A sample of 210 pieces of archaeologically derived obsidian from settlement sites in Palliser Bay, New Zealand, was subjected to X-ray fluorescent analysis, in order to define the petrographic sources exploited by these prehistoric groups. It was found that the material had been derived from sources at Mayor Island, Huruiki, Rotorua, Cooks Bay, Purangi, Ongaroto and Taupo, and with the exception of the last 3, all were being quarried as early as the 12th century A.D. Problems were encountered in assessing the significance of trends in source exploitation which had been proven on other grounds, and these suggested that future analyses must involve far larger archaeological samples.