Zektzerite Structure
Steven Dutch, Professor Emeritus, Natural and Applied Sciences,
Zektzerite (repeating unit) LiNa(Zr,Ti,Hf)Si6O15 is a real grab bag. Pegmatites typically are enriched in oddball elements that don't fit in normal minerals: large cations, tiny cations like Li or Be, and large charge cations like Zr or Sn. This mineral crams them all into one package. Compositionally it resembles the rare silicate brannockite. It has an unusual structure with sinuous double chains of silica tetrahedra.
Above: View of the zigzag silica chains of zektzerite.
Above: oblique view showing the doubling of the chains.
Above: view showing silica chains and linking alkali metal coordination polyhedra. Silicon is purple, Na is yellow, Li is gold and Sn is blue-gray.
Above: end-on view of the structure.
Above: simplified view of the brannockite structure. Zektzerite has a lot of similarities with branncokite. In fact, its structure can be derived from brannockite.
Above: the brannockite structure split into strips.
Above: Shift alternate strips and link tetrahedra.
Above: distort the structure somewhat to bring the inward-pointing tetrahedra together to link up. The sodium atoms fit into the large comma-shaped voids.
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Created 22 April 2013, Last Update
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