Establishing the Baltic origins of archaeological amber beads from Dura-Europos (Syria) using non-destructive DRIFTS

Abstract

Sourcing archaeological amber has hitherto been limited by a reliance on chemical techniques that require some degree of destructive sampling. The majority of amber artifacts are friable, weakened after millennia spent unprotected from environmental stressors, and as such are especially vulnerable during analysis or even sampling. Here, we assess the capability of an entirely nondestructive analytical technique — Diffuse Reflectance Infrared Spectroscopy (DRIFTS) — to scientifically identify archaeological Baltic amber. Using a reference collection of geological amber specimens, our direct comparison of DRIFTS spectra to those collected via conventional transmission FTIR, which necessitates destructive sampling, demonstrates the validity of the new technique. Thirteen beads from the archaeological site of Dura-Europos in Syria were subsequently analyzed using DRIFTS alone. Five of the beads showed spectral features indicative of Baltic amber, whereas the others were too degraded to yield diagnostically measurable spectra. Our study thus confirms the capability of the DRIFTS technique to analyze whole, untreated amber artifacts when their integrity is of high concern. Furthermore, our results indicate a previously unestablished connection between Dura-Europos and northern Europe during the first two centuries CE through long-distance exchange networks stemming from the Mediterranean basin.