International
Tables for
Crystallography
Volume A
Space-group symmetry
Edited by M. I. Aroyo

International Tables for Crystallography (2016). Vol. A, ch. 3.2, pp. 742-744

## Table 3.2.3.1

H. Klapper,a Th. Hahna and M. I. Aroyoc
 Table 3.2.3.1| top | pdf | The ten two-dimensional crystallographic point groups
 The point groups are listed in blocks according to crystal system and are specified by their Hermann–Mauguin symbols. For each point group, the stereographic projections show (on the left) the general position and (on the right) the symmetry elements. The list of Wyckoff positions includes: Columns 1 to 4: multiplicity, Wyckoff letter, oriented site-symmetry symbol, coordinate doublets; Under the stereographic projections: edge forms (in roman type) and point forms (in italics); if there are two entries, the second entry refers to a limiting (noncharacteristic) form; Last column: Miller indices of equivalent edges [for hexagonal groups, Bravais–Miller indices (hki) are used].
 OBLIQUE SYSTEM 1 1 a 1 Single edge (hk) Single point 2 2 a 1 Pair of parallel edges Line segment through origin 1 o 2 0, 0 Point in origin RECTANGULAR SYSTEM m 2 b 1 Pair of edges Line segment Pair of parallel edges Line segment through origin 1 a .m. Single edge (01) or Single point 2mm 4 c 1 Rhomb Rectangle 2 b .m. Pair of parallel edges Line segment through origin 2 a ..m Pair of parallel edges Line segment through origin 1 o 2mm Point in origin SQUARE SYSTEM 4 4 a 1 Square Square 1 o 4.. Point in origin 4mm 8 c 1 Ditetragon Truncated square 4 b ..m Square Square 4 a .m. Square Square 1 o 4mm Point in origin HEXAGONAL SYSTEM 3 3 a 1 Trigon Trigon 1 o 3.. Point in origin 3m1 6 b 1 Ditrigon Truncated trigon Hexagon Hexagon 3 a .m. Trigon Trigon or 1 o 3m. Point in origin 31m 6 b 1 Ditrigon Truncated trigon Hexagon Hexagon 3 a ..m Trigon Trigon or 1 o 3.m Point in origin 6 6 a 1 Hexagon Hexagon 1 o 6.. Point in origin 6mm 12 c 1 Dihexagon Truncated hexagon 6 b .m. Hexagon Hexagon 6 a ..m Hexagon Hexagon 1 o 6mm Point in origin