Ag, S, Ag + S, and S + Ag single and double ion implantations in silica glass were performed at room temperature. The implantation energies were chosen in order to get a projected range of 40 nm. The fluences were 2 × 1016 S+ cm−2 and 5 × 1016 Ag+ cm−2. Silver interacts weakly with the host silica matrix and forms essentially metallic clusters; this weak interaction between Ag and SiO2 induces formation of silver silicate rather than silver oxide. Double ion implantations of silver and sulfur lead to chemical interaction between the two species that is critically influenced by the implantation sequence. In particular, in the Ag + S sample silver and sulfur atoms react to form crystalline core (Ag)–shell (Ag2S) nanoclusters.