Provenance groups in a Roman jet jewelry collection at Aquincum (Budapest, Hungary) and comparison with jet and jet-like gemstones

Abstract

Jet and jet-like gemstones are found in graves from the Neolithic, but they became particularly popular during the Bronze Age and the Roman period. To discover their provenance, several techniques were used to determine distinctions between organic materials and occurrences. The present study utilized a combination of Fourier Transform Infrared spectroscopic (FTIR) and stable isotope ratio analyses to compare a unique Copper Age black bead („Lelle bead”) with Roman period jet items from the Aquincum Museum’s collection and known jet samples from various locations (UK, Spain, Turkey). Visual and multivariate statistical analyses of FTIR spectra, combined with H%, C%, and stable hydrogen and carbon isotope ratio determinations enabled us to distinguish significant (p < 0.1) groups among the Aquincum collection: „Lelle-type” samples, „Whitby-type” jets, shales, and coals. Some gemstones were positively identified as Whitby jet, whereas some of the others were indistinguishable from the Lelle bead. This study shows that the coupled FTIR and stable isotope analyses can potentially be used to determine the provenance of archaeological artifacts.