Tessellation of the hp lattice

Assuming the mica two-dimensional lattice in the (001) plane is hp [ray = 0], the lattice can be described through a regular tessellation 3,6, i.e. an assemblage of equal 

Number of reflections in the c repeat along reciprocal lattice rows corresponding to family reflections 

Mixed-rotation Series 0 Class a untwinned polytype 

Subfamily A Series 0 orthogonal polytype untwinned or 120°-twinned 

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The geometrical characteristics of the reciprocal lattice rows parallel to c, each taken as a whole, are termed "row features". In the Trigonal model all mica polytypes have the same row features, described by the regular tessellation 3,6 (Takeda and Donnay 1965 see the section Tessellation of the hp lattice ), and the nine R, were classified into three types (Fig. 16) ... 

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