Metallographic studies of copper based scraps from the Late Bronze Age Santa Luzia archaeological site (Viseu, 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.
Archaeological and Anthropological Sciences
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METALLOGRAPHIC AND CORROSION RESEARCH OF COPPER FROM ARCHAEOLOGICAL SITES
METALURGIJA, 2015
In this study, copper slabs - ingots, from both Gdańsk and Kraków were examined. Besides metallographic examinations, attention was focused on analyses of corrosion products. The following techniques were applied: scanning electron microscopy with fluorescent X-ray microanalysis and X-ray diffraction. The conducted investigations enabled determination of the causes of corrosion in the old copper slabs, due mainly to the mediaeval alloying techniques and copper processing technologies. Keywords: copper, corrosion, archaeometallurgy, microstructure
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.
EDXRF and micro-EDXRF studies of Late Bronze Age metallurgical productions from Canedotes (Portugal
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2007
Metallurgical production in Central Portugal during the Late Bronze Age was primarily based on copper-tin alloys, despite influences from the Atlantic area where copper-tin-lead alloys are common. Metallic artefacts from archaeological site of Canedotes (Central Portugal) were analysed by EDXRF to establish the type of alloys present. Polished spots in selected artefacts were also analysed by micro-EDXRF to determine the major and minor elemental composition of the original alloys. The collection constitutes 18 copper-tin artefacts and one unalloyed copper artefact with tin and arsenic as minor constituents. Artefacts that require a thermomechanical finishing process, such as tools and weapons, seem to have improved control over the tin content. The composition of two buttons, one cramp and one metallic droplet suggest that some of the copper sources were rich in arsenic. Finally, the low iron content of the artefacts seems to agree well with the smelting of copper ores in crucible furnaces, a smelting process used in certain areas of the Iberian Peninsula until pre-Roman times.
In this study, copper slabs -ingots, from both Gdańsk and Kraków were examined. Besides metallographic examinations, attention was focused on analyses of corrosion products. The following techniques were applied: scanning electron microscopy with fluorescent X-ray microanalysis and X-ray diffraction. The conducted investigations enabled determination of the causes of corrosion in the old copper slabs, due mainly to the mediaeval alloying techniques and copper processing technologies.
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.
Composition and microstructure of Roman metallic artefacts of Southwestern Iberian Peninsula
The Roman invasion introduces new alloys and metallurgical practices in Iberian Peninsula. The southwestern end of this region has many evidences of connections with the Roman World, but there are no studies about the manufacture and use of copper-based artefacts during this period. Therefore, a set of about 20 ornaments, tools and small attachments recovered at the Roman sites of Monte Molia˜o and Cidade das Rosas was studied by an analytical approach combining micro-EDXRF, optical microscopy, SEM–EDS and Vickers microhardness testing. The artefact composition shows a good correlation with function, namely pure copper for nails and rivets, lowtin bronze (2–6 wt% Sn) for basic tools, high-tin bronze (14 wt% Sn) for fibulae and high-lead bronze (19 wt% Pb) for a decorated jug handle. The manufacture also depends on function because most artefacts were subjected to thermomechanical processing, except the ornaments that would not benefit from post-casting work. Brass and gunmetal were only present in the site with a later chronology. A metallurgy visibly ruled by economical, aesthetical and technological concerns reinforces the evidences about the total integration of Southwestern Iberian Peninsula in the Roman World, but further studies will be essential to determine the evolution of copper-based alloys in Lusitania under Roman influence.