Examples from the Web for octahedral
Both "octahedron / octahedral" and "octohedron / octohedral" occur and have not been changed.A Guide to the Mount's Bay and the Land's End|John Ayrton Paris
Brass was decomposed, and its constituent copper crystallized in cubic and octahedral forms aggregated in beautiful branches.The San Francisco Calamity|Various
Sulphur exists in two well-known crystalline forms—rhombic, or octahedral, and monoclinic, or prismatic sulphur.The Phase Rule and Its Applications|Alexander Findlay
The octahedral cleavage of the diamond is taken advantage of in dressing the stone before cutting it.
Codeia is left in solution, and is obtained in octahedral crystals by spontaneous evaporation.