Universal infrared conductivity of graphite

The conductivity of graphite is analytically evaluated in the range of 0.1-1.5 eV, where the electron relaxation processes can be neglected, and the low energy excitations at the "Dirac" points are most essential. The value of conductivity calculated per one graphite layer is close to the universal conductivity of graphene. The features of the conductivity are explained in terms of singularities of the electron dispersion in graphite.