Skip to main content
Fig. 8 | Geochemical Transactions

Fig. 8

From: Fe(II) reduction of pyrolusite (β-MnO2) and secondary mineral evolution

Fig. 8

57Fe Mössbauer spectra of all experimental data collected in which only the final resuspension of Mn particles was done using 57Fe(II). Room temperature (RT, 298 K) spectra are provided for all experiments (left column), with selected 77 K spectra of identical experiments (right column) for comparison. After only one resuspension in 3 mM Fe(II), the resulting spectrum is devoid of multi-sextet character typical of magnetite. As the amount of Fe(II) exposure increases, we can see the final deposition of 57Fe atoms onto the particle surface results in an increasingly large multi-sextet signal and a gradual disappearance of the doublet associated with lepidocrocite formation. Comparing RT spectra with 77 K, magnetite sextets appear to overlap more thoroughly at 77 K, which is commonly observed below the Verwey transition temperature (~ 120 K). Spectra collected at 77 K also contain a visibly higher ratio of sextet: doublet spectral area, possibly indicating the presence of unordered magnetite at room temperature, which orders into a typical sextet at lower collection temperatures

Back to article page
\