In geometry, aconvex polyhedron whose faces areregular polygons is known as aJohnson solid, or sometimes as a Johnson–Zalgaller solid.[1] Some authors excludeuniform polyhedra (in whichall vertices are symmetric to each other) from the definition; uniform polyhedra includePlatonic andArchimedean solids as well asprisms andantiprisms.[2]The Johnson solids are named after American mathematicianNorman Johnson (1930–2017), who published a list of 92 non-uniform Johnson polyhedra in 1966. His conjecture that the list was complete and no other examples existed was proven by Russian-Israeli mathematicianVictor Zalgaller (1920–2020) in 1969.[3]
This article lists the 92 non-uniform Johnson solids, accompanied by images. They are listed alongside their basic elements (vertices,edges, andfaces), and their most importantgeneral characteristics, includingsymmetry groups (,,,,,),order,surface area, andvolume; an overview of these follows first, before presenting the complete list of non-uniform Johnson solids.
Every polyhedron has its owncharacteristics, includingsymmetry and measurement. An object is said to have symmetry if there is atransformation that maps it to itself. All of those transformations may be composed in agroup, alongside the group's number ofelements, known as theorder. In two-dimensional space, these transformations includerotating around the center of a polygon andreflecting an object around theperpendicular bisector of a polygon. The mensuration of polyhedra includes thesurface area andvolume. Anarea is a two-dimensional measurement calculated by the product of length and width; for a polyhedron, the surface area is the sum of the areas of all of its faces.[4] A volume is a measurement of a region in three-dimensional space.[5] The volume of a polyhedron may be ascertained in different ways: either through its base and height (like forpyramids andprisms), by slicing it off into pieces and summing their individual volumes, or by finding theroot of apolynomial representing the polyhedron.[6]
A polygon that is rotated symmetrically by is denoted by, acyclic group of order; combining this with the reflection symmetry results in the symmetry ofdihedral group of order.[7] Inthree-dimensional symmetry point groups, the transformations preserving a polyhedron's symmetry include the rotation around the line passing through the base center, known as theaxis of symmetry, and the reflection relative to perpendicular planes passing through the bisector of a base, which is known as thepyramidal symmetry of order. The transformation that preserves a polyhedron's symmetry by reflecting it across a horizontal plane is known as theprismatic symmetry of order. Theantiprismatic symmetry of order preserves the symmetry by rotating its half bottom and reflection across the horizontal plane.[8] The symmetry group of order preserves the symmetry by rotation around the axis of symmetry and reflection on the horizontal plane; the specific case preserving the symmetry by one full rotation is of order 2, often denoted as.[9]
Seventeen Johnson solids may be categorized aselementary polyhedra, meaning they cannot be separated by a plane to create two small convex polyhedra with regular faces. The first six Johnson solids satisfy this criterion: theequilateral square pyramid,pentagonal pyramid,triangular cupola,square cupola,pentagonal cupola, andpentagonal rotunda. The criterion is also satisfied by eleven other Johnson solids, specifically thetridiminished icosahedron,parabidiminished rhombicosidodecahedron,tridiminished rhombicosidodecahedron,snub disphenoid,snub square antiprism,sphenocorona,sphenomegacorona,hebesphenomegacorona,disphenocingulum,bilunabirotunda, andtriangular hebesphenorotunda.[10] The rest of the Johnson solids are not elementary, and they are constructed using the first six Johnson solids together with Platonic and Archimedean solids in various processes.Augmentation involves attaching the Johnson solids onto one or more faces of polyhedra, whileelongation orgyroelongation involve joining them onto the bases of a prism or antiprism, respectively. Some others are constructed bydiminishment, the removal of one of the first six solids from one or more of a polyhedron's faces.[11]
The table below lists the 92 (non-uniform) Johnson solids. The table includes each solid's enumeration (denoted as).[12] It also includes each solid'ssymmetry group and number of vertices, edges, and faces, as well as its surface area and volume when constructed with edge length 1. For simplicity, the table uses the quantity.
| Solid name | Image | Vertices | Edges | Faces | Symmetry group andorder[13] | Surface area, exact[14] | Surface area, approx.[14] | Volume, exact[14] | Volume, approx.[14] | |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Square pyramid | 5 | 8 | 5 | of order 8 | 2.7321 | 0.2357 | |||
| 2 | Pentagonal pyramid | 6 | 10 | 6 | of order 10 | 3.8855 | 0.3015 | |||
| 3 | Triangular cupola | 9 | 15 | 8 | of order 6 | 7.3301 | 1.1785 | |||
| 4 | Square cupola | 12 | 20 | 10 | of order 8 | 11.5605 | 1.9428 | |||
| 5 | Pentagonal cupola | 15 | 25 | 12 | of order 10 | 16.5798 | 2.3241 | |||
| 6 | Pentagonal rotunda | 20 | 35 | 17 | of order 10 | 22.3472 | 6.9178 | |||
| 7 | Elongated triangular pyramid | 7 | 12 | 7 | of order 6 | 4.7321 | 0.5509 | |||
| 8 | Elongated square pyramid | 9 | 16 | 9 | of order 8 | 6.7321 | 1.2357 | |||
| 9 | Elongated pentagonal pyramid | 11 | 20 | 11 | of order 10 | 8.8855 | 2.022 | |||
| 10 | Gyroelongated square pyramid | 9 | 20 | 13 | of order 8 | 6.1962 | 1.1927 | |||
| 11 | Gyroelongated pentagonal pyramid (diminished icosahedron) | 11 | 25 | 16 | of order 10 | 8.2157 | 1.8802 | |||
| 12 | Triangular bipyramid | 5 | 9 | 6 | of order 12 | 2.5981 | 0.2357 | |||
| 13 | Pentagonal bipyramid | 7 | 15 | 10 | of order 20 | 4.3301 | 0.6030 | |||
| 14 | Elongated triangular bipyramid | 8 | 15 | 9 | of order 12 | 5.5981 | 0.6687 | |||
| 15 | Elongated square bipyramid | 10 | 20 | 12 | of order 16 | 7.4641 | 1.4714 | |||
| 16 | Elongated pentagonal bipyramid | 12 | 25 | 15 | of order 20 | 9.3301 | 2.3235 | |||
| 17 | Gyroelongated square bipyramid | 10 | 24 | 16 | of order 16 | 6.9282 | 1.4284 | |||
| 18 | Elongated triangular cupola | 15 | 27 | 14 | of order 6 | 13.3301 | 3.7766 | |||
| 19 | Elongated square cupola | 20 | 36 | 18 | of order 8 | 19.5605 | 6.7712 | |||
| 20 | Elongated pentagonal cupola | 25 | 45 | 22 | of order 10 | 26.5798 | 10.0183 | |||
| 21 | Elongated pentagonal rotunda | 30 | 55 | 27 | of order 10 | 32.3472 | 14.612 | |||
| 22 | Gyroelongated triangular cupola | 15 | 33 | 20 | of order 6 | 12.5263 | 3.5161 | |||
| 23 | Gyroelongated square cupola | 20 | 44 | 26 | of order 8 | 18.4887 | 6.2108 | |||
| 24 | Gyroelongated pentagonal cupola | 25 | 55 | 32 | of order 10 | 25.2400 | 9.0733 | |||
| 25 | Gyroelongated pentagonal rotunda | 30 | 65 | 37 | of order 10 | 31.0075 | 13.6671 | |||
| 26 | Gyrobifastigium | 8 | 14 | 8 | of order 8 | 5.7321 | 0.8660 | |||
| 27 | Triangular orthobicupola | 12 | 24 | 14 | of order 12 | 9.4641 | 2.3570 | |||
| 28 | Square orthobicupola | 16 | 32 | 18 | of order 16 | 13.4641 | 3.8856 | |||
| 29 | Square gyrobicupola | 16 | 32 | 18 | of order 16 | |||||
| 30 | Pentagonal orthobicupola | 20 | 40 | 22 | of order 20 | 17.7711 | 4.6481 | |||
| 31 | Pentagonal gyrobicupola | 20 | 40 | 22 | of order 20 | |||||
| 32 | Pentagonal orthocupolarotunda | 25 | 50 | 27 | of order 10 | 23.5385 | 9.2418 | |||
| 33 | Pentagonal gyrocupolarotunda | 25 | 50 | 27 | of order 10 | 23.5385 | ||||
| 34 | Pentagonal orthobirotunda | 30 | 60 | 32 | of order 20 | 29.306 | 13.8355 | |||
| 35 | Elongated triangular orthobicupola | 18 | 36 | 20 | of order 12 | 15.4641 | 4.9551 | |||
| 36 | Elongated triangular gyrobicupola | 18 | 36 | 20 | of order 12 | |||||
| 37 | Elongated square gyrobicupola | 24 | 48 | 26 | of order 16 | 21.4641 | 8.714 | |||
| 38 | Elongated pentagonal orthobicupola | 30 | 60 | 32 | of order 20 | 27.7711 | 12.3423 | |||
| 39 | Elongated pentagonal gyrobicupola | 30 | 60 | 32 | of order 20 | |||||
| 40 | Elongated pentagonal orthocupolarotunda | 35 | 70 | 37 | of order 10 | 33.5385 | 16.936 | |||
| 41 | Elongated pentagonal gyrocupolarotunda | 35 | 70 | 37 | of order 10 | |||||
| 42 | Elongated pentagonal orthobirotunda | 40 | 80 | 42 | of order 20 | 39.306 | 21.5297 | |||
| 43 | Elongated pentagonal gyrobirotunda | 40 | 80 | 42 | of order 20 | |||||
| 44 | Gyroelongated triangular bicupola | 18 | 42 | 26 | of order 6 | 14.6603 | 4.6946 | |||
| 45 | Gyroelongated square bicupola | 24 | 56 | 34 | of order 8 | 20.3923 | 8.1536 | |||
| 46 | Gyroelongated pentagonal bicupola | 30 | 70 | 42 | of order 10 | 26.4313 | 11.3974 | |||
| 47 | Gyroelongated pentagonal cupolarotunda | 35 | 80 | 47 | of order 5 | 32.1988 | 15.9911 | |||
| 48 | Gyroelongated pentagonal birotunda | 40 | 90 | 52 | of order 10 | 37.9662 | 20.5848 | |||
| 49 | Augmented triangular prism | 7 | 13 | 8 | of order 4 | 4.5981 | 0.6687 | |||
| 50 | Biaugmented triangular prism | 8 | 17 | 11 | of order 4 | 5.3301 | 0.9044 | |||
| 51 | Triaugmented triangular prism | 9 | 21 | 14 | of order 12 | 6.0622 | 1.1401 | |||
| 52 | Augmented pentagonal prism | 11 | 19 | 10 | of order 4 | 9.173 | 1.9562 | |||
| 53 | Biaugmented pentagonal prism | 12 | 23 | 13 | of order 4 | 9.9051 | 2.1919 | |||
| 54 | Augmented hexagonal prism | 13 | 22 | 11 | of order 4 | 11.9282 | 2.8338 | |||
| 55 | Parabiaugmented hexagonal prism | 14 | 26 | 14 | of order 8 | 12.6603 | 3.0695 | |||
| 56 | Metabiaugmented hexagonal prism | 14 | 26 | 14 | of order 4 | |||||
| 57 | Triaugmented hexagonal prism | 15 | 30 | 17 | of order 12 | 13.3923 | 3.3052 | |||
| 58 | Augmented dodecahedron | 21 | 35 | 16 | of order 10 | 21.0903 | 7.9646 | |||
| 59 | Parabiaugmented dodecahedron | 22 | 40 | 20 | of order 20 | 21.5349 | 8.2661 | |||
| 60 | Metabiaugmented dodecahedron | 22 | 40 | 20 | of order 4 | |||||
| 61 | Triaugmented dodecahedron | 23 | 45 | 24 | of order 6 | 21.9795 | 8.5676 | |||
| 62 | Metabidiminished icosahedron | 10 | 20 | 12 | of order 4 | 7.7711 | 1.5787 | |||
| 63 | Tridiminished icosahedron | 9 | 15 | 8 | of order 6 | 7.3265 | 1.2772 | |||
| 64 | Augmented tridiminished icosahedron | 10 | 18 | 10 | of order 6 | 8.1925 | 1.3950 | |||
| 65 | Augmented truncated tetrahedron | 15 | 27 | 14 | of order 6 | 14.2583 | 3.8891 | |||
| 66 | Augmented truncated cube | 28 | 48 | 22 | of order 8 | 34.3383 | 15.5425 | |||
| 67 | Biaugmented truncated cube | 32 | 60 | 30 | of order 16 | 36.2419 | 17.4853 | |||
| 68 | Augmented truncated dodecahedron | 65 | 105 | 42 | of order 10 | 102.1821 | 87.3637 | |||
| 69 | Parabiaugmented truncated dodecahedron | 70 | 120 | 52 | of order 20 | 103.3734 | 89.6878 | |||
| 70 | Metabiaugmented truncated dodecahedron | 70 | 120 | 52 | of order 4 | |||||
| 71 | Triaugmented truncated dodecahedron | 75 | 135 | 62 | of order 6 | 104.5648 | 92.0118 | |||
| 72 | Gyrate rhombicosidodecahedron | 60 | 120 | 62 | of order 10 | 59.306 | 41.6153 | |||
| 73 | Parabigyrate rhombicosidodecahedron | 60 | 120 | 62 | of order 20 | |||||
| 74 | Metabigyrate rhombicosidodecahedron | 60 | 120 | 62 | of order 4 | |||||
| 75 | Trigyrate rhombicosidodecahedron | 60 | 120 | 62 | of order 6 | |||||
| 76 | Diminished rhombicosidodecahedron | 55 | 105 | 52 | of order 10 | 58.1147 | 39.2913 | |||
| 77 | Paragyrate diminished rhombicosidodecahedron | 55 | 105 | 52 | of order 10 | |||||
| 78 | Metagyrate diminished rhombicosidodecahedron | 55 | 105 | 52 | of order 2 | |||||
| 79 | Bigyrate diminished rhombicosidodecahedron | 55 | 105 | 52 | of order 2 | |||||
| 80 | Parabidiminished rhombicosidodecahedron | 50 | 90 | 42 | of order 20 | 56.9233 | 36.9672 | |||
| 81 | Metabidiminished rhombicosidodecahedron | 50 | 90 | 42 | of order 4 | |||||
| 82 | Gyrate bidiminished rhombicosidodecahedron | 50 | 90 | 42 | of order 2 | |||||
| 83 | Tridiminished rhombicosidodecahedron | 45 | 75 | 32 | of order 6 | 55.732 | 34.6432 | |||
| 84 | Snub disphenoid | 8 | 18 | 12 | of order 8 | 5.1962 | 0.8595 | |||
| 85 | Snub square antiprism | 16 | 40 | 26 | of order 16 | 12.3923 | 3.6012 | |||
| 86 | Sphenocorona | 10 | 22 | 14 | of order 4 | 7.1962 | 1.5154 | |||
| 87 | Augmented sphenocorona | 11 | 26 | 17 | of order 2 | 7.9282 | 1.7511 | |||
| 88 | Sphenomegacorona | 12 | 28 | 18 | of order 4 | 8.9282 | 1.9481 | |||
| 89 | Hebesphenomegacorona | 14 | 33 | 21 | of order 4 | 10.7942 | 2.9129 | |||
| 90 | Disphenocingulum | 16 | 38 | 24 | of order 8 | 12.6603 | 3.7776 | |||
| 91 | Bilunabirotunda | 14 | 26 | 14 | of order 8 | 12.346 | 3.0937 | |||
| 92 | Triangular hebesphenorotunda | 18 | 36 | 20 | of order 6 | 16.3887 | 5.1087 |