Early metal mining in the middle Lahn valley
The middle Lahn valley lies at the intersection of the Westerwald, Taunus, Vogelsberg and Wetterau. Rich ore-bearing hills appear here, and the project focuses on the pre-industrial exploitation and subsequent processing of these resources. In tandem with this, geochemical studies have been carried out on the ore deposits and slags. The aim is to gain an overview of the historical mining sites and their relationship to the contemporaneous settlements. Another aim is to undertake an assessment of pre-modern metal extraction.
Prior to this project, nobody knew when humans had begun to exploit the deposits of red haematite and pyrolusite in the eastern part of the Rhenish Massif (Rheinisches Schiefergebirge). There were signs of historical or even prehistoric iron extraction, but it was only the work done in this project that allowed precise identification of the age of these mines: iron production took place during the Iron Age, the Roman Iron Age and the early Middle Ages. We were able to examine some of these find sites more closely.
The smelting remains in Wetzlar-Dutenhofen and a forge site situated only 1.5 km away in Lahnau-Atzbach go back to the 5th century BC. This makes them the oldest places of iron extraction in Hesse. Iron was also produced in the Roman Iron Age in Wetzlar-Nauheim, or at least there are signs of local production from the late 1st century AD onwards. In Wetzlar-Dalheim we were able to record numerous ore deposits and slag sites on the northern bank of the Lahn. They lay directly below one of the newly discovered deposits of brown haematite. Over a 300 m long and 50-100 m wide strip, geomagnetics (Posselt & Zickgraf Prospektionen GbR) was used to gain a preliminary insight into the structure of the site. The image obtained in this way shows distinct roundish anomalies, partly arranged in rows. In conjunction with surface finds, these can be assumed to be the sites of ovens or hearths; large rectangular anomalies in the centre of the area may have been pit houses. Overall, the area displays a high concentration of finds, with surface pottery finds giving clear indications of multi-period usage including prehistory, the Roman Iron Age, and the early to high Middle Ages. 14C data from drill prospecting confirm the dating of the ceramics, proving that there was an iron production district here, continuously or with interruptions, from the Roman Iron Age to the Carolingian period – unlike the area to the east of the Rhine. It may even have been the Germanic tribes who set the course for the later metal industry.
Our subsequent site prospecting initially concentrated on sub-sections, particularly of the red haematite district to the north and south of the Lahn, and later focused on the central brown haematite deposits. Two important findings should be noted here: in the core areas of the ore deposits, particularly in the hilly hinterland on both sides of the Lahn, modern opencast mining had largely destroyed older traces of mining and smelting. The smelting sites that have been preserved mainly consist of large slag heaps. The slags show distinct flow structures, which must have come about in an advanced process involving smelting furnaces. After numerous comparisons with other regions, this smelting debris can be dated to the high and late Middle Ages. We were able to locate and partially prospect some well-preserved mining complexes north of the Lahn in Wetzlar-Blasbach, on the northern slopes of the Bleidenberg, and on the eastern side of the Dünsberg. To the south of the Lahn we discovered a sinkhole area, several slag heaps and bench terraces near Ebersgöns. Our prospecting also showed that – particularly in the forested areas of the hinterland – outstanding mining complexes may have been preserved, dating back to a time when extraction and smelting still happened in the same place, that is, the medieval phase of use. Near Solms-Burgsolms we discovered slags pointing to an early type of smelting furnace which may belong to the Iron Age.
The last site we examined was a complex from the early or high Middle Ages, consisting of a smelting site and surrounding charcoal burning sites, in Blasbach, in the administrative area of Pfaffenmark. This site, very typical of its kind, is characterized by a distinct roundish slag heap, about 10 m high, with fluid slag, a small flattened area on the uphill side, and a detached collection of stones to the southeast (presumed to be the furnace site). Thanks to its obvious one-phase nature and its good, undisturbed state of preservation, this metallurgical complex is of great importance for the (early) medieval phase of extraction.
Prof. Dr. Andreas Schäfer / Universität Bamberg
Kommission für Archäologische Landesforschung Hessen (KAL)
Deutsches Bergbau-Museum Bochum
Philipps-Universität Marburg, Vorgeschichtliches Seminar / Andreas Schäfer
Institut der KAL, Wiesbaden, Archäobotanische Abteilung
Fa. ARGUS, Tübingen / Guntram Gassmann
- A. Schäfer, N. Buthmann, B. Zickgraf, Wetzlar-Dalheim vor Buderus. Zu den Anfängen der Eisengewinnung im Lahntal. Hessen-Archäologie 2001, 120-123.
- A. Schäfer, Th. Stöllner, Frühe Metallgewinnung im Mittleren Lahntal. Vorbericht über die Forschungen der Jahre 1999-2001. 6. Berichtsheft der KAL, 2000/2001, 83-111.
- A. Schäfer, Th. Stöllner,Schmiedewerkstatt von Lahnau-Atzbach. Katalogbeitrag in: H. Baitinger (Hrsg.), Glaube – Mythos – Wirklichkeit. das Rätsel der Kelten vom Glauberg. Katalog zur Ausstellung Frankfurt 2002 (Stuttgart 2002) 269 f.