An ancient copper foundry from 3,000 years ago could be key to clarifying the origins of iron in the transition between the Bronze and Iron Ages. By analyzing the site, a team of scientists believe they have discovered how ancient smelters invented iron.
The research, carried out by Cranfield University, in the United Kingdom, reveals how those first foundry artisans experimented with iron-rich rocks (hematites) until they discovered one of the most important metals in human history, iron.
To do the study, the team re-analyzed metallurgical remains from a site in southern Georgia, a 3,000-year-old foundry called ‘Kvemo Bolnisi’.
The site was studied in the 1950s, when the territory was part of the former Soviet Union, and piles of hematite (an iron oxide mineral) and slag (a byproduct of metal production) were found, leading to the belief that it was an iron workshop.
However, latest research showed that these assumptions were incorrect and that instead of iron, the craftsmen of Kvemo Bolnisi smelted copper using hematite as a flux, which was added to the furnace to increase the resulting copper yield.
The find supports a long-discussed theory that iron was invented by copper smelters. This evidence shows that ancient copper metallurgists experimented with iron-containing materials in a metallurgical furnace, which was a crucial step toward smelting iron.
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The importance of iron
Although the Iron Age marked the beginnings of widespread iron production, the metal itself was not a new discovery.
Iron artifacts dating back to the Bronze Age were found, the most famous being an iron dagger with a gold handle and rock crystal from the tomb of the Egyptian king Tutankhamun.
But the first iron objects were forged from iron extracted from meteorites, not artificially by smelting. That rarity meant that iron, at that time in history, was more valuable than gold but the development of extractive iron metallurgy changed everything.
Iron is one of the most abundant elements on Earth, although naturally occurring metallic iron is very rare.
The ability to extract iron from minerals and work it to turn it into tools or weapons is one of the definitive technological transformations in human history and that allowed everything from the formation of armed armies of antiquity to the railways and buildings of the industrial revolution.
Nathaniel Erb-Satullo, archaeologist at Cranfield University, explains that “iron is the world’s most iconic industrial metal, but the lack of written records, iron’s tendency to rust and the lack of research into iron production sites have made the search for its origins challenging.”
“That’s what makes this site at Kvemo Bolnisi so exciting. It’s evidence of the intentional use of iron in the copper smelting process, showing that these metallurgists understood iron oxide, the geological compounds that would eventually be used as ore for iron smelting, as a separate material and experimented with its properties inside the furnace.”
“Its use here suggests that this type of experimentation by copper workers was crucial to the development of iron metallurgy,” concludes the archaeologist.
With information from EFE
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