Slag analyses from archaeological iron smelting sites are common. Rigorous analyses of iron and slag from successful experimental smelting, however, are still rare. Furthermore, thorough analyses from a series of smelts, and of the slag produced in different phases of the smelt, are exceedingly rare. The present study investigates the effect of an iron smelter’s decision-making and skills on the products of the smelting process: iron and slag. Four smelting experiments were carried out in a shaft furnace with slag tapping using iron ores from the Southern Levant. Using various analytical techniques, including portable X-ray fluorescence, optical and electron microscopy, metallography, and hardness tests enabled us to correlate the properties of the final products with adjustment of various parameters during the smelting process. The latter include airflow and charging rate, temperature, residence time in the reducing zone, ore-charcoal ratio, and control of the slag characteristics. Results obtained allowed us to empirically demonstrate the direct impact of decisions made by the smelter during the complex technological practice of bloomery smelting. Analysis also highlights the benefits of moderately reducing conditions controlled by the smelter to produce good-quality, low-carbon iron, which is particularly relevant within the geological setting of the Southern Levant.

The innovation of iron production is often considered one of the greatest technological advances in human history. A reliable provenancing method for iron is instrumental for the reconstruction of economic, social and geo-political aspects of iron production and use in antiquity. Although the potential of osmium isotopes analysis for this purpose has been previously suggested, here we present for the first time the results of osmium isotope analysis of ores, bloom and metal obtained from a set of systematic, bloomery iron-smelting experiments, utilizing selected ores from the Southern Levant. The results show that the 187Os/188Os ratio is preserved from ore to metal, with no isotopic fractionation. In addition, enrichment/depletion of osmium content was observed in the transition from ore to metal and from ore to slag. This observation has potential significance for our ability to differentiate between the various processes and sheds light on the suitability of various production remains for this method, which emerges as a robust and promising tool for the provenancing of archaeological ferrous metals.

The Royal City of Meroe, ca. 200 km north of Khartoum in the modern-day Republic of the Sudan, was an ancient capital of the Kingdom of Kush. From the 3rd century b.c. to the 4th century a.d., Kushite rulers controlled significant territory from the banks of the Nile at Meroe, in part through their ability to ensure the production of significant quantities of iron. The extensive archaeological remains of Meroitic iron production have been investigated over decades, and recently a series of experimental iron smelts in a replica Meroitic furnace has shed new light on the archaeometallurgical evidence. The data generated during the smelting campaigns has provided an understanding of the type of iron ore used, the construction and operating parameters of the furnace, and the workshop space created by the ancient iron smelters during the later and post-Meroitic times.

For several years, we have explored many aspects of the process of bloomery smelting in a shaft furnace. In contrast to most attempted reconstructions of bloomery smelting, our work has focused on the process itself, rather than its archaeological signatures. This paper describes a typical smelt of the most efficient regimen we have yet discovered. We will pay particular attention to methods that differ from those of most experimenters, especially with regard to blowing rate, slag management, and the recycling of furnace products. A bloomsmithing experiment is also described, and yields, resources, and labour requirements are quantified. We then offer a few observations where our experience differs from what we have read in the literature. Finally, we suggest that these methods, when applied to archaeological reconstructions of ancient bloomeries, may provide some missing answers for the archaeometallurgical community.