (BCM) (Lowenstam and Weiner 1989).
Biominerals can also form as a byproduct of the metabolism of organisms, or as a consequence of their mere presence. Life can create chemical environments that result in the precipitation of minerals, and biological surfaces can serve as nucleation sites for mineral grains. In such cases, the adventitious deposition of minerals is termed biologically induced mineralization (BIM) (Lowenstam and Weiner 1989). Whereas only a few examples of the formation of sulfide minerals by BCM are known, iron sulfides form in vast quantities by BIM and affect the global cycling of iron, sulfur, oxygen, and carbon (Canfield et al. 2000; Berner 2001).
Organisms are also able to break minerals down. The dissolution of sulfides can be enhanced by biological processes, while some micro-organisms gain their energy by oxidizing the sulfur or the metal in sulfide minerals, thereby converting sulfides into dissolved species or oxides (Kappler and Straub 2005). The biological mediation of both the precipitation and the dissolution of sulfides can be used for practical purposes, such as bioremediation and bioleaching.
Over the past decade, several reviews have been published on biomineralization, many of which include details on sulfides. In the Reviews in Mineralogy & Geochemistry series, three volumes have been devoted to …