Rhombic dodecahedral honeycomb

Summary

Rhombic dodecahedral honeycomb
Rhombic dodecahedra.png
Type convex uniform honeycomb dual
Coxeter-Dynkin diagram CDel node fh.pngCDel 4.pngCDel node.pngCDel 3.pngCDel node.pngCDel 4.pngCDel node.png = CDel node f1.pngCDel 3.pngCDel node.pngCDel split1-43.pngCDel nodes.png
CDel node f1.pngCDel split1.pngCDel nodes.pngCDel split2.pngCDel node.png
Cell type Dodecahedrille cell.png
Rhombic dodecahedron V3.4.3.4
Face types Rhombus
Space group Fm3m (225)
Coxeter notation ½, [1+,4,3,4]
, [4,31,1]
×2, <[3[4]]>
Dual tetrahedral-octahedral honeycomb
Properties edge-transitive, face-transitive, cell-transitive

The rhombic dodecahedral honeycomb (also dodecahedrille) is a space-filling tessellation (or honeycomb) in Euclidean 3-space. It is the Voronoi diagram of the face-centered cubic sphere-packing, which has the densest possible packing of equal spheres in ordinary space (see Kepler conjecture).

GeometryEdit

It consists of copies of a single cell, the rhombic dodecahedron. All faces are rhombi, with diagonals in the ratio 1:2. Three cells meet at each edge. The honeycomb is thus cell-transitive, face-transitive, and edge-transitive; but it is not vertex-transitive, as it has two kinds of vertex. The vertices with the obtuse rhombic face angles have 4 cells. The vertices with the acute rhombic face angles have 6 cells.

The rhombic dodecahedron can be twisted on one of its hexagonal cross-sections to form a trapezo-rhombic dodecahedron, which is the cell of a somewhat similar tessellation, the Voronoi diagram of hexagonal close-packing.

   
The honeycomb can be derived from an alternate cube tessellation by augmenting each face of each cube with a pyramid.
 
The view from inside the rhombic dodecahedral honeycomb.

ColoringsEdit

Cells can be given 4 colors in square layers of 2-colors where neighboring faces have different colors, and 6 colors in hexagonal layers of 3 colors where same-colored cells have no contact at all.

4-colors 6-colors
   
Alternate square layers yellow, blue with red and green Alternate hexagonal layers of red,green,blue and magenta, yellow, cyan.

Related honeycombsEdit

The rhombic dodecahedral honeycomb can be dissected into a trigonal trapezohedral honeycomb with each rhombic dodecahedron dissected into 4 trigonal trapezohedrons. Each rhombic dodecahedra can also be dissected with a center point into 12 rhombic pyramids of the rhombic pyramidal honeycomb.

Trapezo-rhombic dodecahedral honeycombEdit

Trapezo-rhombic dodecahedral honeycomb
 
Type convex uniform honeycomb dual
Cell type trapezo-rhombic dodecahedron VG3.4.3.4
 
Face types rhombus,
trapezoid
Symmetry group P63/mmc
Dual gyrated tetrahedral-octahedral honeycomb
Properties edge-uniform, face-uniform, cell-uniform

The trapezo-rhombic dodecahedral honeycomb is a space-filling tessellation (or honeycomb) in Euclidean 3-space. It consists of copies of a single cell, the trapezo-rhombic dodecahedron. It is similar to the higher symmetric rhombic dodecahedral honeycomb which has all 12 faces as rhombi.

 

Related honeycombsEdit

It is a dual to the vertex-transitive gyrated tetrahedral-octahedral honeycomb.

 

Rhombic pyramidal honeycombEdit

Rhombic pyramidal honeycomb
(No image)
Type Dual uniform honeycomb
Coxeter-Dynkin diagrams      
       
Cell  
rhombic pyramid
Faces Rhombus
Triangle
Coxeter groups [4,31,1],  
[3[4]],  
Symmetry group Fm3m (225)
vertex figures    
     ,      ,      
Dual Cantic cubic honeycomb
Properties Cell-transitive

The rhombic pyramidal honeycomb or half oblate octahedrille is a uniform space-filling tessellation (or honeycomb) in Euclidean 3-space.

This honeycomb can be seen as a rhombic dodecahedral honeycomb, with the rhombic dodecahedra dissected with its center into 12 rhombic pyramids.

 
rhombic dodecahedral honeycomb
 
Rhombohedral dissection
 
Within a cube

Related honeycombsEdit

It is dual to the cantic cubic honeycomb:

 

See alsoEdit

ReferencesEdit

  • Williams, Robert (1979). The Geometrical Foundation of Natural Structure: A Source Book of Design. Dover Publications, Inc. p. 168. ISBN 0-486-23729-X.

External linksEdit