Mössbauer study of natural iron-oxide complexes

Abstract

Typical Fe-oxide complex assemblage in rock samples taken from Lake Victoria Goldfield in Tanzania was studied using Mössbauer spectroscopy between room temperature and 4.2 K. The room temperature Mössbauer spectrum of a typical rock sample from the region is a mixture of two-line patterns and a six-line pattern. At 200 K the two-line pattern starts to develop into a rather asymmetric, broad width six-line pattern which at 4.2 K has hyperfine field, B₈₂, of about 50 T, δ = -0.20 mm/s and δ= 0.24 mm/s. The analysis of the ⁵⁷Fe-Mössbauer spectra shows that the rock sample is composed of hexagonal pyrrhotite, amphibole silicate and α-FeOOH. Details of the characterisation of the phases of the Fe-oxide complex, α-FeOOH is the basis of the report.