We study the linearlized stability of the state of uniform fluidization, within the context of the theory of mixtures. The mixture is assumed to be made up of a classical linearly viscous fluid infused with particles. In marked departure from most of the previous studies, we model the solid as a granular material and assume a constitutive relation that stems from classical motions in continuum mechanics. The linearized stability analysis of the state of uniform fluidization, in general, for a three-dimensional disturbance leads to an eighth order equation for the characteristic whose root implies instability, when positive.