From teaching experience. VIII. Grid ornaments

Abstract

After 7 symmetry groups of borders, 17 symmetry groups of grid ornaments are the next step on the way to 230 space symmetry groups in the university course of crystallography. A simple derivation of grid ornaments is proposed, combining the search for 10 flat clusters and their translations in 5 parallelogram grids. Analysis of grid ornaments in the urban landscape (artistic mosaics, wall claddings, floorings, etc.) draws students to the actual problem of the prevalence of 230 space symmetry groups in minerals.