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Ferrihydrite is an iron oxyhydroxide with nominal formula 5Fe2O3·9H2O. Although it is an accepted mineral there is much controversy about its crystal structure and crystal chemistry. It forms by rapid precipitation when reduced-iron-bearing ground water (or hydrothermal water) encounters oxygenated water. Image File history File links Broom_icon. ... A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure and specific physical properties. ... Enargite crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ...
The iron oxyhydroxide core of the ferritinprotein is a biotic form of ferrihydrite. Most iron in biota, from bacteria to humans, is stored in this form. Ferritin is a globular protein found mainly in the liver, which can store about 4500 iron (Fe3+)ions in a hollow protein shell made of 24 subunits. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ...
Ferrihydrite is a common mining waste product resulting from iron removal in producing zinc and copper, for example. It is also produced in heavy metal removal technologies for purifying water.
Ferrihydrite is believed to be the main near-surface diagenetic iron oxyhydroxide in aquatic sediments however this is disputed.[1] It is also believed to form biotically on the cell walls of bacteria in aquatic environments however this is also disputed.[2]
References
^ C. van der Zee, D. Roberts, D.G. Rancourt, C.P. Slomp. Nanogoethite is the dominant reactive oxyhydroxide phase in lake and marine sediments. Geology 31 (2003) 993-996.
^ D.G. Rancourt, P.-J. Thibault, D. Mavrocordatos, G. Lamarche. Hydrous ferric oxide precipitation in the presence of nonmetabolizing bacteria: Constraints on the mechanism of a biotic effect. Geochimica et Cosmochimica Acta 69 (2005) 553-577.
Four ferrihydrite suspensions were aged at pH 12 and 50 °C with or without Ba in 0.01 M KN03 for 68 h or in 0.17 M KN03 for 3424 h.
Two ferrihydrite suspensions were aged with and without Sr at pH 8 in 0.1 M KN03 at 70°C. Barium or Sr sorption, or resorption, was measured by periodically centrifuging suspension subsamples, filtering, and analyzing the filtrate for Ba or Sr.
The percent transformation of ferrihydrite to goethite/hematite was estimated from the ratio of oxalate and HC1 extractable Fe.
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