gyrobifastigium

plural gyrobifastigia · plural gyrobifastigiums

1. A polyhedral solid formed by joining two face-regular triangular prisms along corresponding square faces, giving a quarter-turn to one prism. It is noted for being one of the few regular polyhedra that packs in three dimensions.

   They observed hard triangular prisms and hard gyrobifastigia to directly transform into their space-filling crystal, while hard truncated octahedra, rhombic.

   2012, Amir Haji Akbari Balou, Thermodynamics of the Hard Tetrahedron System (PhD Dissertation in Chemical Engineering, University of Michigan)

   2 more examples

   To elucidate this complex correlation, we carried out detailed Monte Carlo simulations of six convex space-filling polyhedrons, namely, truncated octahedrons, rhombic dodecahedrons, hexagonal prisms, cubes, gyrobifastigiums and triangular prisms.

   2011 February, Umang Agarwal, Fernando A Escobedo, “Mesophase behaviour of polyhedral particles”, in Nature materials, volume 10

   But there are solids constructed from two or more regular prisms that also pack space. An interesting example (with an equally interesting name) is the gyrobifastigium, constructed from two regular triangular prisms. See Figure 1.2.14 for a picture of a gyrobifastigium, and a pattern (called a net) for constructing one.

   2015, Claudi Alsina, Roger B. Nelsen, A Mathematical Space Odyssey: Solid Geometry in the 21st Century, →ISBN