X-Ray Fluorescence Analysis of XII–XIV Century Italian Gold Coins

Abstract

An extensive analytical study has been performed on a large number of gold coins (Norman-Swabian Augustale and Tarì, Grosso of Lucca, Florin of Florence) minted in Italy from the end of XII century to XIV century. The X-ray fluorescence (XRF) technique was used for verifying the composition of the coins. XRF is a nondestructive technique particularly suited for in situ quantitative analysis of gold and minor elements in the precious alloy. The Florins turned out to have a gold content very close to 24 carats (pure gold) although in a couple of cases we observed relatively high concentrations of iron (around 2%) or lead (around 1%). The Grosso of Lucca has a similar composition, with a measured gold content around 97% due to a higher silver percentage (about 2%), with respect to the average Florin. The Augustali analyzed showed, on average, a gold content around 89%. The average gold content of the Tarì analysed is around 72%, with a relatively large variability. The analysis revealed the use of native gold for the coinage of the Florins, excluding the possibility of recycling gold coming from other sources. On the other hand, the variability observed in the compositions of the Tarì and Augustali could suggest the reuse of Islamic and North African gold. The study could shed some light on the sudden diffusion of gold coins in Italy around the first half of XIII century, allowing hypotheses on the provenience of the gold used for a coinage that dominated the economic trades from then on.

A Review of Energy Dispersive X-Ray Fluorescence (EDXRF) as an Analytical Tool in Numismatic Studies

“…An analytical study on a large number of gold coins (Norman-Swabian Augustale and Tarì, Grosso of Lucca, Florin of Florence, minted in Italy from the end of the 7th to the 9th century) was performed by Baldassarri et al 57 The quantitative analysis was performed by software using the Fundamental Parameters method. The analysis revealed the use of native gold for the coinage of the Florins, excluding the possibility of recycled gold coming from other sources.…”

X-Ray Fluorescence Analysis and Self-Organizing Maps Classification of the Etruscan Gold Coin Collection at the Monetiere of Florence

“…In our case, 13 different reference samples (six modern coins of known composition and seven samples specifically prepared by the Institute for Energetics and Interphases of CNR for a previous project) were used for calibration in the fundamental parameter method, to improve the accuracy of the quantitative results. 8 These samples covered a range of gold concentration between 200/1000 and 999.9/1000. The evaluated Etruscan coins were struck only on one side.…”

“…In recent years, XRF spectrometry has been used for the analysis of several numismatic collections. 3–8 The technique is nondestructive, fast, and works very well on archeological metal alloys. In particular, for the analysis of gold alloys, the lack of surface patina is a condition particularly favorable for the application of the XRF technique, 9 which is very sensitive to the presence of surface corrosion.…”

Analysis of Sagunto Ibero-Roman votive bronze statuettes by portable X-ray fluorescence

“…The study of archaeological bronze objects has consistently advanced in the last decades and, nowadays, a large number of results are available, especially concerning their composition and corrosion layers (Robbiola et al, 1998;Neff et al, 2013;Vasiliev et al, 2016), their manufacturing, authenticity and fabrication technology (Dungworth, 1997;Klemenc et al, 1999;Smith et al, 2011;Scott, 2013;Scuotto et al, 2014;Sorrentino et al, 2015), together with information about raw material provenance (Ferretti et al, 2007;Baldassarri et al, 2014).…”