Bell beaker copper use in central Europe: a distinctive tradition? A re-evaluation of the composition of copper artefacts and its effects on the properties of the metal
Merkl, Matthias Bernd
This thesis is concerned with the manufacture of copper artefacts by the users of Bell Beaker pottery in the Eastern Bell Beaker group in central Europe, and addresses the question: did these metalworkers have distinct metallurgical abilities, techniques and preferences that set them apart from contemporary and earlier metal-using groups in the same region? Can we talk of a 'Bell Beaker' metallurgical tradition? Despite the long history of research into the so-called Bell Beaker phenomenon, there has been no definite answer to this question. The composition of copper artefacts is influenced by the production process and the composition of the ore, and so two artefacts that share a similar composition reflect a metallurgical similarity. Artefact composition is defined by variations in trace element impurities that are contained in the copper. Trace elements, however, do not only point to metallurgical processes: they also affect the physical and chemical properties of the metal. Consequently, this thesis aims to clarify whether the distribution of the Bell Beaker phenomenon throughout central Europe and its dissociation from other archaeologically visible groups there is associated with the use of a specific metallurgical tradition. It will be argued that if metal workers of other archaeological groups of the 3rd millennium BC, such as the Corded Ware complex, dealt with different types of copper, having different properties, this would give an insight into the relationship between those people and the Bell Beaker phenomenon in central Europe. In order to explore these issues, a database of some 1943 trace element analyses of Chalcolithic copper objects from central Europe has been created, then statistically grouped and evaluated according to two questions: firstly, were metalworkers selecting specific types of copper for their physical and chemical properties? Secondly, are Eastern Bell Beaker copper artefacts made from specific types of copper? The result of the statistical evaluation has demonstrated that, generally, copper artefacts with higher impurity levels are more common throughout the 3rd millennium BC than in earlier periods. In particular, higher concentrations of arsenic, antimony, lead and nickel (> c. 2%) indicate that these types of copper have improved properties (e.g. hardness, tensile strength, malleability). Furthermore, with the appearance of archaeological remains classified as belonging to the Earliest Bronze Age (e.g. the Blechkreis and the Nitra group), there is an almost exclusive use of types of copper that contain even greater quantities of antimony, nickel and arsenic. These types of copper may have been preferred by metalworkers because their superior tensile strength and hardness improves the quality an artefact. It therefore appears that the metallurgical properties of copper were gradually improved throughout the Chalcolithic in central Europe. It seems that there was a network distributing copper over the area of this research, because the types of copper used by the Eastern Bell Beaker group do not show great regional variation. The uniformity of the archaeological records of the Eastern Bell Beaker group is also reflected in their metalworking tradition. However, it was for the first possible to clarify that the people of the Eastern Bell Beaker group did not deal with a specific type of copper compared with other archaeological groups. Bell Beaker copper types do not differ from those generally used throughout the 3rd millennium BC, albeit that only a small set of Bell Beaker artefacts (chiefly daggers and awls) has provided trace element analyses. As neither regional nor cultural specific metallurgy can be detected for this period, it is argued that the Eastern Bell Beaker group is – at least in metallurgical terms – connected with other local communities in central Europe. Consequently, metallurgy cannot be cited as a defining factor of archaeological groups in central Europe during the 3rd millennium BC. In terms of the Corded Ware and Bell Beaker groups, metallurgical expertise was probably at the same level of knowledge. Hence, even if the types of copper artefact that were manufactured were ‘culture-specific’, the manufacturing techniques and the access to resources were not restricted to a single archaeological group. It can therefore cautiously be suggested that, between c. 2700 and 2000 BC, metallurgists – perhaps as itinerant craftsmen – produced copper artefacts according to the demands of their ‘customers’.