It is believed [1, 2] that at sufficiently low loading levels, rocks behave as elastic solids, which are capable of dissipating deformation energy only at pressures that lead to the occurrence of an irreversible deformation component due to transition to a plastic state or due to damage. It is shown below that in dynamic loading. irreversible energy absorption is also observed under loads that are significantly lower than the elastic limit. and this can be associated with both viscosity and changes in the internal structure of rocks.The general mechanism of variation in the energy capacity of dynamic deformation with variation in loading intensity and conditions is established on the basis of experiments with various intrusive rocks (granites, granodiorites, granite-gneiss, etc.). Qualitative data on the dissipation of dynamic-loading energy in the regions of quasi-elastic and elastoplastic deformation of intrusive rocks are compared.Rocks are complex deformable media. This complexity is due to the features of their physical state (polymineral composition, heterogeneity, multiphase and granular structure, porosity, structural strength. etc.), which affect the deformation process from the very beginning of loading and which are reflected on the shape of strain diagrams. Since the overwhelming majority of rocks undergo compression loads, the discussion below is concerned with this type of dynamic load. At the beginning of loading, partial closure of pore space (microdefects) [3] has an effect on the stress-strain relationship, causing nonlinearity of strain diagrams in the region of low pressures. Under sufficiently large loads, the strain of the mineral rock material exceeds considerably the strain of the pore space, and the behavior of the rock becomes nearly linear-elastic. As microdefects are accumulated or the plastic-strain component increases, a departure from this behavior is observed at stresses comparable with the ultimate or yield stresses. Figure 1 shows a(e) diagrams for uniaxial dynamic (a) and static (b) compression. The diagrams are plotted on the basis of experimental studies of rocks of various origins performed on a measuring complex [4]. Curve numbers 1-6 correspond to the ordinal numbers of rocks from some deposits of refractory and nonmetalliferous raw materials and also of the natural gas of Ukraine in Table 1, which gives brief data on their physicomechanical properties: density p, porosity n, longitudinal elastic wave velocities Vlong , Poisson's ratio v, and strength in uniaxial static compression strength a0-These diagrams reflect the results of experiment in which the occurrence of the irreversible component of the deformation process was ruled out, i.e., the state of the rock was within the elastic region. However. although the behavior of all type of rock is generally elastic (the unloading curve returns to the coordinate origin), the loading trajectory does not coincide with the unloading trajectory, and ~rnax 0(1) 0 ~max which indicates pulsed-energy absorption. Here a and ~ are th...