Iron and its influence on the prehistoric site of Lejja

Nyame Akuma, 2013

Proceedings of the 36th International Symposium on Archaeometry, p. 453-463, 2009

Bloom smelting in West Africa has a long tradition dating back to the second half of the second millennium BC. By the time the colonial iron replaced the indigenous production around the end of the 19th century, this craft had locally developed into a major industry with an outstanding technological variability. The Dogon Plateau, located in Mali at the margin of the interior delta of the Niger, is well known for it's rich traditions and a remarkable material culture. Until recently however, the knowledge of the Dogon iron metallurgy was restricted to the eastern border of the Plateau. In the framework of the interdisciplinary and international research program "Human population and palaeoenvironment in West Africa", an ongoing research project aims to understand the development of the iron production on the Dogon Plateau. It appears that there are numerous remains of iron production, showing a large variability in furnace design and waste assemblage, and at least six groups could be differentiated based on these remains. In this paper, we present the smelting site of Fiko (6th-19th c. AD), which has been investigated by archeological and archaeometric methods. The metallurgical remains are discussed, and the iron production quantified.

Oxford Research Encyclopedia of African History, 2017

Iron production was a particularly important precolonial African technology, with iron becoming a central component of socioeconomic life in many societies across the continent. Iron-bearing ores are much more abundant in the earth's crust than those of copper, and in Africa, iron was recovered from these ores using the bloomery process, until the importation of European iron in the later second millennium eventually undermined local production. Although smelting was most intensively focused in regions where all the necessary components of a smelt were plentiful—iron ore, ceramic, fuel, and water—frequent occurrences of small-scale, local iron production mean that iron slag and associated remains are common finds on archaeological sites across Africa. The archaeological remains found on iron production and iron-working sites can provide detailed information about the past processes that were undertaken at these sites, as well as the people involved with the technologies both as practitioners and consumers. A variety of analytical approaches are commonly used by archaeometallurgists to learn more about past iron technologies, particularly those methods that explore the chemistry and mineralogy of archaeological samples. By interpreting the results of these analyses in conjunction with ethnographic, historical, and experimental data, it is possible to reconstruct the techniques and ingredients that past smelters and smiths employed in their crafts, and address important questions concerning the organization of production, the acquisition of raw materials, innovations and changes in technological approach, and the environmental and social changes that accompanied these technologies.

Nyame Akuma, 2009

Journal of African Archaeology 11(1): 39-54, 2013

In 2008, a number of iron artefacts were recovered from an interior courtyard on the DGB-1 site during fieldwork in 2008. DGB-1 is a large multi-function site located in the northeastern Mandara Mountains of Cameroon, and dating to the mid-second millennium AD. The iron artefacts recovered included a cache of spear/arrow points found buried under a living floor, as well as a local hoe and a chain and a ‘barrette’ probably not of local provenance. This discovery has a number of points of interest: (1) ethnoarchaeological reenactments of iron smelts in the 1980s in the same region provide a rare opportunity for comparison of iron-working techniques over about five centuries in sub-Saharan Africa; (2) the variability in different forms of iron (including eutectoid steel) used in these artefacts; and (3) the welding of different forms of iron to produce composite artefacts.

We present luminescence dates which demonstrate a full-blown smelting technology in Northern Ghana, West Africa, during the Early Iron Age. Our chronology is based on thermoluminescence (TL) dating of quartz grains extracted from the walls of three iron smelters located at the Birimi site in the Northern Region of Ghana. Two of the smelters yielded statistically indistinguishable ages of 1080±70 and 1090±60 years, while the third yielded a higher age of 1600±100 years. All are significantly older than the sole direct radiocarbon date of 550–330 calBP (460±90 BP) obtained on a furnace in the Northern Region. The TL ages indicate that iron smelting was well established in the Northern Region before the middle of the first millennium AD, and corroborate the validity of a number of similarly early radiocarbon dates associated with Early Iron Age ceramics but not directly associated with smelting activity, from other sites in northern Ghana. The iron working remains at Birimi are located on a river terrace, only a few tens of meters west of a dense Kintampo occupation. Radiocarbon and TL dates for the Kintampo complex demonstrate that the Iron Age and Kintampo components at Birimi are clearly non-contemporaneous. The occurrence of two distinct layers of goethite within 150 cm of the terrace surface, both of which are clearly exposed in the scarp of the terrace upon which the smelters are situated, indicates that the industrial site was deliberately sited to take advantage of the readily available source material. This premise is confirmed by geochemical analyses of sediment, goethite, and slag from the smelting site. We therefore propose that the frequent proximity of Kintampo and iron production sites is incidental, in the sense that each group exploited different resources offered by a riverbank location.

Journal of African Archaeology, 2013

In 2008, a number of iron artefacts were recovered from an interior courtyard on the DGB-1 site during fieldwork in 2008. DGB-1 is a large multi-function site located in the northeastern Mandara Mountains of Cameroon, and dating to the mid-second millennium AD. The iron artefacts recovered included a cache of spear/arrow points found buried under a living floor, as well as a local hoe and a chain and a 'barrette' probably not of local provenance.

Journal of Archaeological and Anthropological Sciences, 2023

This paper presents the most extensive archaeometallurgical study of iron-smithing debris excavated in East Africa. It presents an integrated methodology, including morphological, chemical, petrographic, and contextual analysis of iron slag excavated from secondary ironworking contexts. Iron slag from three Swahili sites was analysed-Unguja Ukuu located on the southwestern coast of Zanzibar, and Tumbe and Chwaka situated in the northeast of Pemba Island. The results suggest that Unguja Ukuu smithing is associated with oxidising hearth atmospheres and high amounts of CaO, while slag from Tumbe and Chwaka indicates reducing hearth atmospheres and high silica:alumina ratios, potentially pointing to the use of a flux. Distinct technical traditions can be seen at Unguja Ukuu when compared to Tumbe and Chwaka, suggesting a regional rather than chronological pattern. Temporal continuity is evident throughout the occupation of Unguja Ukuu and between sites of different periods in northwestern Pemba. The spatial distribution of iron slag at these sites suggests that smithing was taking place across the extent of Unguja Ukuu, while slag scatters were more localised and disassociated from domestic contexts at Tumbe and Chwaka. The wealth of information on technological and organisational aspects of smithing obtained during this study indicates that an integrated methodology can yield valuable data for a variety of smithing sites, irrespective of excavation strategies.

Archaeological and Anthropological Sciences, 2017

Recent excavations of a Late to Post-Meroitic furnace workshop at Meroe, Sudan prompted questions concerning the use of some of its unusual design features and the nature of ironmaking practice. To begin addressing these questions, four iron smelting experiments were conducted in a purpose-built workshop modelled from the archaeological remains. Some of the goals of the campaign included identification and testing of potential ore and technical ceramic resources as well as the production of slag with characteristics that mirrored those of the archaeological deposits. The primary objective, however, was the further development of a model for Late to Post Meroitic direct process iron production. Comparison of the microstructural and chemical characteristics of the archaeological and experimental ironmaking residues leads to a rejection of hypothesized ore sources adjacent to Meroe, support for hypothesized technical ceramic resource locations, and a failure to replicate Late-Post Meroitic smelting slag. However, the comparison also makes a strong contribution to the developing model of smelting practice at Meroe by emphasizing the need to create more consistent redox conditions within the furnace, greater standardization in preparing technical ceramics and the use of relatively lean ores (≈60 wt % Fe).

Azania: Archaeological Research in Africa, 2014

The fourteenth-century AD furnace at the earthworks site of Munsa is one of the earliest dated examples of iron smelting remains from western Uganda. The furnace is situated on a large, flat area at the centre of the earthworks, screened from the rest of the site by granite boulders. This paper presents and discusses the archaeological context of the furnace and the archaeological remains that were associated with it. It is likely that future excavation at Munsa would reveal further furnace remains, adding to the increasing body of knowledge about the development of iron production in western Uganda.