Considerable fine structure has been observed in the low energy 'true' secondary region of the secondary electron spectra of Mg. The effects on this fine structure of variations in primary electron energy (E_p), angle of incidence ( theta ) and the applied modulation are reported. In addition characteristic energy loss measurements have been made with the same parameters in order to see if any correlation exists between the two types of characteristic phenomena. A tentative explanation of the slow peak structure is given in terms of transitions between critical points in the band structure of Mg.