Technological trajectories in iron smelting: slag signatures, recipes, and traditions from Phnom Dek (Cambodia, 7th–20th c. CE)

Abstract

International audienceThis study investigates the long-term dynamics of bloomery iron smelting practices across the Phnom Dek region of Cambodia, a major metallurgical landscape active from at least the 7th to 20th centuries CE. Based on pXRF analysis of more than 1,700 slag samples, it develops an interpretive framework that integrates multiple scales of evidence, combining chemical composition, spatial distribution, technical features, and chronological context. At the core of this approach is the identification of coherent chemical signatures in slag, which, by using multivariate analyses, function as proxies for metallurgical recipes, and, at a broader level, enduring technological traditions shaped by the social organization of production. These signatures serve as comparative units for tracing production behaviors across sites and time periods. Through the categories of practice and recipe, the analysis aims to identify patterns of continuity, adaptation, and transformation in iron-making processes or smelting behavior over time. Results point to significant changes in ore procurement and recipe during the 11th–12th centuries, likely linked to wider transformations within Angkorian state dynamics. The persistence of specific chemical profiles and regionally shared smelting practices beyond this period suggests a bloomery tradition sustained across the landscape. Ultimately, the study argues that the chemistry of slag, as a material trace of smelting activities derived from technical, spatial, and chronological contexts, has unique capabilities to acquire interpretive significance when analyzed across these dimensions. This approach enables the discussion of technological trajectories in iron production and the socio-technical logics that shaped the evolution of the Phnom Dek metallurgical landscape