Comparative Study of Siderites of Hydrothermal, Sedimentary, and Bacterial Origin by Physical Methods

The physicochemical properties of siderites (FeCO3) of different origin have attracted attention due to challenges in the diagnostics with the aim of evaluating the involvement of bacteria in the formation of iron-rich sedimentary deposits. A comparative study of siderites of chemical and bacterial origin was performed by Mossbauer spectroscopy, X-ray diffraction, and scanning electron microscopy for the purpose of determining the possible characteristics, which will allow the identification of biogenic siderite. It was found that all the characterized siderites have significant differences in the crystal morphology associated with the physicochemical conditions of their formation. Siderites of bacterial origin are characterized by a smaller crystal size compared to siderites of hydrothermal or sedimentary origin. The inhomogeneity of the nearest environment of the iron atoms, which was found for siderites of bacterial origin and which is manifested in the Mossbauer spectra as a larger width of the quadrupole shift distribution, can be used as a diagnostic indication of biogenic siderites.

Automated summary

This study compared siderites of chemical and bacterial origin using Mossbauer spectroscopy, X-ray diffraction, and scanning electron microscopy. It found significant differences in crystal morphology and the physicochemical conditions of their formation, suggesting a potential diagnostic indication of biogenic siderites.