We have measured the electrical conductivity of mixtures of hard, insulating and conducting particles, as a function of the fraction p of conductors. We observe the existence of a threshold p c , below which the mixture is not conducting – a phenomenon of s i t e p e r c o l a t i o n in an irregular lattice. The value of this threshold (p c ?0.3), relatively insensitive to particle shape (spherical, oval, or baroque) or to applied pressure, is interpreted as being due to a relatively constant average number of nearest neighbor contacts (z?6−7), reminiscent of ’’loose‐packing’’. While the above results have been obtained with macroscopic mixtures (particle size ?5mm), we report as well on experiments on microscopic powders, currently in progress. We find, on the other hand, that pressure and the shape of the container do affect the conductance function G (p), above the threshold. Specifically in the region p?1, the slope of the normalized conductance G(p)/G(1) varies inversely as the applied pressure. We interpret this as a superposition of a b o n d p e r c o l a t i o n phenomenon on the original s i t e problem, where the applied pressure governs the probability p B of existence of good bonds.