Specific volumes of C60/C70 (3:1) fullerites are measured up to 330-degrees-C and 200 MPa using a dilatometer-type PVT (pressure-volume-temperature) apparatus. The compressibility and thermal expansion of fullerites are found to be much higher than those of graphite. This is consistent with a lower degree of molecular and supermolecular (crystal) packing in fullerites compared to graphite.