Evidence of Bronze Age smiths experimenting with iron for the first time has been uncovered.

Bronze tools and weapons were generally of superior quality to those made of iron, leading to questions over why it came to replace bronze as the metal of choice and why humanity moved from the Bronze to the Iron Age about 3,000 years ago.

Bronze is made of copper and tin, but the latter was hard to come by, making it difficult and expensive to massproduce bronze weapons and tools. Once smiths learnt how to smelt iron ore to extract the iron, it was a cheaper and more abundant metal. This helped to fuel the expansion of agriculture and warfare, as it became easier to equip large armies with weapons.

Iron was used as a metal before the Iron Age, but this mostly came from naturally occurring iron found in meteorites, making it extremely rare and more valuable than gold.

Scientists have been trying to pinpoint how, when and where early workshops started experimenting with the extraction of iron and have analysed metal found at a 3,000-year-old smelt- ing site in southern Georgia called Kvemo Bolnisi.

When it was first analysed in the 1950s, scientists found piles of haematite, an iron oxide mineral, and also slag, a waste product, and thought they had found an early iron workshop.

Analysis has now found that the workshop was actually a site for smelting copper, a key ingredient in bronze, and the iron oxide was being added into the furnace to help extract more copper, according to a study in the Journal of Archaeological Science.

It shows these ancient copper metalworkers were starting to “experiment with iron-bearing materials in a metallurgical furnace, which was a crucial step towards iron smelting”, according to the researchers from Cranfield University in Bedford.

Nathaniel Erb-Satullo of Cranfield said: “Iron is the world’s quintessential industrial metal, but the lack of written records, iron’s tendency to rust and a lack of research on iron production sites has made the search for its origins challenging.

“That’s what makes this site at Kvemo Bolnisi so exciting. It’s evidence of intentional use of iron in the coppersmelting process.”