c-SiO2 samples were implanted with Ag+ at an energy of 200 keV to doses in the range of 2.3-9 x 10(16) ions/cm(2) at room temperature. At a dose of 6.7x 10(16) ions/cm2, the transmission electron microscopy image shows that the implanted layer consists of two major sizes of nanoclusters: the large clusters, found in the deeper layer, are about 20 nm in diameter; the smaller clusters, found near the surface, are about 5 nm in diameter. At the relatively low dose of 2.3 x 1016 ions/cm2, there is only one optical absorption band caused by surface plasmon resonance. At a higher dose, a splitting of the absorption band and the redshift are attributed to a dipole interaction between nanoclusters for a high density of nanoclusters.