Detailed analysis of the room temperature X-ray powder diffraction data of pure solid C70 is reported. C70 prepared by slow evaporation from toluene solution adopts an hcp structure (space groupP63/mmc) witha=10·53(1) A andc=17·24(1) A. C70 sublimed on to Si wafer adopts an fcc structure witha=14·89(1) A. The occurrence of both the hcp and fcc phases is rationalized in terms of cohesive energy calculations. Theoretical calculations of the diffraction pattern for the hcp structure, taking into account (a) orientational disorder amongst the molecules (b) presence of stacking faults and (c) a fraction of the sample to be amorphous/microcrystalline is seen to provide very good agreement with the experimental diffraction pattern.