INVESTIGATIONS TOWARDS THE HYDRATION DATING OF AEGEAN OBSIDIAN

Abstract

Obsidian from the Melos source area (the sources of Adamas and Demenegaki) is one of the most widely distributed natural glasses in the Acgean region and potentially a powerful chronological tool for the study of regional archaeological sequences. However, the usefulness of the Melos obsidian and lesser sources for hydration dating has never been explored. In this paper, we have conducted a series of analyses to assess the weathering characteristics of three obsidian sources (Melos, Yiali, Antiparos). Infrared spectroscopy and heavy-liquid density measurements have demonstrated that Melos and Antiparos obsidians contain little structural water (0.11-0.13%) while the Yiali source shows a large range (0.09-0.59%), Consequently, hydration rates willbe highly variable for some non-Melos glasses.In microscope thin-section, the hydrated surfaces on Melos obsidian tend to be optically weak and poorly defined therefore making precise measurements difficult. However, the measurement of hydrated surface by secondary ion mass spectrometry (SIMS) and infrared photoacoustic spectroscopy(IR-PAS) has the potential to produce precise thickness determinations that can be used in the dating process.