Negotiating between iron and bronze traditions: The impact of a tool - The chisel from Rocha do Vigio

This study presents new metallographic and microhardness data from the working tip of an iron chisel from Rocha do Vigio, south-western Iberia, dated to the ninth century BCE. Previous analyses of the butt section established the artefact as a bloomery steel, but the cutting end had not been examined. The new observations reveal a homogeneous, very fine pearlitic to pearlitic-bainitic structure with limited ferrite and no martensite, indicating faster but not fully quenched cooling. Vickers hardness values corroborate a modest mechanical gradient between the softer butt and the refined tip, consistent with thermal control during forging. The alloy’s low manganese content indicates that the hardenability of bloomery steels differs markedly from modern reference compositions, highlighting the need for transformation data specific to low-Mn systems. The site’s associated smelting slags confirm local primary iron production. Together, these results suggest that the Rocha do Vigio chisel embodies a deliberate adaptation of Bronze-Age thermal working practices to the novel material of steel, illustrating that early iron metallurgy in Iberia evolved through continuity of skill rather than technological rupture.