Lonsdaleite, a Hexagonal Polymorph of Diamond

  title={Lonsdaleite, a Hexagonal Polymorph of Diamond},
  author={Clifford Frondel and Ursula B. Marvin},
TWO well known atomic arrangements found among tetrahedrally co-ordinated AX compounds such as silicon carbide (SiC) and zinc sulphide (ZnS) are those based on a cubic close-packed array or on a hexagonal close-packed array of tetrahedra. The two polymorphs are generally designated as the sphalerite and wurtzite types, respectively, from their occurrence in zinc sulphide. The crystal structures of the Group IV elements, carbon, silicon, germanium and α-tin, are based on the cubic close-packed… 
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