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Electric and Magnetic Properties of Biological Materials
Published in Ben Greenebaum, Frank Barnes, Bioengineering and Biophysical Aspects of Electromagnetic Fields, 2018
Camelia Gabriel, Azadeh Peyman
Although magnetite and ferrihydrite are two of the most ubiquitous magnetic materials in organisms, they are not the only ones. Greigite (Fe7S8) is a ferrimagnetic iron sulfide found in some iron-reducing bacteria (Posfai et al. 1998). It has a strong magnetic moment similar to magnetite and is thought to be produced as a by-product of iron reduction. Hematite (Fe2O3) and wüstite-like (FeO) iron phases also have recently been found within human ferritin (Quintana et al. 2004). And hemosiderin (FeOOH) is a goethite-like iron oxyhydroxide that is anti-ferromagnetic and is found primarily in pathogenic liver tissue (St. Pierre et al. 1998).
Depositional rate, grain size and magnetic mineral sulfidization in turbidite sequences, Hikurangi Margin, New Zealand
Published in New Zealand Journal of Geology and Geophysics, 2022
Atsushi Noda, Annika Greve, Adam Woodhouse, Martin Crundwell
The original purpose of this study was to reveal the sediment provenance of turbidites in the Hikurangi Trough based on their environmental magnetic properties. However, as we proceeded with our analysis, we realised that the original information was significantly modified by authigenesis, in particular the reduction of the original remanence carriers to the greigite (Fe3S4). Greigite is a strongly ferrimagnetic iron sulfide mineral and is an intermediate mineral phase in a progressive reduction chain from magnetite (Fe3O4) to pyrite (FeS2) (Roberts 2015; Greve et al. 2021). This kind of alteration is common in marine sediments exposed to organo-clastic sulfate reduction (degradation of organic materials or anaerobic oxidation of methane, AOM) in the sulfate–methane transition zone (SMTZ) where hydrogen sulfide (H2S or HS−1) forms iron sulfides (e.g. Roberts 2015). This paper documents the diagenetic characteristics of the detrital magnetic minerals preserved in these turbidites (trench-wedge deposits) and explores relationships between sedimentary features of turbidites (grain size, bed thickness, frequency, and so on) and diagenetic processes that occur during and following turbidite deposition.
Magnetic sorbents biomineralization on the basis of iron sulphides
Published in Environmental Technology, 2018
Jana Jencarova, Alena Luptakova, Nikola Vitkovska, Dalibor Matysek, Petr Jandacka
We performed magnetic measurements to revise the results of XRD (see Figure 4). These measurements confirmed the presence of magnetic minerals in biogenic samples. One can see that amount of greigite in samples correlates with magnetic susceptibility and magnetization. All samples created in process of biologically induced mineralization have magnetic hysteresis that is induced by ferrimagnetic crystals of greigite and by uncompensated spins on the surface of other crystals.