A combination of a tetrahedron and a rhombic dodecahedron.

"...a combination of these two tetrahedra, and represents a crystal of blende, in which the four larger…

"A combination of cube and tetrahedron. It will be noted that the tetrahedron faces truncate the alternate…

"A combination of cube, dodecahedron, and tetrahedron." — Ford, 1912

Illustration of regular polyhedrons: tetrahedron, hexahedron, octahedron, dodecahedron, icosahedron.

Diagram used to prove the theorem: "Two similar polyhedrons may be decomposed into the same number of…

"Science has succeeded in classifying the thousands of known crystals in six systems, to each of which…

Illustration containing a tetrahedron, hexahedron, octahedron, dodecahedron, and icosahedron, placed…

"This is bounded by four equilateral triangles and is identical with the regular tetrahedron of geometry."…

"A combination of cube and tetrahedron. It will be noted that the tetrahedron faces truncate the alternate…

"The tetrahedron is a form composed of four equilateral triangular faces, each of which intersects all…

Pattern that can be cut out and folded to construct a regular tetrahedron. Fold on the dotted lines,…

"The tetrahedron is a form composed of four equilateral triangular faces, each of which intersects all…

"If a positive and negative tetrahedron occured together with equal development, the resulting crystal…

Diagram used to prove the theorem: "Two tetrahedrons having a trihedral angle in each equal, are to…