Research from Cranfield University has provided exciting insights into the transition from the Bronze Age to the Iron Age. It turns out that early copper smelters experimenting with iron-rich rocks may have played a key role in the invention of iron.
This research involved a reexamination of metallurgical remains at Kvemo Bolnisi, a 3,000-year-old smelting workshop located in southern Georgia. During the original analysis conducted in the 1950s, excavators discovered piles of hematite (an iron oxide mineral) and slag (a byproduct of metal production). Initially, these findings led researchers to believe that the workshop was an early site for iron smelting.
However, new findings reveal that the workers at Kvemo Bolnisi were actually smelting copper and using iron oxide as a flux—an additive that enhances the yield of copper from the smelting process.
These results lend credence to a long-held theory that copper smelters were instrumental in the invention of iron. The evidence suggests that ancient metalworkers were experimenting with iron-rich materials in their furnaces, a crucial step toward developing iron smelting technology.
The Importance of Iron
The Iron Age marked the beginning of widespread iron production, although iron itself wasn’t a recent discovery. Artifacts made of iron have been found dating back to the Bronze Age, including a famous iron dagger with a gold and rock crystal hilt found in the tomb of the Egyptian king Tutankhamun. Early iron objects were crafted from naturally occurring metallic iron found in meteorites, as opposed to being extracted from iron ore through smelting. This rarity made iron, at that time, more valuable than gold.
The advancement of iron metallurgy fundamentally changed this dynamic. Although iron is one of the Earth’s most abundant elements, natural iron metal is quite rare. The ability to extract iron from ore and transform it into useful materials, such as tools and weapons, marked a significant technological leap in human history. The transition to the Iron Age was gradual but ultimately gave rise to the iron-powered armies of Assyria and Rome, as well as the railroads and steel structures of the industrial revolution.
Dr. Nathaniel Erb-Satullo, a Visiting Fellow in Archaeological Science at Cranfield University, stated, “Iron is the world’s quintessential industrial metal, but the lack of written records, its propensity to rust, and limited research on iron production sites have complicated the search for its origins.”
He added, “What makes Kvemo Bolnisi so exciting is the evidence that iron was intentionally used in the copper smelting process. This shows that ancient metalworkers recognized iron oxide as a distinct material and experimented with its properties in their furnaces. This kind of experimentation by copper workers was crucial for the development of iron metallurgy.”
Dr. Erb-Satullo concluded, “There’s a beautiful symmetry in this research; modern geology and materials science techniques allow us to delve into the thinking of ancient materials scientists—using slag, a seemingly mundane waste material that resembles odd lumps of rock.”
This research was supported by grants from the British Institute of Ankara, the Gerda Henkel Foundation, and the American Research Institute of the South Caucasus. The findings were published in the paper Iron in copper metallurgy at the dawn of the Iron Age: Insights on iron invention from a mining and smelting site in the Caucasus in the Journal of Archaeological Science.
Summary: Recent research from Cranfield University reveals that ancient copper smelters at the Kvemo Bolnisi workshop were experimenting with iron oxide, a process vital to the eventual invention of iron. This discovery highlights the integral role of copper workers in the transition from the Bronze Age to the Iron Age, showcasing how early experimentation laid the foundation for iron metallurgy, one of the most significant technological advancements in human history.
