A general mixture rule, which has the correct type of phase symmetry, is proposed for estimating the properties of composites having two continuous phases. The form of this equation is different from the equations used to predict the properties of composites with one continuous phase and one dispersed phase. The proposed equation for property P is
where the volume fractions of components A and B are øA and øB, respectively, and n is a constant. A simple model is used to correlate the morphology of systems having two continuous phase with the parameter n of the mixture rule. The connectivity of the phase varies with concentration. The properties, such as elastic modulus, depend primarily upon the modulus of the material with the higher modulus. In general, the properties depend very little on the morphology of the system.