Wurtzite 1: introduction

To go directly to the unit cell structure, click the link to page 3 below.

Wurtzite is made of zinc sulfide, though iron(II) is often found in some of the zinc positions, as is also often the case with sphalerite. It is the hexagonal polymorph of the cubic zinc blende. (There is also a third polymorph called matraite which has a trigonal unit cell.) Wurtzite is less common than zinc blende and has a duller lustre (remember that zinc blende's structure is closely related to diamond's). Because hexagonal unit cells are less symmetrical than cubic ones wurtzite crystals manifest themselves in less regular shapes than those of sphalerite, exhibiting a property known as hemimorphism, where the top and bottom of the crystal are different shapes. Sometimes a hexagonal outline can be seen.

A fragment of the bulk structure of wurtzite is shown to the left. The sulfide ions are blue and the zincs are grey.

In the structure on the left the relative size of the ions is to scale, and nearest neighbour ions are virtually in contact. In future pages the ions will not be shown in contact as it obscures the internal structure of the lattice. Rather, they will be scaled to half their atomic radius, ie one eighth of their volume. In any case, the determination of ion size has its problems. What x-ray diffraction determines most accurately are the positions of the nuclei in the lattice.

Go to page 2 to look at the structure in a different representation.

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