a triangular pyramid, as a form in certain calcareous spars.

A solid figure having 24 faces, every three of which correspond to one face of an octahedron: either with triangular faces (= triakisoctahedron at tri…

= tetrakis-hexahedron, n.

Crystallography. A wedge-shaped crystal bounded by four equal and similar triangular faces.

A crystal form consisting of two scalenohedra (mirror images of each other) sharing the same base.

Crystallography. An open form consisting of three or more planes that meet in edges parallel to the vertical axis of the crystal.

A solid figure contained by twenty-four equal triangular planes, having the appearance of a cube with a low pyramid raised on each of its six…

Crystallography. (See quot. 1882)

a prism of an orthorhombic crystal between the macropinacoid and the unit prism.

An imperfect form; Crystallography, a hemihedral form.

a tetartohedral crystal.

A solid body bounded by forty-eight triangular planes; also called hexakisoctahedron n. at hexakis-, comb._form affix, octakis-hexahedron, tetrakonta-…

Botany. (See quot. 1900.)