D.C. electrical conductivity of Ge-S and Ge-V-S glassysystems were studied. It was found that so called Mott minimum metallicconductivity is function of activation energy of d.c. electrical conductivityfor all studied glasses. The explanation based on idea of exponential tail ofvalence band edge and the p-type of electrical conductivity in extended statesclose to the mobility edge of vadence band was suggested.
