donor detonation in the storage container or a proximate storage container an improved explosive storage container and dynamic shock absorbing filler material combination provides a unique composite of graded pumice granules bound in a matrix and cast into the container the storage container and dynamic shock absorbing filler material provide an efficient safe and inexpensive storage container with a previously unattained margin of safety in the storage of explosives the storage containers may be constructed with any one of a number of different lateral and vertical spacings between the explosive media and thereby optimize the shock absorbing and damping effect for various overall sizes weights and capacities of storage containers the storage containers are readily and easily stacked and transported the disclosed filler material and composite have properties simulating those of an air entrained hardened foam material the cast composite has a relatively fine cellular structure and exhibits both the desired characteristics of shock dampening and rigidity the latter also exhibiting a tendency to dampen the propagation of fragments of the exploded donor round a preferred filler material is readily stabilized in combination with a casting plaster while specific embodiments have been shown and described many variations are possible the particular shape of the storage container including all dimensions may be changed to suit a particular explosive round the housing.