Observations Suggesting the Use of Manganese-Rich Oxidized Clay Iron Stone Concretions for Iron Production During the Early Roman Imperial Period in the Inner Barbaricum—A Multi-Method Approach

This article reports results of the geoarchaeological investigation of an early historical bloomery iron smelting site in northern Central Europe. Based on earlier field archaeological and experimental archaeological findings, which date back to an excavation in Sehnde (Hanover Region, Lower Saxony, Germany) in 2017, further experimental archaeological iron smelting experiments (furnace runs) have now provided information about the raw materials used in Sehnde during the Early Roman Imperial Period in Germania Magna (Inner Barbaricum) and the smelting process itself. The results of the present study suggest that no bog iron ore (BIOre) was smelted. Rather, manganese-rich carbonatic clay ironstone concretions (OCISCs) that had been oxidized by weathering and that were very rich in iron were apparently used as ores. Our study provides insights into metallurgical operations in the southern North German Plain during the Early Roman Imperial Period using a sampling and experimental archaeological test design created specifically for the local conditions.