A study on gold and copper provenance for Romanian prehistoric objects using micro-SR XRF

Abstract

This study intends to clarify the metal provenance of gold archaeological items using the variation of the Au-Ag ratio and the presence of trace elements as Sn, Sb, Te, and Pb, concentrating on gold Dacian Koson coins, recovered recently. It also extends the area of our investigations to the copper provenance of Bronze Age artifacts-axes, sickles, and celts-found on Romanian territory. The experiments were performed by micro-SR XRF at BESSY Berlin, at the BAM-line facility. Two types of coins (Koson, with and without monogram) were analysed. The conclusions we reached were that most of the monogram coins are made from refined gold (3-5% Ag, less than 0.5% Cu), while the without monogram coins are made from native Transylvanian gold (9-20% Ag, 0.5-2% Cu), of alluvial origin, proved by the presence of Sn, Sb and Te embedded in the gold. The problem of provenance for prehistoric Romanian copper and bronze objects consists in linking their elemental compositional patterns to the ones of the Bronze Age regional mines from Bulgaria, Serbia or Transylvania, most likely used as ore sources for their manufacture. The studied samples present relevant traces of As, Ag, Sb, and Co, suggesting the most probable use of copper from Serbia or northern Bulgaria for their manufacture.

Atomic spectrometry update. Industrial analysis: metals, chemicals and advanced materials

“…A number of the more interesting articles are noted below. Constantinescu et al 38 employed m-SR XRF spectrometry to measure the trace elements in gold and copper Romanian archaeological items to clarify their provenance. The elemental evidence from the gold coins (Pb, Sb, Sn and Te) indicated that the gold coins with a monogram were made from refined gold and the ones without a monogram were made from native (alluvial) Transylvanian gold.…”

X-ray microscopy reveals the outstanding craftsmanship of Siberian Iron Age textile dyers

“…X-ray fluorescence microscopy ( µ -XRF) is an ideally suited technique for high-resolution imaging of metal based pigments. Its outstanding capabilities in terms of spatial resolution and elemental sensitivity have been demonstrated for the analysis of pigments in cultural heritage samples, such as masterpiece paintings 6 – 8 , handwritings 9 , 10 , metal artefacts 11 , 12 and other solid objects 13 . Here, we present the first study employing high-resolution µ -XRF for the in-situ analysis of pigments within a textile sample with high historical relevance.…”

µ-XRF Studies on the Colour Brilliance in Ancient Wool Carpets

“…A suitable method for quantitative element-specific analyses with high spatial resolution is X-ray fluorescence microscopy ( μ -XRF) [ 16 – 18 ]. The method has proven its value for elemental mapping in cultural heritage studies, regarding, for example, paintings [ 19 – 22 ], inks [ 23 , 24 ], and solid objects [ 25 , 26 ], and also enables a detailed investigation of oxidation states by performing X-ray absorption near edge spectroscopy (XANES) [ 27 – 31 ]. Although many biological tissues are prone to decomposition upon X-ray radiation [ 32 – 34 ], sheep wool and other keratin based biofibres are relatively stable to significant X-ray doses and are not expected to be structurally destroyed during standard μ -XRF mapping [ 35 ].…”