Obsidian provenance determination

FIGURE 22 Obsidian in the eastern Mediterranean Sea area. Studying the relative concentration of trace elements in obsidian makes it possible to identify the obsidian and to determine its provenance. Determining the relative amounts of barium and zirconium in ancient obsidian tools and in samples from different sources of the natural glass, for example, made it possible to identify the provenance of obsidian used in eastern Mediterranean Sea area sites (Renfrew and Dixon 1976). 

Yegingil, Z. and T. Lunel (1990), Provenance studies of obsidian artifacts determined by using fission track ages and trace element analysis, Nucl. Tracks Rad. Meas. 17(3), 433. 

Kilikoglou, V., Bassiakos, Y., Doonan, R.C. and Stratis, J. (1997). NAA and ICP analysis of obsidian from Central Europe and the Aegean source characterisation and provenance determination. Journal of Radioanalytical and Nuclear Chemistry 216 87-93. 

Since the mid-1960s, a variety of analytical chemistry techniques have been used to characterize obsidian sources and artifacts for provenance research (4, 32-36). The most common of these methods include optical emission spectroscopy (OES), atomic absorption spectroscopy (AAS), particle-induced X-ray emission spectroscopy (PIXE), inductively coupled plasma-mass spectrometry (ICP-MS), laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS), X-ray fluorescence spectroscopy (XRF), and neutron activation analysis (NAA). When selecting a method of analysis for obsidian, one must consider accuracy, precision, cost, promptness of results, existence of comparative data, and availability. Most of the above-mentioned techniques are capable of determining a number of elements, but some of the methods are more labor-intensive, more destructive, and less precise than others. The two methods with the longest and most successful histoty of success for obsidian provenance research are XRF and NAA. 

This study has demonstrated that precise chemical analysis is a powerful tool for the characterization and provenance determination of Middle Eastern obsidian. Thirteen to 15 chemically distinctive groups were distinguishable in geological source samples collected from eight source... 

Earlier it was stated that provenance determination is inherently more complex for pottery than for obsidian. In general, pottery itself rather than clay is used as source material to establish the composition of pottery that was made locally. 

In 2006, a table-top energy-dispersive XRF (ED-XRF) spectrometer was acquired by the Archaeometry Lab to facilitate non-destructive analysis of obsidian and other types of artifacts. One of the first projects performed on the new XRF spectrometer was the re-analysis of the geological samples from sources in Peru. As a result, it is now possible for the Archaeometry Lab to use either XRF or NAA to successfully determine the provenance of obsidian artifacts from Peru. Due to its light weight, the spectrometer also has the potential to be transported from the laboratory to museums and to archaeological sites for in situ analysis. 

The use of trace element analysis to determine the provenance of archaeological materials has expanded rapidly in the last decade. It is now a well-established technique for the identification of obsidian source deposits (J), and is nearly as established for turquoise (2), steatite (3), and some ceramic materials (4). Native copper has received much less attention. Friedman et al. (5), Fields et al. (6), and Bowman et al. (7) used trace element analyses to determine the type of geological ore from which copper was extracted. However, only our efforts (8) and the work of Goad and Noakes (9) have focused on collecting and analyzing native copper from all potential deposits of a given region to provide a data base for statistical comparison with artifact trace element compositions. 

Sixty-one obsidian artifacts from four Early Neolithic sites were selected for chemical analysis. The analysis of significant-sized assemblages from single cultural periods allows direct comparison between contemporary sites in different geographic locations. Many early provenance studies, however, relied on very few artifacts from individual sites so that such patterns in the exploitation of specific obsidian sources could not be determined (75). 

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