The one exception is the exciting accidental discovery of a 4.22-carat, gem-quality octahedron in Dale County, Alabama.
The exception is an octahedron from another Peruvian mine, Quiruvilca (400 kilometers north of Huanzala).
Earth was a cube, air an octahedron , fire a tetrahedron and water an icosahedron.
Water was an icosahedron, and air had to be an octahedron .
It involves placing the knot inside a plastic octahedron and mapping where the strands of the knot meet.
Theaetetus was the first to study the octahedron and the icosahedron and it is believed that Book XIII of Euclid's Elements is based on his work.
A dodecahedron modified by the octahedron and cube from Nordmark, Sweden, is figured in Goldschmidt.
Finally, the octahedron inscribed in the Venus-orbit sphere has itself an inscribed sphere, on which the orbit of Mercury lies.
While writing, I may choose a clear Quartz Crystal for clarity or a yellow Fluorite octahedron to help keep creative thoughts flowing.
These are often known as the Platonic solids: the tetrahedron, cube, octahedron , dodecahedron and icosahedron.