Stereohedron

In geometry and crystallography, a stereohedron is a convex polyhedron that fills space isohedrally, meaning that the symmetries of the tiling take any copy of the stereohedron to any other copy.

Two-dimensional analogues to the stereohedra are called planigons. Higher dimensional polytopes can also be stereohedra, while they would more accurately be called stereotopes.

Plesiohedra

A subset of stereohedra are called plesiohedrons, defined as the Voronoi cells of a symmetric Delone set.

Parallelohedrons are plesiohedra which are space-filling by translation only. Edges here are colored as parallel vectors.

Parallelohedra
cube hexagonal prism rhombic dodecahedron elongated dodecahedron truncated octahedron

Other periodic stereohedra

The catoptric tessellation contain stereohedra cells. Dihedral angles are integer divisors of 180°, and are colored by their order. The first three are the fundamental domains of C~3, B~3, and A~3 symmetry, represented by Coxeter-Dynkin diagrams: , and . B~3 is a half symmetry of C~3, and A~3 is a quarter symmetry.

Any space-filling stereohedra with symmetry elements can be dissected into smaller identical cells which are also stereohedra. The name modifiers below, half, quarter, and eighth represent such dissections.

Catoptric cells
Faces 456812
Type Tetrahedra Square pyramid Triangular bipyramid Cube Octahedron Rhombic dodecahedron
Images
1/48 (1)

1/24 (2)

1/12 (4)

1/12 (4)

1/24 (2)

1/6 (8)

1/6 (8)

1/12 (4)

1/4 (12)

1 (48)

1/2 (24)

1/3 (16)

2 (96)
Symmetry
(order)
C1
1
C1v
2
D2d
4
C1v
2
C1v
2
C4v
8
C2v
4
C2v
4
C3v
6
Oh
48
D3d
12
D4h
16
Oh
48
Honeycomb Eighth pyramidille
Triangular pyramidille
Oblate tetrahedrille
Half pyramidille
Square quarter pyramidille
Pyramidille
Half oblate octahedrille
Quarter oblate octahedrille
Quarter cubille
Cubille
Oblate cubille
Oblate octahedrille
Dodecahedrille

Other convex polyhedra that are stereohedra but not parallelohedra nor plesiohedra include the gyrobifastigium.

Others
Faces 81012
Symmetry
(order)
D2d (8) D4h (16)
Images
Cell Gyrobifastigium Elongated
gyrobifastigium
Ten of diamonds Elongated
square bipyramid

References

  1. ↑ Lekkerkerker, C. G.; Gruber, Pascale (1987). Geometry of Numbers. North-Holland. p. 166. ISBN 978-0-08-096023-4.