The Obsidian Trade in Prehistoric Italy: Reconstructing Social and Economic Organization by Modeling Exchange

The analysis of several hundred pieces of archaeological obsidian by electron microprobe and laser ablation mass spectrometry makes possible the reconstruction of socio-economic organization in prehistoric Italy through the use of trade models. Although it has been more than 25 years since Cann and Renfrew introduced the use of elemental analysis for determining the provenance of obsidian artifacts, the study presented here is the first major attempt to model obsidian exchange in the western Mediterranean. The measurement of either minor or trace elements has been found sufficient to differentiate the island sources of Lipari, Palmarola, and Pantelleria, and the multiple flows of Monte Arci in Sardinia. The analysis of statistically significant samples from a large number of sites allows for the study of exchange systems in discrete spatial zones during specific time periods.

Distribution patterns for six cultural periods, beginning about 6000 BC, have been determined for Sardinia, Corsica, France, Italy, Sicily and North Africa. These data are then tested using mathematical models developed by Hodder and Renfrew to determine fall-off rates of obsidian frequency in these regions. In addition to comparison with other prehistoric exchange systems, these models are used to infer diachronic changes in social organization and to test hypotheses regarding the development of politically constrained economic networks. The data are also used to indicate which sites may have served as redistributive centers, and to identify preferential trade routes between the island sources and mainland settlements.