Professor YANG Zhuming and his team study the crystal structure of nanlingite. They find that nanlingite is the first mineral with a [Fe(AsO₃)₆] configuration.

The structure was solved and refined on single-crystal X-ray data. The complex framework is formed by edge- and corner-sharing of distorted NaF₈ and CaF₄O₄ cubes, MgF₂O₄ octahedra, and AsO₃ trigonal pyramids. This [Fe(AsO₃)₆] cluster is a novel configuration in the crystal chemistry of minerals. The chemical formula of nanlingite is Na(Ca, Li, Na)₆(Mg, Fe)₁₂(AsO₃)₂[Fe(AsO₃)₆] F₁₄ with Z=3 according to the crystal structure refinement.

Yang et al. Crystal structure of nanlingite – the first mineral with a [Fe(AsO₃)₆] configuration. European Journal of Mineralogy. 2011，23: 63-71 (Download Here)

Fig. Perspective view of the nanlingite structure. The red octahedral are occupied by Fe. The yellow distorted cubes illustrate NaF₈. The light and dark blue octahedra are occupied by Mg. The Ca atoms are shown as small green spheres. As-O bonds are given in yellow. (Image by YANG)