The morphological changes which take place in silver foils placed in microwave generated argon plasmas can be fully explained on the basis of earlier developed models of ionic sputtering. In contrast, morphological changes in oxygen plasmas were found to be complex and not readily explained by earlier models. Morphological changes were found to be a function of the foil position within the plasma, and thus were clearly influenced by plasma species concentrations and temperature. In environments containing oxygen atoms and no charged species the only change which occurred was a very slow rate of silver oxide growth. In environments containing modest concentrations of charged particles and oxygen atoms extremely rapid oxidation took place. In environments containing high concentrations of radical and charged particle species several unprecedented phenomena were observed. First, silver oxide films were found to be stable at temperatures far above the conventionally calculated decomposition temperature. Second, extremely high etch rates were sometimes observed. Third, the nature of the morphological changes could not be fully predicted, as results varied from sample to sample.