Rapid Chemical Characterization of Obsidian Artifacts by Electron Microprobe Analysis

Abstract

The potential of the electron microprobe to analyse chemically obsidian artifacts for source provenance studies is demonstrated using artifacts from four archaeological sites in Kenya.

Characterization of the Monte Arci (Sardinia) Obsidian Sources

“…Electron microprobe analysis using wavelength dispersive X-ray spectrometers (WDS) was thus selected as the method of choice for characterizing geological specimens and analysing large numbers of archaeological artefacts since only a tiny 1-2 mm sample is needed, sample preparation is minimal, analytical precision is superior to laser ablation ICP-MS, and the per-sample cost is a fraction of the price of XRF or NAA. The microprobe (or scanning electron microscope) with energy dispersive spectrometers (EDS) has been used for obsidian studies in Europe (Biró & Pozsgai, 1984;Biró, Pozsgai & Vlader, 1986), the Near East (Keller & Seifried, 1990), and East Africa (Merrick & Brown, 1984;Merrick, Brown & Nash, 1994), but it must be noted that, for most obsidians, TiO 2 , MgO, MnO, P 2 O 5 , and BaO are usually below the minimum detection limits of SEM or microprobe EDS systems. Since TiO 2 , MgO, and BaO are important for discriminating among the Mediterranean obsidian sources, WDS is necessary for provenance studies in this region (see Verità et al, 1994 for a comparative study of EDS and WDS).…”

Investigating Activity Patterns In Prehispanic Plazas: Weak Acid‐Extraction ICP–AES Analysis of Anthrosols at Classic Period El Coyote, Northwestern Honduras

“…Middens produced from lithic manufacturing activities might be expected to have elevated concentrations of Fe, Ti, Al and K, related to the deposition of phenocrysts and microphenocrysts (i.e., quartz, potassium feldspar, iron oxide, titanium dioxide and ferromagnesian minerals) that compose volcanic glass and some types of cryptocrystalline materials (e.g., Merrick and Brown 1984). Food‐production middens should have elevated concentrations of P and Ca, produced from the deposition of faunal bones and other organic remains (e.g., Terry et al 2000), as well as K and Na related to the deposition of wood ash associated with cooking fires (e.g., Middleton and Price 1996).…”

Long distance trinket trade: Early Bronze Age obsidian from the Negev

“…Given the glossy, homogeneous nature of obsidian, X-ray analysis using the electron microprobe is a good alternative analytical technique for sourcing since only a tiny 1-mm sample is required for quantitative analysis, the instrumental cost is on the order of only five U.S. dollars per sample, and a batch of 18 samples can be prepared and analyzed in several hours. This technique has been used for obsidian sourcing in Europe [7], the Mediterranean [61,62], Anatolia [33], and East Africa [41,42].…”