(Hemimorphic-hemihedral).
Here there are two pairs of vertical planes of symmetry intersecting
in the tetrad axis. The pyramids {hhl} and {hol} and the bipyramid
{hkl} are all hemimorphic.
Examples are iodosuccimide (C4H4O2NI), silver fluoride (AgF.H2O), and
penta-erythrite (C5H12O4). No examples are known amongst minerals.