Tracing the Resources of Iron Working at Ancient Sagalassos (South‐west Turkey): A Combined Lead and Strontium Isotope Study on Iron Artefacts and Ores*

Abstract

Lead and strontium isotope analyses were performed by thermal ionization mass spectrometry (TIMS) on Roman to Byzantine iron artefacts and iron ores from the territory of ancient Sagalassos (south-west Turkey), to evaluate Pb and Sr isotopes for provenance determination of ores for local iron production. It can be demonstrated that for early Roman artefacts and hematite iron ore processed in early Roman times from Sagalassos proper, as well as for magnetite placer sands and early Byzantine raw iron from the territory of the city, Sr isotopes are much less ambiguous than Pb isotopes in providing clearly coherent signatures for ore and related iron objects. Late Roman iron objects were produced from iron ores that as yet remain unidentified. Early Byzantine iron artefacts display more scatter in both their Pb and Sr isotope signatures, indicating that many different ore sources may have been used. Our study demonstrates that iron objects can be precisely analysed for their Sr isotopic composition, which, compared to Pb isotopes, appears to be a much more powerful tool for distinguishing between chronological groups and determining the provenance of raw materials.

Combined Pb–Sr isotopic analysis in provenancing late Roman iron raw materials in the territory of Sagalassos (SW Turkey)

“…Two late Roman iron artefacts from Sagalassos were re-analysed for their Pb-Sr isotopic composition. Sample SA00LL5 is an iron nail, sample SA03NK145 an arrow head (Degryse et al 2007). …”

“…In an earlier study, lead and strontium isotope analyses were performed by thermal ionisation mass spectrometry on early Roman to early Byzantine iron artefacts and iron ores from the territory of the town. The use of Pb and Sr isotopes for provenance determination of the ores used for local iron production was thus evaluated (Degryse et al 2007). It was demonstrated that the ore source for early Roman artefacts from Sagalassos was hematite iron ore from an ore deposit in the Lycean limestone nappes, just north of the ancient town, and that magnetite placer sands were used for early Byzantine raw iron production in the territory of the city at Dereköy (Fig.…”

“…Ferrer Eres et al 2008). The intention of the use of the radiogenic isotope technique presented here is to falsify a direct relation between a raw material and a finished product, as radiogenic isotope analyses offer a solution to the problem of chemical fractionation (Gale et al 1990;Schwab et al 2003;Degryse et al 2007). …”

“…1). Sr isotopes proved much less ambiguous than Pb isotopes in providing clearly coherent signatures for ore and related iron objects (Degryse et al 2007). While lead isotopic signatures of artefacts and ores may be ambiguous due to the often highly variable chemistry of the raw materials, 87 Sr/ 86 Sr ratios may represent a more straightforward tool to exclude or corroborate specific point sources of ores used for metal production.…”

“…As the deposit is situated close to the southern border of the territory of Roman Sagalassos, along good communication and transport ways, these deposits are evaluated as a possible source for the late Roman and early Byzantine iron at Sagalassos. Iron artefacts of that time were analysed again for their Pb and Sr isotopic signatures (duplicating analyses from Degryse et al 2007) and were compared to Pb-Sr isotopic analysis of suitable iron ores from Camoluk.…”