Reconstructing the iron production technologies of western Uganda: reconciling archaeometallurgical and ethnoarchaeological approaches

Abstract

The local production of iron was an important technology in eastern Africa up until the later twentieth century, when the use and reuse of imported iron overtook vernacular smelting industries and cemented their decline. Prior to this, the utilisation of local ores had produced iron for agricultural implements, household tools and weapons, serving the needs of many generations of farmers and herders across the region.The smelters of western Uganda enjoyed a particularly esteemed reputation in recent history, especially among their neighbours in Buganda, yet prior to this research little was known about the technologies upon which this reputation was fostered. This thesis presents the results of six months of fieldwork in Uganda and subsequent archaeometallurgical analysis, which together revealed the complexities of smelting in western Uganda between the fourteenth and twentieth centuries.Exploring this new archaeometallurgical dataset has indicated that some iron producers in Mwenge (a particularly iron-rich region of western Uganda) were selecting manganese-rich ores with which to supplement the iron ores in the smelt, imparting a tangible effect on the process and outcomes of these smelting episodes, hypothetically increasing the metal yield and improving operating parameters.Although such harnessing of beneficial manganese-rich minerals was an unexpected and unusual finding, technological reconstructions of these smelts highlighted several other interesting features, including the consistent use of grog temper in technical ceramics, the occasional use of banana pseudostems, and variations in furnace style.Combining these discoveries with existing ethnoarchaeological and ethnohistorical data, and building upon social approaches to iron technologies, it was possible to explore some of the possible reasons for this variation, adding colour and time-depth to the understanding of iron production within this region.4

The exploitation of manganese-rich ‘ore’ to smelt iron in Mwenge, western Uganda, from the mid second millennium AD

“…The research presented here adds a further African example of bloomery smelting using a manganese-rich charge (Iles 2011). Analysis of slag from six iron smelting sites in Mwenge, western Uganda revealed manganese oxide levels ranging up to 12wt%.…”

“…It is estimated that each of the sites discussed here contained a maximum of between 50 and 100 slag blocks. This relatively low volume of extant slag is likely to be related at least in part to the widespread practice of reusing slag blocks as a construction material (Iles 2011).…”

“…These dates provide a time frame for the operation of the individual furnaces themselves, but cannot be said to be representative of the total operational period of the sites nor directly related to the sampled slag blocks. The full results of the survey and excavation are reported elsewhere (Iles 2009a(Iles , 2011(Iles , 2013.…”

“…FeO). The slag from the site of Mirongo separates into both manganese-poor (samples MNGa-h) and manganese-rich (samples MNGi-n), which derived from two distinct and separate areas of the site (Iles 2011). The manganese-poor samples were excavated from the furnace itself and its immediate area, and are thus considered to be more closely linked to the c. 14 th -15 th century AD date obtained from this site.…”

The development of iron technology in precolonial western Uganda

“…We know from the aforementioned historical accounts as well as from ethnoarchaeological studies (e.g. Over 200 sites were found and detailed descriptions of the results of the fieldwork are available elsewhere (Iles 2009(Iles , 2011. This strong, durable material was central to the early foundations of what were to become powerful kingdoms in the region until colonial disruption in the nineteenth and twentieth centuries.…”