### 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…