 ### Beveled Tetrahedron

This form shows a tetrahedron (o) with its edges beveled by the trigonal tristetrahedron (l), and its… ### Combination of Tetrahedron and Rhombic Dodecahedron

A combination of a tetrahedron and a rhombic dodecahedron. ### Combination of Tetrahedron, Cube and Rhombic Dodecahedron

A tetrahedral combination. ### Combination of two Tetrahedra

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

Represents one way a tetrahedron and a cube might combine. ### Cube and tetrahedron

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

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

This form shows a cube modified by the tetrahedron. ### Tetrahedron From Octahedron

Illustration showing the derivation of Tetrahedron from an Octahedron. ### Regular Polyhedrons

Illustration of regular polyhedrons: tetrahedron, hexahedron, octahedron, dodecahedron, icosahedron. ### Two Similar Polyhedrons

Diagram used to prove the theorem: "Two similar polyhedrons may be decomposed into the same number of… ### Positive and Negative Tetrahedron in Combination

This form shows a positive and negative tetrahedron in combination. ### Regular Tetrahedron

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

This is a crystal of Sodium Chlorate, exhibiting the tetrahedron (-o) and the pentagonal dodecahedron… ### Various Solid Forms

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

"Isometric; tetrahedral. Tetrahedron form." — Ford, 1912 ### Sphere Inscribed in Tetrahedron

Illustration of a sphere inscribed in a tetrahedron. ### Sphere Inscribed in Tetrahedron

Illustration of a sphere inscribed in a tetrahedron. ### Tetrahedron

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

Principal forms of the isometric system: tetrahedron. ### Tetrahedron and cube

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

"The combination of tetrahedron and dodecahedron." — Ford, 1912 ### Tetrahedron and tristetrahedron

"A combination of tetrahedron and tristetrahedron." — Ford, 1912 ### Tetrahedron, Cube, and Dodecahedron in Combination

This form shows a tetrahedron (o), cube (h), and dodecahedron (d) in combination. ### Negative tetrahedron

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

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

"The tetrahedron is a form composed of four equilateral triangular faces, each of which intersects all… ### Positive and negative tetrahedrons

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

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