The Quest for Laterite Smelting in Mainland Southeast Asian Pre-Industrial Societies: An Archaeometallurgical Investigation of Ban Kruat Remains, Buriram Province, Thailand

Department of Archaeology, Faculty of Archaeology, Silpakorn University, Thailand

Despite iron having long been regarded by Prof. Higham and others as a crucial commodity impacting the trajectory of economic, political, and social history of Northeast Thailand, the theory faces a major problem in that there is an absence of typical iron ore deposits in the region. However, iron-bearing laterite deposits have long been suggested to be a potential alternative, dependent upon their quality, but few investigations have attempted to assess this possibility using an archaeometallurgic perspective. The archaeological investigations at Ban Kruat, Thailand offer a new opportunity to scrutinise how iron was extracted from laterite and what strategy was needed to achieve the desired metal. Slag, technical ceramics, and lateritic fragments recovered archaeologically were subjected to microstructural and chemical analysis. The analytical results showed a promising picture of the use of particularly high-grade laterite being exploited and smelted. The process involved the smelting of locally available iron and alumina-rich laterite ores inside shaft furnaces under unusually high temperatures and reducing atmospheres, possibly leading to the direct production of carbon-rich iron (steel). Comparing different workshops in Ban Kruat, the analysis suggested the very low technical variability of this practice between smelters, which may have been critically constrained by the ore chemistry. This rendered this technology rather resistant to change or improvement, in spite of the profound changes taking place concurrently in lower Northeast Thailand, ranging from the political to the socioeconomic.