Pb₂Fe₂Ge₂O₉, the Germanate Analogue of the Silicate Mineral Melanotekite

The structure of dilead(II) diiron(III) digermanium(IV) oxide, with a minor (2Fe/Mg+Ge) substitution due to growth conditions, has been determined using flux-grown single crystals. Interesting features of the structure include an unsymmetrical splitting of the Pb site and a strong anisotropy of the bridging oxygen atom of the Ge₂O₇ group, both of which also occur in the structure of the silicate mineral melanotekite, Pb₂Fe₂Si₂O₉. These structural features can be associated with the stereoactivity of the Pb²⁺ lone pairs, which is found to be less pronounced in the germanate than in the silicate structure.

-1