Innovations in iron smelting—geoarchaeological and archaeometallurgical investigations on four sites in the Germania magna

Abstract This study compares four iron smelting sites in the northern Harz foothills, intensively used during the early Roman Imperial period. A key feature is the use of oxidized clay ironstone geodes (OCISC), an ore previously unknown in the archaeological record of Germania magna/Barbaricum, confirmed as the source material at three sites. Geochemical analyses (WDXRF) of the ores are compared with published and unpublished slag data from the same locations. Evidence suggests that furnace shafts were reused multiple times, likely to increase efficiency. The sites also show similar spatial patterns in their topographical settings and distances to water sources and ore outcrops. Finally, the study considers how this technological innovation reached a region where earlier evidence for independent iron smelting is scarce.