Summary: Goethites of well-crystallized appearance from a sedimentary ore deposit have been studied by Mössbauer spectroscopy and other methods following HCl corrosion, particle size fractionation, and annealing treatments.

The goethites contained an appreciable amount of Si, but were not significantly Al-substituted. The observed broad and asymmetric resonant lines of the Mössbauer spectra are considered to result from this Si which, interspersed in the goethite structure, would interrupt magnetic coupling and give rise to a reduced and inhomogeneous magnetic hyperfine field.