Geomicrobiology of Iron
Iron is the fourth most abundant element in the Earth’s crust and the most abundant element in the Earth as a whole. Its average concentration in the crust has been estimated to be approximately 5.0% (Rankama and Sahama, 1950). It is found in a number of minerals in rocks, soil, and sediments. Table 17.1 lists minerals in which iron is a major structural component.