Hyperfine structures of iron(II) sulphates: Melanterite and rozenite

Moessbauer spectra of melanterite display two different iron environments. The difference in the quadrupole splittings comes from both the lattice and valence contributions. The lattice contributions for the two ferrous sites are of equal magnitude but of opposite signs while the valence contributions are both positive. Spectra of rozenite reveal only one ferrous site; a sample obtained from incomplete transformation of melanterite into rozenite shows that the low temperature quadrupole splitting of ferrous ions could be as high as 4 mm/s. (orig.)