EDXRF and micro-EDXRF studies of Late Bronze Age metallurgical productions from Canedotes (Portugal (original) (raw)
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This paper focuses on the study of a group of metal artefacts recently recovered during the archaeological excavations in Vila do Touro (Central Portugal), i.e., 19 artefacts and a small metallic inclusion embedded in a pottery sherd. The objects have been analysed by an X-Ray Fluorescence spectrometer to characterise the elemental composition of metal artefacts. A Scanning Electron Microscope with X-ray Microanalysis System and an optical microscope were used to observe and chemically characterise the metal inclusion in the pottery. The fragment of an ingot was also analysed by a multicollector Inductively coupled plasma mass spectrometer to address issues bound to the provenance of raw material. The results revealed different compositional patterns (pure copper, binary bronze, i.e., Cu+Sn, leaded bronzes, i.e., Cu+Sn+Pb, and gold), while pointing out the Ossa Morena region (Southwest of the Iberian Peninsula) as likely source of copper used to produce the ingot.
Munibe Antropologia-Arkeologia
This paper focuses on the study of a group of metal artefacts recently recovered during the archaeological excavations in Vila do Touro (Central Portugal), i.e., 19 artefacts and a small metallic inclusion embedded in a pottery sherd. The objects have been analysed by an X-Ray Fluorescence spectrometer to characterise the elemental composition of metal artefacts. A Scanning Electron Microscope with X-ray Microanalysis System and an optical microscope were used to observe and chemically characterise the metal inclusion in the pottery. The fragment of an ingot was also analysed by a multicollector Inductively coupled plasma mass spectrometer to address issues bound to the provenance of raw material. The results revealed different compositional patterns (pure copper, binary bronze, i.e., Cu+Sn, leaded bronzes, i.e., Cu+Sn+Pb, and gold), while pointing out the Ossa Morena region (Southwest of the Iberian Peninsula) as likely source of copper used to produce the ingot.
Journal of Archaeological Science: Reports, 2016
The hoard from Coles de Samuel is one of the largest Cu-based metal collections from the Late Bronze Age (LBA) (13th-8th centuries BC) ever found in Central Portugal, consisting of 18 artefacts which typologically display a strong regional identity. In the present study, an integrated multi-analytical approach combining Energy Dispersive X-Ray Fluorescence (EDXRF) analysis, Optical Microscopy (OM) and Scanning Electron Microscopy with Energy Dispersive X-ray spectroscopy (SEM-EDS) has been used to characterise the artefacts both from a chemical and microstructural point of view with the aim to unravel their elemental composition and technological features. Results show that all artefacts are made of binary bronze (Cu-Sn) alloys, with a Sn content in the range of 8.7 ± 0.9 and 13.0 ± 1.0 wt%, with minor elements (Pb, As and Fe) never exceeding 1.1 wt% in total. The microstructure of the vast majority of the metal objects (13 out of 18) shows the presence of equiaxial α-copper grains with annealing twins and slip bands suggesting that, in the manufacturing process, they were subjected to forging plus annealing cycles. The remains of the objects present an as-cast microstructure constituted by dendritic structures, suggesting that metals did not suffer any thermo-mechanical operation after being removed from the mould. Pb, Ag and Au-rich globules together with Cu-S and unalloyed Cu-inclusions have been observed as well, resulting from impurities from ores. The typological characterisation of these metals and their archaeometallurgical data are consistent with an indigenous LBA Iberian metallurgical production supporting the hypothesis of a regional/local production and use of the artefacts from Coles de Samuel.
Journal of Archaeological Science, 2010
A collection of 54 bronze artefacts recovered from the inland settlement of Castro dos Ratinhos (Portugal) and belonging mainly to the 9th-8th centuries BC, was studied by the use of non-invasive and micro analytical techniques. EDXRF, Micro-EDXRF, SEM-EDS and Optical Microscopy were used to determine the alloy composition and to identify the different thermo mechanical operations applied in the production of the artefacts. Results show that the collection is entirely composed of good quality binary bronzes (with an average tin content of 10.1 AE 2.5%). Alloys with higher tin contents were kept in as-cast condition and used in the making of ornaments, while tools were often finished with forging and annealing operations. Despite the existence of some Orientalising features in the Castro dos Ratinhos, e.g. rectangular habitat structures, wheel-turned ware and amphorae, the exclusive use of binary alloys with a narrow range of tin content seems to be associated with an indigenous metallurgical tradition inherited from the Late Bronze Age. This may indicate that the Phoenician interaction within the inland indigenous communities was a slow and selective process, probably dependant on the social-economic and cultural development of local communities.
Middle Bronze Age Arsenical Copper Alloys in Southern Portugal
Archaeometry, 2015
In the Iberian Peninsula, the copper metallurgy from the Chalcolithic to the Middle Bronze Age (MBA) was mostly characterized by low arsenic contents. A collection of 53 MBA artefacts from southern Portugal was analysed by micro-EDXRF, optical microscopy, SEM-EDS and Vickers to investigate the metal composition and manufacture. No technological distinction was found between artefacts from domestic and funerary contexts, which were radiocarbon-dated to 2000-1500 cal BC. The arsenic contents of almost 100 MBA artefacts from this region, including the above-mentioned set, have a Gaussian distribution with a high average (3.9 wt% As). Possible explanations are discussed for this distinctive metallurgy at the southwestern end of the Iberian Peninsula.
Heritage, weathering …, 2006
atice metal was recognized as a new material in prehistorical times metallic artifacts began to be made and the metallurgical skills started to develop. Metallurgical scraps found in archaeological sites normally evidence metallurgical production of artifacts in situo Studies of metal scraps can reveal the different stages ofthenno-mechanical treatments that the artifacts were subjected to in arder to obtain a selected shape and hardness. While for metal artifacts sample taking can be problematic, sample taking in metallurgical scraps can be easier since scraps have nonnally no artistic/esthetical display value. Additionally, corrosion phenomena can be evaluated in scraps that frequently have not been subjected to any conservation treatment. This paper deals with metallographic (optical and electron microscopy), EDS-SEM and EDXRF studies that have been undertaken in correr based metallurgical bars of circular and square sections from Santa Luzia site, in central Portugal.
A large ceramic vessel was discovered at São Brás (southern Portugal) containing a metallic hoard from the Chalcolithic/Early Bronze Age period. These weapons and tools were characterized by microanalytical techniques as being composed of copper with varying arsenic contents (2.2 ± 1.6 wt%) and minor amounts of lead, bismuth and iron. The collection shows a clear association between daggers and copper with a higher arsenic content, which can be explained by the high status of these silvery alloys. Finally, the compositional distribution of the hoard was compared with the metallurgy of the Bell Beaker and non–Bell Beaker communities inhabiting the southwestern Iberian Peninsula.
Micro-EDXRF study of Chalcolithic copper-based artefacts from Southern Portugal
X-Ray Spectrometry, 2015
A collection of 39 metallic artefacts recovered in archaeological sites of Southern Portugal was studied by micro-EDXRF to identify their compositions and the use of metal among ancient communities. Artefacts presented different typologies such as tools (e.g. awls, chisels and a saw) and weapons (e.g. daggers and arrowheads) mostly belonging to 2500-2000 BC. The results show copper with variable amounts of As and very low content of other impurities, such as Fe, Pb or Sb. Moreover, nearly half of the collection is composed by arsenical copper alloys, and an association was found between arsenic content and typology because the weapons group (mostly daggers) present higher values than tools (mostly awls). These results suggest some criteria in the selection of arsenic-rich copper ores or smelting products. Finally, the compositions were compared to those of other collections from neighbouring regions and different chronology to determine metallurgical parallels.