Аннотация:To develop their previous results, the authors demonstrated that the structural-type phases Th2Ni17and Th2Zn17may be represented as the densest helical packing of tetrablock chains as linear 7-vertex unions of four tetrahedrons over faces. It was concluded that the tetrablock can be used as a universal building unit, including more complex structural types of Frank–Kasper phases than those considered in our previous works.