Obsidian chemical characterization

Erickson, J.E. 1981. Exchange and production systems in Californian prehistory The results of hydration dating and chemical characterization of obsidian sources. British Archaeological Reports International Series, 110, 1-240. 

Use of inductively coupled plasma-mass spectrometry (1CP-MS) coupled to a laser-ablation sample introduction system (LA-ICP-MS) as a minimally destructive method for chemical characterization of archaeological materials has gained favor during the past few years. Although still a relatively new analytical technique in archaeology, LA-ICP-MS has been demonstrated to be a productive avenue of research for chemical characterization of obsidian, chert, pottery, painted and glazed surfaces, and human bone and teeth. Archaeological applications of LA-ICP-MS and comparisons with other analytical methods are described. 

Inductively coupled plasma-mass spectrometry (ICP-MS) has been utilized as a bulk technique for the analysis of obsidian, chert and ceramic compositional analyses 12-14). However, due to the high level of spatial variation of ceramic materials, increased sample preparation is necessary with volatile acids coupled with microwave digestion (MD-ICP-MS) to properly represent the variability of ceramic assemblages IS, 16). Due to the increased sample preparation and exposure to volatile chemicals, researchers have continued to utilize neutron activation analysis (INAA) as the preferred method of chemical characterization of archaeological ceramics (77). 

In summary, we have determined LA-ICP-MS analysis to be an accurate and precise instrumental technique for chemical characterization of obsidian artifacts and source samples. We have developed two methods for normalization and standardization of obsidian data that while different, permit LA-ICP-MS data to be transformed to abundance data and that data derived by LA-ICP-MS conq>ares favorably to INAA data. The minimal sanq>le preparation time, the ability to select the suite of elements that will be analyzed, and the rapid analytic time make LA-ICP-MS, a minumUy invasive, cost-effective method for characterizing obsidian. 

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... 

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