This form is bounded by forty-eight similar scalene triangles. Its solid angles are of three kinds: six octahedral, at the extremities of the principal axes; eight hexahedral, at the extremities of the trigonal axes; and twelve tetrahedral, at the extremities of the digonal axes. Naumann’s symbol for this form is m 0 n; Dana’s, m-n.
George Huntington Williams, Ph.D. Elements of Crystallography for Students of Chemistry, Physics, and Mineralogy (New York, NY: Henry Holt and Company, 1892)