  Measurements of the basal-plane resistivity rho_a(T,H) performed on highly
oriented pyrolitic graphite, with magnetic field H parallel to the c-axis in
the temperature interval 2 - 300 K and fields up to 8 T, provide evidence for
the occurrence of both field - induced and zero-field superconducting
instabilities. Additionally, magnetization M(T,H) measurements suggest the
occurrence of Fermi surface instabilities which compete with the
superconducting correlations.
