Particle fracture is the elementary process that governs comminution, Understanding this elementary fracture process is indispensable to the development of improved size reduction techniques. The Ultrafast Load Cell (UFLC), has been used to investigate the deformation and fracture of single particles subject to impact. The theoretical background of the measurements is presented in detail. The Ultrafast Load Cell allows the measurement of three fundamental deformation and fracture characteristics of particulate materials: the particle fracture energy, the particle strength and the particle stiffness, These measurements can be made under impact loading similar to the conditions in typical industrial ball mills. The effect of material type, particle size and particle shape on the three fundamental fracture characteristics of brittle materials is investigated. The fracture characteristics were found to be independent of the rate of strain at rates expected to be found in industrial comminution equipment. Two practical applications of the measurements are presented and the use of the Ultrafast Load Cell to study thermally assisted comminution of quartz is discussed in detail.