The Construction of the Bronze Age Copper-Works in the Alps

In the Eastern Alps the smelting of copper ore was widely practised in the Bronze Age. Copper sulphides as well as fahlore were used for smelting. The aim of the project is to supplement and refine the model of the Eastern Alpine copper-works of the Bronze Age established by C. Eibner in 1982 on the basis of the excavation results of the Copper Smelting Site S1 and other, more recently published reports on copper smelting sites in the Alps. The archaeological excavation at the Middle Bronze Age Copper Smelting Site S1, in the valley called Eisenerzer Ramsau in Styria, carried out in 1992-2006, proved to be the largest and most complex site of its type and period in the Eastern Alps and shows the characteristic layout of Eastern Alpine copper-works, consisting of at least one roasting hearth and two shaft furnaces as one unit, supplemented by a distinctive slag dump. The main features are the remains of six double furnaces, ten roasting hearths, a number of pits of variable size and form, and three separate slag dumps. The presentation of the new model is based on the archaeological excavation results from the Copper Smelting Site S1 which will be presented by detailed and general plans, photographs and detailed descriptions, thus establishing a basis for the reconstruction, as well as for metallurgical analyses and experiments and a discussion on possible technological development. Another emphasis of the project is on establishing a temporal sequence and possible synchronism of the various structures. This is based on archaeological methods such as stratigraphic excavation and archaeological dating of small finds as well as on the comparison of these results with dates achieved by absolute dating methods. The activities on site have already been dated to 17th - 13th century BC which now needs to be confirmed or even differentiated by a further number of radiocarbon dates. As the archaeological remains of the pyrotechnical activities on a site of this type are especially suitable for the application of the archaeomagnetic dating method, the Copper Smelting Site S1 has been used as an experimental field for further research on this special dating method from the start of excavation. The samples measured from the site will ultimately result in part of the secular variation curve for Austria for the Bronze Age being established and can already be used to verify the stratigraphical sequence in cases where the sequence of archaeological layers is uncertain. Archaeometallurgical analyses will describe the metallurgical process in all detail; a futher aim is the description of apossible technological development within the Middle Bronze Age. The question of fuel (wood, charcoal, type of wood used) has already been pursued by anthracological analyses of all charcoals found at the site. These analyses will now be interpreted in detail on the basis of the stratigraphic evidence. These analyses also provide important data for a description of the local vegetation history. The diet of the copper workers can only be inferred from a number of very small burnt animal bones in the absence of any other remains such as grains, fruit or vegetables being found.

The presentation of the archaeological excavation from the Bronze Age Copper Smelting Site S1 in the Eisenerzer Ramsau Valley, Styria, and the interdisciplinary research on the materials in a monograph now allows the reconstruction of the Bronze Age copper-works in the Eastern Alps. The main features of these copper smelting sites are a roasting hearth a rectangular, shallow pit lined with vertically set stones , and two shaft furnaces (double or twin furnaces) built into the slope as well as a slag dump. This detailed knowledge of the construction of these sites is a necessary base for the understanding of the workings at copper smelting sites and therefore most important for any future experiments regarding the smelting process.The Middle Bronze Age Copper Smelting Site S1 (19922006) is the largest site as well as the best analysed site of this type in the Eastern Alps which has been excavated so far. Six of originally eight double furnaces, ten roasting hearths and three slag dumps as well as several pits of variable size, form and function were recorded. In general, the activities at the site date to the 1611. century BC, though the main phase of use dates to the 15.13. century BC.A multi-step process is suggested by the extensive archaeometallurgical analyses of the waste of the smelting process slags and debris from the smelting furnaces. First the ore, chalcopyrite, was roasted in the roasting hearth. Then matte was produced in the furnace. It is assumed, that the matte was repeatedly roasted with new ore and further enriched in copper to produce metallic copper. Two small raw copper fragments of eastern alpine copper indicate this hypothesis. However, there is no indication of any further processing (refining) at the site itself. This well-developed archaeometallurgical process can be referred to as a high-tech production in the Middle Bronze Age. A somehow more efficient smelting process is noted in the material from the youngest furnaces at the site, dating to the beginning of the Late Bronze Age.As energy source fresh wood was used for roasting the ore and quite possibly also for smelting in the shaft furnaces. Botanical (anthracological) analyses of the charcoals confirm the use of beech, spruce/larch and fir as well as maple, ash and others. The charcoal rich layers in the furnaces, in front of the furnaces and on the slag dumps also revealed a small amount of burnt animal bones. These tiny fragments, mainly of domestic pig and sheep or goat, do not allow the reconstruction of the smelters diet as they come from parts with little meat on them. There exists no similar evidence from other smelting sites but from typical ritual sites in the Alps (Brandopferplätze). Therefore, we may assume that the burnt animal bones may be evidence for ritual actions in connection with the metallurgical process.