Hexagonal diamond grains of similar to 30 nm diameter together with graphite and SiC are seen in predominantly amorphous carbon films deposited at low temperature on Si substrates from a CH4 plasma vapour source. The different crystalline phases are identified by grazing-angle X-ray diffraction which allows for substrate rotation and tilting to enable the 2 theta peaks to be. correlated with the angular displacements of specific planes. Electron energy-loss spectroscopy shows the chemical composition of the films to be predominantly carbon with traces of oxygen. Raman spectroscopy shows the peaks to be associated with amorphous carbon and graphite, together with a peak at 1170 cm(-1) which is attributed to microcrystalline hexagonal diamond.