he dependence of the temperature of minimum electrical resistivity on the size of the mosaic blocks of artificial graphite of GMZ grade based on isotropic coke was calculated. A chain model of the electrical connection of lamellar structural elements (graphite flakes) was used. Compliance of the calculated results with Mason’s empirical formula was shown. Two cases were considered: the case of independence of the dimensions of mosaic blocks and the anisometry of the lamellar structural elements and the case when the dimensions of the mosaic blocks were proportional to the anisometry of the lamellar structural elements.