page_title: Regular icosahedron
section_title: Uses and natural forms
hierarchical_section_title: Regular icosahedron / Uses and natural forms
caption_attribution_description: English: Electron microscope image (STEM-HAADF) of a gold nanoparticle showing 5-fold twinning. Microscope: Jeol, 200 kV, 3rd-order aberration corrected (illumination beam only).
context_page_description: In geometry, a regular icosahedron is a convex polyhedron with 20 faces, 30 edges and 12 vertices. It is one of the five Platonic solids, and the one with the most sides.
  It has five equilateral triangular faces meeting at each vertex. It is represented by its Schläfli symbol {3,5}, or sometimes by its vertex figure as 3.3.3.3.3 or 3⁵. It is the dual of the dodecahedron, which is represented by {5,3}, having three pentagonal faces around each vertex.
  A regular icosahedron is a strictly convex deltahedron and a gyroelongated pentagonal bipyramid and a biaugmented pentagonal antiprism in any of six orientations.
  The name comes from Greek εἴκοσι, meaning 'twenty', and ἕδρα, meaning 'seat'. The plural can be either "icosahedrons" or "icosahedra".
caption: Gold nanoparticle viewed by transmission electron microscopy.
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