In the shape of a rhombohedron. The rhombohedral (trigonal) crystal system. Minerals may have a rhombohed ral crystal form, or may have rhombohedral cleavage. Calcite is an example of a rhombohedr al crystal with rhombohedral cleavage.

(rhom-bo-he´-dral) Pertaining to or crystallizing in rhombohedrons. System: a division of the hexagonal system in which the unit cell is a rhombohedron.

Related to the rhombohedron; presenting the form of a rhombohedron, or a form derivable from a rhombohedron; relating to a system of forms including the rhombohedron and scalenohedron.

Resembling a prism with six four-sided facets.

having three-fold symmetry

NEED A DEFINITION.