Stereohedron
Convex polyhedron that fills space isohedrally
From Wikipedia, the free encyclopedia
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.[1]
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.
| 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 , , and symmetry, represented by Coxeter-Dynkin diagrams: ![]()
![]()
![]()
![]()
![]()
![]()
, ![]()
![]()
![]()
![]()
and ![]()
![]()
. is a half symmetry of , and 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.
| Faces | 4 | 5 | 6 | 8 | 12 | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 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.
| Faces | 8 | 10 | 12 | |
|---|---|---|---|---|
| Symmetry (order) |
D2d (8) | D4h (16) | ||
| Images | ||||
| Cell | Gyrobifastigium | Elongated gyrobifastigium |
Ten of diamonds | Elongated square bipyramid |