The ability of explosives to fragment rock has been assessed in small scale trials at the Granite Rock quarry, Baimsdale, Victoria. Three 65 mm diameter holes were fired simultaneously in a five metre bench, and the rock collected, screened and weighed. The mass of fines increased as the explosive strength increased in the series 30(10 ANFOPS <50 50 anfops>< ANFO< ANGD 95. A linear correlation between fines production and Effective Energy was found. The fines appear to be generated around the borehole since their mass remained constant as the pattern was expanded. Strong decoupling of the explosive charge only slightly reduced the mass of finest material, but did significantly reduce the amount of coarse material. Increasing the timescale of energy delivery improved fragmentation. Detonation velocities were measured routinely as a check on explosive performance. The ICI optical fibre point-to-point system and the BHP continuous coaxial cable SLIFER system gave very similar results. Face velocities were measured using high speed filming techniques, and a novel sliding magnet/coil technique. Explosive energy correlated well with (face velocity)2.