Octahedral \Oc`ta*he"dral\, a. [See {Octahedron}.] Having eight faces or sides; of, pertaining to, or formed in, octahedrons; as, octahedral cleavage. {Octahedral borax} (Chem.), borax obtained from a saturated solution in octahedral crystals, which contain five molecules of water of crystallization; distinguished from common or prismatic borax. {Octahedral iron ore} (Min.), magnetite.