Prehistoric copper production in the eastern and central Alps

The eastern and central Alpine copper economy played a major role in the metal supply of central Europe during the Bronze Age and Early Iron Age. In that period, the Alpine economy changed considerably as mining and metal production transformed large parts of the landscape from agrarian and remote areas into early industrialized regions. Three of the most important copper producers have been selected for this joint research project: (1) the Schwaz/Brixlegg district in North Tyrol, Austria, (2) the Mitterberg district in Salzburg, Austria and (3) the Oberhalbstein district in Graubünden, Switzerland. In all of these mining districts Bronze Age to Early Iron Age relics of copper ore mining and/or metallurgy are widespread and the archaeological investigation of a considerable number of sites is highly advanced. The state of research represents an excellent base for a supra-regional study dealing with the dynamics of prehistoric large-scale metal production in the three key-areas and beyond. The fahlore mining district of Schwaz/Brixlegg played an important role during the Early Bronze Age, when fahlore-copper became an essential raw material for the central European copper respectively bronze market. From the late Early Bronze Age on and especially during the Middle Bronze Age, the Mitterberg district dominated the copper supply. An estimated 20,000 tons of copper were produced in this region, mainly from chalcopyrite ore (eastern Alpine copper). The Mitterberg area can be considered as a starting point for technological and economical innovations in copper production (Mitterberg-process) and the associated occupation of the eastern and central Alps by specialized communities. Fahlore mining and metallurgy in the Schwaz/Brixlegg district reached a second prime during the Late Bronze Age and Early Iron Age. In the Oberhalbstein, chalcopyrite ores were exploited from the end of the Middle Bronze Age to the Early Iron Age. Due to a different geological genesis, a geochemically distinguishable type of copper is to be expected compared with the eastern Alpine copper and the fahlore-copper. Whereas the systematic archaeological investigation of mining and smelting sites in the Oberhalbstein is just at the beginning, settlement archaeology furnished strong evidence of secondary copper metallurgy. Based on specialized (mining-)archaeological investigations, highly precise chronological data using dendrochronology, geochemical analyses and econometric evaluations, the joint project aims to carry out a comparative and diachronic study of these three important prehistoric copper mining districts. The aim is to reconstruct and to better understand the development and significance of the districts, their economic dynamics and the manifold interrelations within the network of alpine metal producers. The results will be integrated into the European context of Bronze Age and Early Iron Age metal economy.

The Alps are rich in geo-resources due to their geological setting. The project focuses on the copper production during the Bronze Age and Early Iron Age (2,200 450 BC). Three regions known for their richness in copper ore deposits have been chosen for a comparative study: 1) The Mitterberg in Salzburg, Austria (D: German Mining Museum Bochum, University of Bochum, CEZ Archaeometry Mannheim), 2) the Lower Inn Valley in North-Tyrol, Austria (A: University of Innsbruck, RC HiMAT) and 3) the Oberhalbstein in the Grisons, Switzerland (CH: University of Zürich, Archaeological Service of the Grisons). The 3 years project has been financed by the FWF, DFG and SNF. The starting point was the state of the art (2012) in mining archaeological research. Whereas the Mitterberg has a more than 100 years old tradition, systematic investigations in the Lower Inn Valley only started in the 1990ies and the Oberhalbstein was considered a few years ago as a virgin area with regard to mining archaeological research. One aim was to update the knowledge by archaeological fieldwork, especially in North-Tyrol and in the Grisons. This knowledge then should provide a basis for a comparative study with the aim to understand the dynamics in space and time in view of technological, social and economic developments in the range of copper production. At the Mitterberg a focus was directed to only little explored ore beneficiation activities which could be dated mainly into the 14th/13th century BC. In the Lower Inn Valley excavations were concentrated on a Late Bronze Age smelting site (12th/11th cent. BC) as well as on Early Iron Age mines (8th cent. BC). In the Oberhalbstein prehistoric copper production is mainly represented by smelting sites of the Early Iron Age (8th/7th cent. BC). During field prospection a mine of that period could be detected for the first time. The obtained data from the areas under investigation strongly support the primal hypothesis, that there was a chronological and East-West oriented spatial development in the domain of alpine copper production. One question was directed towards the temporal change of raw material from different ore deposits for the copper production. The different ore types in the three key-areas give an ideal basis for the discussion of technological developments and provenance studies (finished products). The geochemical fingerprint of ores in copper/bronze artefacts makes it possible to distinguish between different raw material sources: chalcopyrite dominated ores poor in trace elements from the Mitterberg, fahlore with antimony, arsenic and silver contents from the Lower Inn Valley and chalcopyrite rich in nickel from the Oberhalbstein. By analysing a series of well dated copper and bronze artefacts the raw material change during the Bronze Age becomes evident. In summary it can be pointed out that copper production in this part of the Alps started during the Early Bronze Age on the basis of fahlore, turned to chalcopyrite at the end of the Early Bronze Age with a following long lasting monopolisation till the beginning of the Late Bronze Age and finally used both raw materials in the Late Bronze Age and Early Iron Age.