The researchers of the study published in the Journal of Archaeological Science

This was supported by metallographic examinations of an iron chisel from the same time and place (Rocha do Vigio, Portugal, c. 900 BCE), which revealed the required carbon concentration for good steel. The outcome was further supported empirically by experiments with chisels composed of various materials: The only tool that could effectively engrave the stone was one made of tempered steel. It was once believed that it was impossible to create steel of a sufficient quality during the Early Iron Age and most definitely not during the Late Bronze Age, and that it was only during the Roman Empire that it became common in Europe.

The Rocha do Vigio chisel and the environment in which it was discovered demonstrate that iron metallurgy, particularly the manufacturing and tempering of steel, were likely indigenous developments of decentralized tiny settlements in Iberia and not under the influence of later colonization activities. This has implications for how quartzite sculptures and iron metallurgy are evaluated archaeologically in other parts of the world.

The Late Bronze Age (c. 1300-800 BCE) archaeological record of Iberia is patchy in many areas of the Iberian Peninsula. There are few signs of settlement and almost no discernible burials, although there are signs of hoarding of metal and signs of mining activity. In light of this, the western Iberian stelae, with their representations of anthropomorphic figures, animals, and particular items, are of particular significance for the study of this period.

Studies of the actual rocks from which these stelae were carved in order to learn more about the materials and tools that were used up until this point have been the exception. The authors conducted a thorough analysis of the stelae's geological makeup. As a result, they found that a silicate quartz sandstone, rather than quartzite, was used to make a sizable number of stelae. Similar to quartzite, this incredibly hard rock can only be worked with tempered steel, not bronze or stone tools.

The Rocha do Vigio iron chisel's analysis revealed that Iberian stonemasons from the Last Bronze Period had the required equipment. The scientists found that it was made of steel, which was amazingly heterogeneous and rich in carbon.

The researchers also conducted an experiment including a master stonemason, a blacksmith, and a bronze caster in which they sought to shape the rock from which the pillars were produced using chisels made of various materials in order to corroborate their findings. Stone or bronze chisels, or even an iron chisel with an untempered point, could not be used by the stonemason to carve the stone.

The inhabitants of Iberia's Last Bronze Age were skilled in tempering steel. They could not have masoned the pillars without it.