A study by an international and interdisciplinary team led by University of Freiburg archaeologist Dr. Ralph Araque Gonzalez from the Faculty of Humanities has proven that steel tools were already in use in Europe around 2,900 years ago.
Using geochemical analyses, the researchers were able to prove that stelae on the Iberian Peninsula dating back to the Final Bronze Age have complex engravings that could only have been made with hardened steel. This was supported by metallographic analyzes of an iron chisel from the same period and region (Rocha do Vigio, Portugal, c. 900 BC) which showed the necessary carbon content to be proper steel. The result was also confirmed experimentally by conducting experiments with chisels made of different materials: only chisels made of hardened steel were adequately able to engrave the stone.
Until recently, it was thought that it had not been possible to produce suitable quality steel in the older Iron Age and certainly not in the Late Bronze Age, and that it first became widespread in Europe during the Roman Empire.
“The chisel from Rocha do Vigio and the context in which it was found show that iron metallurgy including the production and tempering of steel were probably indigenous developments of decentralized small communities in Iberia, and not due to the influence of later colonization processes. This also has implications for the archaeological assessment of iron metallurgy and quartzite sculptures in other regions of the world,” explains Araque Gonzalez.
The study, “Stoneworking and the earliest steel in Iberia: Scientific analyzes and experimental replications of Final Bronze Age stelae and tools,” has been published in Journal of Archaeological Science.
Iberian columns of siliceous quartz sandstone could only be machined with hardened steel
The archaeological record of Iberia from the Late Bronze Age (c. 1300-800 BC) is fragmentary in many parts of the Iberian Peninsula: sparse remains of settlement and almost no detectable burials are supplemented by traces of metal hoarding and remains of mining activity. Taken into account, the western Iberian stelae with their depictions of anthropomorphic figures, animals and selected objects are of unique importance for the study of this era.
Until now, studies of the actual rocks from which these stelae were made to gain insight into the use of materials and tools have been the exception. Araque Gonzalez and his colleagues analyzed the geological composition of the stelae in depth. This led them to discover that a significant number of stelae were not, as thought, made of quartzite, but silicate quartz sandstone.
– Just like quartzite, this is an extremely hard rock that cannot be worked with bronze or stone tools, but only with hardened steel, says Araque Gonzalez.
Chisel finds and archaeological experiments confirm the use of steel
Analysis of an iron chisel found in Rocha do Vigio showed that Iberian stonemasons from the Late Bronze Age had the necessary tools. The researchers discovered that it consisted of heterogeneous, yet astonishingly carbon-rich steel. To confirm their findings, the researchers also conducted an experiment involving a professional stonemason, a blacksmith and a bronze caster, attempting to work the stone from which the columns were made using chisels of different materials. The stonecutter could not work the stone with either the stone or the bronze chisels, or even use an iron chisel with an untempered point.
“Man in the Final Bronze Age in Iberia was able to harden steel. Otherwise, they would not have been able to work with the pillars,” Araque Gonzalez concludes as a result of the experiment.
Ralph Araque Gonzalez et al., Stoneworking and the Earliest Steel in Iberia: Scientific Analyzes and Experimental Replications of Final Bronze Age Stelae and Tools, Journal of Archaeological Science (2023). DOI: 10.1016/j.jas.2023.105742
More information is available here.
Journal of Archaeological Science