Late Bronze Age hoard studied by PIXE

Abstract

The hoards of metallic objects belonging to the Late European Bronze Age can be interpreted differently depending on the type, number and composition of the artefacts. PIXE analysis has been performed in nine items from the Hoard of Freixanda in Portugal comprising 4 socket axes, a palstave axe, a ring, a chisel, a dagger, and a casting debris. Besides the composition of the main matrix elements, that is Cu and Sn, the amount of trace elements of interest like, As, Pb, Ni and Ag has been determined using this ion beam technique. The high tin content alloy and the high purity of the metals from the Freixanda hoard are characteristic of the Portuguese and Spanish Late Bronze Age metallurgy, supporting the idea of a regional production.

New insights on Late Bronze Age Cu-metallurgy from Coles de Samuel hoard (Central Portugal): A combined multi-analytical approach

“…4). This result points out a different operational sequence with respect to other one single-looped palstaves from Central Portugal: in fact, the palstaves from Freixanda (Gutiérrez Neira et al, 2011;Vilaça et al, 2012b), Casais das Pedreiras (Bottaini et al, 2012), and Porto do Concelho (Bottaini, 2013) show a microstructure suggesting that objects were finished with one or more cycles of forging and annealing. This kind of treatment would make the cutting edge harder and thermo-mechanically more appropriate to withstand stronger impacts.…”

“…With respect to typology, Coles de Samuel hoard reproduces a common pattern as regards the combination between specific kinds of objects: for instances, socketed axes and palstaves have been found in association in the hoards from Cabeço de Maria de Candal (Bottaini, 2013;Gutiérrez Neira et al, 2011;Vilaça et al, 2012b) and Casais da Pedreira (Bottaini, 2013;Bottaini et al, 2012); palstaves and sickles are known in the hoards of Travasso (Leitão and Lopes, 1985), Porto do Concelho (Jalhay, 1944;Bottaini, 2013;Bottaini et al, 2015) and Moura da Serra (Coffyn, 1985); a socketed axe was associated with bracelet-shaped objects in the Casal dos Fiéis de Deus hoard (Vasconcelos, 1919-20;Melo, 2000), etc.…”

“…In fact, notwithstanding the caution that should be applied when comparing quantitative chemical results obtained with different analytical techniques and methodologies, the sporadic presence of Pb detected in the Coles de Samuel collection is characteristic of a number of hoards and habitats from the region (Bottaini, 2013;Bottaini et al, 2012;Figueiredo et al, 2010;Figueiredo et al, 2013;Gutiérrez Neira et al, 2011;Valério et al, 2006;Valério et al, 2007;Valério et al, 2010;Vilaça, 1997).…”

“…However, four specimens from the hoard of Freixianda (Gutiérrez Neira et al, 2011;Vilaça et al, 2012b) and one from Moinho do Raposo (Bottaini, 2013) have been recently studied. With the exception of one fractured and incomplete socketed axe from Freixianda, which presents a dendritic as-cast microstructure, the remaining ones are characterised by the occurrence of deformed equiaxial grains with annealing twins and slip bands evidencing the application of thermomechanical treatments.…”

Combining X-ray based methods to study the protohistoric bronze technology in Western Iberia

“…Analytical studies concerning the metallurgy in Western Iberia during the Late Bronze Age (LBA, 1200-800 BC) show that artefacts are composed of Cu-Sn alloys with low impurity patterns [5,10,12,28]. Local metallurgical remains indicate the production of such alloys by smelting metalliferous ores in ceramic crucibles [10,28].…”