(Hemimorphic-tetartohedral).
Here the only element of symmetry is the tetrad axis. The pyramids of
the first {hhl}, second {hol} and third {hkl} orders have each only
four faces at one or other end of the crystal, and are hemimorphic.
All the simple forms are thus open forms.
Examples are wulfenite (PbMoO4) and barium antimonyl dextro-tartrate
(Ba(SbO)2(C4H4O6).H2O).