Abstract:Chalcolithic gold artefacts assigned to the Bell Beaker Culture in Portuguese Estremadura were analysed by micro-energy dispersive X-ray fluorescence spectrometry. These high-status jewels comprise beads of tubular, spiral and double-conical type, a spiral ring and a wire fragment. The collection is mainly composed of gold with 8.7-16.3 wt% Ag and <0.04 wt% Cu. Additionally, there is a typologically uncommon double-conical bead showing a lower Ag content (6.7 wt%). The relative intensity of the Ag-Kα and Ag-Lα… Show more
“…In the southwestern region, Chalcolithic gold replicates this compositional range (0.7–21% Ag and <0.34% Cu, see Fig. 12, Hartmann, 1982; Gonçalves, 2005; Perea et al, 2010; Nocete et al, 2014; Soares et al, 2014; Murillo-Barroso et al, 2015; Valério et al, 2017). Therefore, the higher amount of silver and copper in MB1-2 and QC5 jewelry indicates the production of artificial alloys.…”
Section: Discussionmentioning
confidence: 70%
“…1). Figure 12.Elemental composition of jewelry from Monte do Bolor 1-2 and Quinta do Castelo 5 (unfilled symbols: pendants; filled symbols: beads), 8th century BC gold buttons from a single workshop (Soares et al, 2010) and Chalcolithic gold in southwestern Iberia (after Hartmann, 1982; Gonçalves, 2005; Perea et al, 2010; Nocete et al, 2014; Soares et al, 2014; Murillo-Barroso et al, 2015; Valério et al, 2017). …”
Section: Discussionmentioning
confidence: 99%
“…The surface enrichment phenomena of archaeological gold originates from the surface depletion of the less noble elements; however, a passivation process in high gold content alloys (over 50%) results in the alteration of only a few atomic layers at the alloy surface (Rapson, 1996). Therefore, the effective penetration depth of characteristic X-rays (Cu-K α , Au-L α , and Ag-K α , c. 10 − 60 µ m, Valério et al, 2017) allows a suitable determination of the composition of such gold alloys despite using a noninvasive methodology, an essential feature to study ancient gold jewelry.…”
The gold technology in Iberia underwent an important development during the Early Iron Age (EIA) following the arrival of new technological skills from the Mediterranean region, including the use of filigree, granulation, and brazing. This work presents the microanalytical study of EIA gold jewels (22 spherical beads and four tongue pendants) recovered from three graves in southern Portugal. The set of jewelry, showing an extraordinary stylistic resemblance, was characterized by optical microscopy, micro energy-dispersive X-ray spectrometry and scanning electron microscopy with X-ray microanalysis to establish the alloy composition and production techniques. The pieces show a close technological relation, making use of artificial gold alloys with different amounts of silver (c. 40 and 25%). The decorative styles include different types of filigree (solid wires and hollow wires), while the joining techniques comprise brazing with Au-Ag-Cu solders and, probably, sintering. In spite of those technological and stylistic features, clearly pointing to a Mediterranean influence, the absence of granulation suggests an indigenous workshop where exogenous technologies/decorations were not yet fully integrated in the manufacture of such luxury items.
“…In the southwestern region, Chalcolithic gold replicates this compositional range (0.7–21% Ag and <0.34% Cu, see Fig. 12, Hartmann, 1982; Gonçalves, 2005; Perea et al, 2010; Nocete et al, 2014; Soares et al, 2014; Murillo-Barroso et al, 2015; Valério et al, 2017). Therefore, the higher amount of silver and copper in MB1-2 and QC5 jewelry indicates the production of artificial alloys.…”
Section: Discussionmentioning
confidence: 70%
“…1). Figure 12.Elemental composition of jewelry from Monte do Bolor 1-2 and Quinta do Castelo 5 (unfilled symbols: pendants; filled symbols: beads), 8th century BC gold buttons from a single workshop (Soares et al, 2010) and Chalcolithic gold in southwestern Iberia (after Hartmann, 1982; Gonçalves, 2005; Perea et al, 2010; Nocete et al, 2014; Soares et al, 2014; Murillo-Barroso et al, 2015; Valério et al, 2017). …”
Section: Discussionmentioning
confidence: 99%
“…The surface enrichment phenomena of archaeological gold originates from the surface depletion of the less noble elements; however, a passivation process in high gold content alloys (over 50%) results in the alteration of only a few atomic layers at the alloy surface (Rapson, 1996). Therefore, the effective penetration depth of characteristic X-rays (Cu-K α , Au-L α , and Ag-K α , c. 10 − 60 µ m, Valério et al, 2017) allows a suitable determination of the composition of such gold alloys despite using a noninvasive methodology, an essential feature to study ancient gold jewelry.…”
The gold technology in Iberia underwent an important development during the Early Iron Age (EIA) following the arrival of new technological skills from the Mediterranean region, including the use of filigree, granulation, and brazing. This work presents the microanalytical study of EIA gold jewels (22 spherical beads and four tongue pendants) recovered from three graves in southern Portugal. The set of jewelry, showing an extraordinary stylistic resemblance, was characterized by optical microscopy, micro energy-dispersive X-ray spectrometry and scanning electron microscopy with X-ray microanalysis to establish the alloy composition and production techniques. The pieces show a close technological relation, making use of artificial gold alloys with different amounts of silver (c. 40 and 25%). The decorative styles include different types of filigree (solid wires and hollow wires), while the joining techniques comprise brazing with Au-Ag-Cu solders and, probably, sintering. In spite of those technological and stylistic features, clearly pointing to a Mediterranean influence, the absence of granulation suggests an indigenous workshop where exogenous technologies/decorations were not yet fully integrated in the manufacture of such luxury items.
“…Besides, the effective probe depth of analysis in any of the used X-ray spectroscopy techniques is not only dependent on the energy of the exciting source (electrons, X-rays or protons) but especially on the energy of the characteristic X-rays (transition) emitted by the sample elemental constituents. Therefore, due to the energy differences of the emitted X-rays, the Au-M lines or Ag-L lines provide information from a much shallower surface sample layer than the Au-L and Ag-K lines (Valério et al 2017). Our results, both for EDXRF and Micro-PIXE, were obtained considering the measured Au-L and Ag-K lines intensity.…”
Section: Hemos Empleado Fluorescencia De Rayos X Por Energía Dispersimentioning
We have used EDXRF, Micro-PIXE and optical microscopy (metallographic analysis), complemented with SEM-EDS, to first determine the elemental content, and second, to identify the process used to join the components (disk, peripheral rod and tab) of several Iron Age gold buttons. These have a very similar typology and were found at three archaeological sites in the South-Western part of the Iberian Peninsula. A set of 35 buttons from Castro dos Ratinhos (7), Outeiro da Cabeça (23) and Fortios (5) were analyzed and the results published in Trabajos de Prehistoria (Soares et al. 2010). Recently Perea et al. (2016) have published analyses of other 4 gold buttons from Fortios with the same purpose, but only using one technique, SEM-EDS. As they only analysed the rough surface layer, the results are neither effective nor reliable, taking into account the constraints associated with the technique, namely the small depth reached (< 2 µm) by the incident beam and, consequently, its sensitivity to the topography of the analyzed surface. Despite these constraints, they have accepted uncritically their results and, at the same time, question our own analyses and results and the interpretation we have made. Here we discuss the approach of Perea et al. in order to determine not only the elemental content of the Fortios gold buttons, but also to identify the joining process used in their manufacture.
RESUMEN
“…Os valores médios das diversas análises efectuadas encontram-se na Tabela 1. Trata-se, por conseguinte, de uma espada manufacturada em cobre arsenical, enquanto que a folha de ouro que recobre os terminais dos rebites é feita de uma liga natural de ouro e prata, tendo em conta o seu teor de cobre (<1 %) (ver, por exemplo, Valério et al, 2017). A associação desta liga a um grande artefacto de cobre arsenical indicia uma antiguidade para esta técnica de douramento, para a qual ainda não existiam ligas artificiais de ouro e prata, como será discutido mais adiante.…”
In this paper, we present a detailed examination of a sword dating from the Southwestern Middle Bronze Age, which was found several years ago during farming activities near the town of Serpa, Portugal. The sword was apparently found out of an archaeological context. The finder of the sword, who kindly allowed us to study it, cleaned the artefact of its corrosion and kept it in good conditions. The sword is about 50 cm long and its handle show two rivets (another one is missing) which are kept housed in notches. The rivets’ heads are spherical caps covered with a golden leaf. The use of a p-EDXRF equipment allowed us to determine and quantify the elemental composition of the blade, as well as of the golden leaf covering the rivet heads. It was thus possible to establish that the blade was manufactured with arsenical copper, while the composition of the golden leaf refers to a natural alloy. Finally, the Monte das Oliveiras sword is compared with several other coeval examples of Southern Iberia weaponry. Its hilt design, namely the three peripheral notches, seems to be of an unique variant in swords, being relatively rare in similarly shaped weapons, such as daggers.
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