Bronze Age Copper Smelting Site S1, Eisenerzer Ramsau

In 1992 archaeological investigations started at the copper smelting site S1 in the valley of the Eisenerzer Ramsau south-west of the town of Eisenerz in Styria, Austria. The site is situated in the north-western part of the Eisenerzer Alps. Being part of the geological zone of the Greywacky zone of the Eastern Alps these are very rich in various ore deposits. The copper smelting site S1 is the largest site of this type of archaeological sites which has been excavated so far in the Eastern Alps and is dated to the Bronze Age (phase C/D). So far four double furnaces, several roasting beds and two slag heaps have been documented. It is a most complex copper smelting site with several phases of rebuilding and use. Interdisciplinary research was carried out from the beginnings in 1992. Samples for geochemical analyses, botanical studies on the vegetation and pollenanalyses were taken and a geophysical survey was done to help localizing the furnaces. First slag analyses proved that sulfidic ores were smelted at this site. Now the excavation and the documentation of remaining features have to be carried out. The detailed documentation of the construction of the furnaces will be most important for further scientific enquiries. The final analyses of the stratigraphy will show the duration of use of this site and its furnaces. The origin and qualities of the building materials are to be examined and the metallurgy is to be described in more detail. Charcoal finds - remains from the smelting and roasting processes - are to be analysed by anthracological methods. As a late medieval charcoal kiln was found overlying the eastern part of the Bronze Age smelting site, charcoal from this kiln as well as from a kiln of the modern period nearby will be analysed for comparison. This will be a contribution to the history of vegetation of the area and supplement the pollenanalyses already done earlier on.

In the Eastern Alps of Austria the smelting of copper ore was widely practised in the Bronze Age. Copper sulphides as well as fahlore were used for smelting. In a valley called Eisenerzer Ramsau south west of the small mining town of Eisenerz in Styria 22 sites of prehistoric copper smelting were found. The excavation of one of the largest sites - the Copper Smelting Site S1 - started in 1992 and finished in 2006. It also proved to be the largest excavated site of its type dating to the Middle Bronze Age in the Eastern Alps. It shows the characteristic setting of Eastern Alpine copper-works consisting of at least one roasting hearth and two shaft furnaces as one unit. There were six double furnaces accompanied by the roasting hearths. In all there were uncovered ten roasting hearths, eleven furnaces and a fair number of pits varying in size and use. This vast site was used over quite a long period between the 17th and the 13th century B.C. at maximum. The copper workers repaired most furnaces several times. The chronological sequence is well documented by the stratigraphical record of three double furnaces in the western part of the site as well as by the remains of further three double furnaces and three separate slag deposits. Wood as well as charcoal supplied the energy for the metallurgical process. For the first time it was now possible to analyse the type of wood using even very small charcoal pieces. There seemed to be no special selection of the type of wood used for the smelting. Spruce, beech and fir as well as sycamore and ash were taken. The archaeological remains of roasting hearths and smelting furnaces especially qualified for the use of the archaeomagnetic dating method. The paleomagnetic directions support the stratigraphical sequence and largely confirm it. Moreover, these are the first dates of the Middle Bronze Age in Central Europe and provide a valuable informative basis for the gradient of the secular variation curve in this period. In the Late Medieval Period the eastern edge of the Bronze Age site was used for setting up a charcoal production site. A large pit, 1 meter deep, 4 m wide, was dug and used for burning charcoal. This is the first archaeological evidence for charcoal burning in the Medieval Period in the Eastern Alps. Spruce was charred beside beech, fir and sycamore. Thin pieces of beech were used for setting the fire. Spruce was again the main wood to be used in another type of charcoal kiln - a rectangular structure called "long kiln" or "laying kiln" - dating to the Early Modern Period. The botanical (anthracological) analyses clearly show a continuous decline of fir since the Bronze Age and at the same time a frequency in occurrence of spruce in the forest of the area.