ASYMMETRIC CLASS (Hemihedral, Pediad.) Crystals of this class are devoid of any elements of symmetry. All the forms are pedions, each consisting of a single plane; they are thus hemihedral with respect to crystals of the last class. Although there is a total absence of symmetry, yet the faces are arranged in zones on the crystals.
Examples are calcium thiosulphate and hydro gen strontium dextro-tartrate ( ; there is no example known amongst minerals.