Non-destructive characterization of archeological Cu-based artifacts from the early metallurgy of southern Portugal

Abstract

In this study, Monte Carlo (MC) simulations combined with energy dispersive X-ray fluorescence (EDXRF) spectroscopy have been used to characterize nondestructively a collection of Cu-based artifacts recovered from two archeological sites in southern Portugal: (a) the Chalcolithic E.T.A.R. site of Vila Nova de Mil Fontes and (b) the Middle Bronze Age site of Quinta do Estácio 6. The metal artifacts show a multilayered structure made up of three distinct layers: (a) brownish carbonate soil-derived crust, (b) green oxidized corrosion patina, and (c) bulk metal. In order to assess the reliability of the EDXRF-based Monte Carlo simulations to reproduce the composition of the alloy substrate in archeological bronze artifacts without the need to previously remove the superficial corrosion and soil derived patinas, EDXRF analysis together with scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) was also performed on cleaned and patina-/crust-coated areas of the artifacts. Characterization of the mineralogical composition of the corrosion products in the surface patinas was further determined by means of X-ray diffraction (XRD). Results suggest that the adopted EDXRF/Monte Carlo protocol may represent a safe and fast analytical approach in the quantitative characterization of the bulk chemical composition of Cubased metal artifacts even in the presence of fairly thick corrosion patinas and/or soil-derived encrustations at the surface of the archeological objects.

Elemental characterisation of a collection of metallic oil lamps from South-Western al-Andalus using EDXRF and Monte Carlo simulation⋆

“…Large differences in the Zn content have been detected as well, with values ranging from 2.35% (C5) to 15.47% (C1). From the EDXRF/MC protocol point of view, the systematic occurrence of Zn is a novelty when compared with previous case studies adopting the same quantitative approach [41][42][43]. Indeed, the presence of Zn represented a hard task due to, on the one side, an anomalous change of the Zn-K peaks and the simultaneous presence of intense Cu-K peaks on the other.…”

Use of Monte Carlo Simulation as a Tool for the Nondestructive Energy Dispersive X-ray Fluorescence (ED-XRF) Spectroscopy Analysis of Archaeological Copper-Based Artifacts from the Chalcolithic Site of Perdigões, Southern Portugal

“…Indeed, ED-XRF-MC protocol has already been applied in the analysis of metals covered by different corrosion products, such as oxides like cuprite (Cu 2 O) and tenorite (CuO), such carbonates as malachite (Cu 2 (CO 3 ) 2 (OH) 2 ) and cerussite (PbCo 3 ), sulfates like brochantite (Cu 4 SO 4 (OH) 6 ), and chlorides paratacamite (Cu 2 Cl(OH) 3 ) and atacamite (Cu 2 Cl(OH) 3 ). 27,33,34…”

“…Indeed, ED-XRF-MC protocol has already been applied in the analysis of metals covered by different corrosion products, such as oxides like cuprite (Cu 2 O) and tenorite (CuO), such carbonates as malachite (Cu 2 (CO 3 ) 2 (OH) 2 ) and cerussite (PbCo 3 ), sulfates like brochantite (Cu 4 SO 4 (OH) 6 ), and chlorides paratacamite (Cu 2 Cl(OH) 3 ) and atacamite (Cu 2 Cl(OH) 3 ). 27,33,34 The composition of the bulk metal shows that the selected objects from Perdigõ es were produced with almost pure Cu (higher than 96.6 wt%). Arsenic was not detected or was below the detection limit in three objects (PER-543, PER-4900, and PER-20261), while it appears to be present in quite narrow contents in the rest of the materials, with percentages ranging up to 3.0 wt%.…”

Art Casting in Portuguese 19th-Century Industrial Foundries: A Multi-Analytical Study of an Emblematic Copper-Based Alloy Monument

“…The XRF/MC protocol is a well-established non-destructive methodology that combines XRF for the spectrum acquisition and XRMC for data processing, which has proved to be fully reliable for the characterisation of both the structure and the elemental composition of each layer from a multi-layered artefact. The approach used in this paper has been described in detail [12][13][14][15], and it has already been applied successfully in the analysis of archaeological and historical metals [16][17][18].…”