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SOCIETY, METALLURGY AND INNOVATION: THE IBERIAN HYPOTHESIS

Final Report Summary - SMITH (SOCIETY, METALLURGY AND INNOVATION: THE IBERIAN HYPOTHESIS)

This project has been devoted to develop our understanding of the origins of metallurgy in Western Europe and its social impact, as a starting point to facilitate comparisons on a Eurasian scale. The project has been conducted at UCL Institute of Archaeology (UK) by M. Murillo-Barroso (the Fellow) and M. Martinón-Torres (the Scientist in charge) with collaboration of colleagues from UCL and other European institutions. Most of the analytical work has been carried out at the UCL Institute of Archaeology’s Wolfson Archaeological Science Laboratories.

The main objectives proposed were:
1. To expand previous knowledge of the specific technological conditions and processes of metal production in Iberia, as a basis for comparisons with Europe and the Near East.
2. To evaluate the social and ideological impact of metallurgy in prehistoric societies.

Evaluating these objectives requires a contextualised characterisation of metallurgical technology at the local level in its specific social and technological context. Archaeological sites. Iberia was selected as the main area of study for several reasons: on the one hand, some of the earliest dates for the inception of metallurgy come from SE Iberia (Ruiz Taboada & Montero Ruiz, 1999) although these are contested by some authors (e.g. Roberts et al., 2009) and on the other hand, preliminary observations indicate idiosyncratic metallurgical technologies and social uses of metals especially in Southern Iberia (Murillo-Barroso & Montero Ruiz, 2012) while some similarities in material culture or funerary practices were observed in NE Iberia and Southern France.

This project capitalized on unprecedented access to key archaeological materials and contexts where the whole chaine operatoire (from ore to objects) could be assessed in a comprehensive way, as the project aimed to go further on the discussion of the earliest dates on a map and was designed to study technological styles and traditions in their associated contexts as potential manifestations of knowledge transfer or exchange which would allow measuring the extent of possible influences as well as the social value of metals in each society.

In order to address the first question, samples of ore, slag, crucibles, tuyeres and metals objects have been analysed at the UCL Institute of Archaeology. A preliminary appraisal by qualitative pXRF was conducted over most of the materials totaling 752 pXRF spectra. This first approach allowed identifying different compositional groups between and within sites mainly based on their levels of Arsenic (As), Zinc (Zn) and Lead (Pb) but also due to the presence of some other elements such as Cobalt (Co) or Niquel (Ni). Following their composition, 10 ore samples were selected for further XRD analyses in order to identified mineralogical species. This information on the composition and mineral species of the ores documented in the archaeological contexts guided a geological survey devoted to characterize mining districts exhibiting these characteristics in the surroundings of the metallurgical sites. A team formed by the fellow (M. Murillo-Barroso, UCL Institute of Archaeology); the main archaeologists of some of the site studied (M.D. Camalich Massieu and D. Martinn Socas, University of La Laguna, Spain); one specialist on Iberian archaeometallurgy (I. Montero, Institute of History, CSIC) and one geologist specialist on Iberia (J.M. Nieto, University of Huelva, Spain) was coordinated to conduct the geological survey. Five mining districts were selected for a geochemical study. 150 preliminary pXRF analyses were conducted on geological samples and a series of 76 samples (29 geological and 47 archaeological) were selected for further Lead Isotope Analysis (LIA) and trace element composition by MS-ICP-MS at the SGIker laboratory of the University of the Basque Country. Results will complete some gaps on the isotopic characterization of some mining districts of the area and will allow to depict the regional use of resources and the existence of regional exchange networks. A journal paper presenting the results with an special focus on the catchment areas of raw materials is currently in preparation and will be published on Open Access in the following months. An Open Access database with all data will be also made available.

Subsequent stratified sampling was conducted. 45 samples including ore, slag, crucibles, tuyeres and metal objects were selected for further Optical Microscopy examination and SEM-EDS analysis in order to better define the smelting process. 6 non-metallurgical pottery samples were also included as a matter of comparison between technical and not technical ceramics. A series of AMS dating was also conducted to evaluate the diachronic evolution since the first metallurgical evidences and their development. Results evidenced the low control and specialization on the smelting process and the limited concern on productivity in the whole sequence maybe due to the high abundance of copper outcrops on the vicinity (with copper losses in slag up to 50%, non-equilibrium reactions and variable atmospheres). Ceramics used for metallurgy did not differ from the domestic ones.

However, significant differences were observed between SE and NE Iberia (this latter area more connected to Europe through the Pyrenees as evidenced by exchange networks) which could be related to different social values of metallurgy in the two areas: Metallurgy was developed together with other activities (e.g. textile production or cereal roasting) in domestic contexts in the SE; technical ceramics did not differ from domestic ones and little metal objects were recovered from productive sites. On the other hand, metallurgy was conducted inside rock shelters in the NE (as has also been documented in the South-eastern Alps, Dolfini, 2014: 483; cf. Bud and Tylor, 1995) and some of the crucibles had beaker decoration on their surface. While the productive contexts of SE Iberia convey a picture of communal and collaborative work in which the boundaries between different crafts are faint, productive contexts and the choice of emblematic pottery for metallurgy could suggest some secrecy or symbolic dimension on the performance and social valuation of metals in the NE. A paper with analytical results of the technological process has been submitted on Open Access and is currently under evaluation.