This invention relates to solid solutions containing (a) about 90 to about 10% by weight of a chlorinated copper phthalocyanine containing about 14 to about 16 atoms of chlorine per molecule and (b) about 10 to about 90% by weight of a copper phthalocyanine containing about 3 to about 4 atoms of chlorine wherein said compositions are characterized by X-ray diffraction patterns that differ from the sum of the X-ray diffraction patterns of the individual components.