The crystal structure of brunogeierite, Fe2GeO4 spinel

Brunogeierite, Fe2GeO4, a = 8.4127(7) Angstrom, V = 595.4(1) Angstrom (3), is a rare germanate spinel from Tsumeb, Namibia. Its structure has been ref ined to an R index of 2.2%. The oxygen parameter, u, is 0.2466(1), indicati ng nearly ideal cubic close-packing of oxygen atoms. There is exact agreeme nt between the observed a unit-cell dimension and that calculated from the observed Ge-O and Fe-O bond lengths. The cations Ge and Fe are fully ordere d at tetrahedral (A) and octahedral (B) sites, respectively, in keeping wit h synthetic germanate spinels, all of which are fully-ordered normal spinel s.