Irradiation-induced processes are often considered only in their nonequilibrium aspects. The purpose of this brief review is to show that chemistry, and particularly redox properties, play a major role in the thermal evolution of such systems and generally cannot, therefore, be neglected. This is exemplified by the synthesis of Ag nanoclusters in glasses and silica, under both low (gamma-ray) and high (MeV ion) deposited energy density irradiation conditions. The nanocluster formation mechanism is shown to be similar to the latent image formation process in photography. The corresponding information was used to control nucleation and growth of PbS clusters in glasses, leading to promising optical properties. In the course of these studies, we also showed that lognormal size distributions characterize the absence of information on the nanocluster formation process.