Crystallography. Designating a fundamental crystalline form or structural unit from which all others may be derived geometrically (originally a…

In various specific contexts. Crystallography. Designating a group of atoms within a crystal which form a parallelepiped composed of tetrahedrons…

Crystallography. In Haüy's nomenclature: designating minerals displaying truncated bipyramidal or rhomboidal forms with terminal facets perpendicular…

= emarginate, adj.

spec. Of a crystal: having some faces plane and others convex. Obsolete. rare.

Crystallography. = primitive, adj. 10. Cf. secondary, adj. 3i. Obsolete.

(See quot.)

designating a space lattice whose points occur at the centres of the faces and at the corners of unit cells; (of a crystal, substance, etc.) having…

designating a lattice structure in which an atom or ion occurs at each corner and in the centre of a cubic unit cell; having such a structure; cf. fa…

Crystallography. Characterized by or relating to small blocks of perfect lattices set at very slight angles to one another.