https://phys.org/news/2025-09-year-copper-smelting-site-key.html Phys.org Topics * Week's top * Latest news * Unread news * Subscribe [ ] Science X Account [ ] [ ] Sign In Sign in with Forget Password? Not a member? Sign up Learn more * Nanotechnology * Physics * Earth * Astronomy & Space * Chemistry * Biology * Other Sciences * Medical Xpress Medicine * Tech Xplore Technology [INS::INS] * * share this! * 102 * Tweet * Share * Email 1. Home 2. Other Sciences 3. Archaeology * * * --------------------------------------------------------------------- September 26, 2025 The GIST A 3000-year-old copper smelting site could be key to understanding the origins of iron by Cranfield University edited by Robert Egan [Robert] Robert Egan associate editor Meet our editorial team Behind our editorial process Editors' notes This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: fact-checked peer-reviewed publication trusted source proofread How a 3000-year-old copper smelting site could be key to understanding the origins of iron Copper smelters at the site used copper ores that lacked iron. Adding the iron oxide hematite to the furnace helped the copper metal to separate more easily from the impurities in the ore. Credit: Dr. Nathaniel Erb-Satullo Research from Cranfield University sheds new light onto the transition from the Bronze Age to the Iron Age, showing how experimentation with iron-rich rocks by copper smelters may have sparked the invention of iron. Published in the Journal of Archaeological Science, the work reanalyzed metallurgical remains from a site in southern Georgia: a 3000-year-old smelting workshop called Kvemo Bolnisi. During the original analysis in the 1950s, piles of hematite (an iron oxide mineral) and slag (a waste product of the metal production) were found in the workshop. Finding those iron oxides, the original excavators thought the workshop was an early iron smelting site. However, new research shows that those assumptions were wrong. Rather than iron, workers at Kvemo Bolnisi were smelting copper using iron oxide as a flux--a substance added into the furnace to increase the resulting copper yield. These discoveries give weight to a long-discussed theory that iron was invented by copper smelters. This evidence shows that ancient copper metalworkers experimented with iron-bearing materials in a metallurgical furnace, which was a crucial step towards iron smelting. How a 3000-year-old copper smelting site could be key to understanding the origins of iron Sparkly hematite mineral was used as a flux by copper smelters. Its distinctive appearance may have helped to attract attention from ancient miners and prospectors. Credit: Dr. Nathaniel Erb-Satullo The importance of iron While the Iron Age marked the beginnings of widespread iron production, the metal itself wasn't a new discovery. Iron artifacts have been found dating from the Bronze Age, most famously an iron dagger with a gold and rock crystal hilt from the tomb of Egyptian king Tutankhamun. But the earliest iron objects were forged from naturally occurring metallic iron found in meteorites, not extracted from iron ore through smelting. That rarity meant iron was, at that point in history, more valuable than gold. [INS::INS] The development of extractive iron metallurgy changed all this. Iron is one of the most abundant elements on Earth, even though naturally occurring iron metal is very rare. The ability to extract iron from iron ore and work it into useful materials such as tools or weapons is one of the defining technological transformations in human history. The transition into the Iron Age was far from instantaneous, but it gave rise to the iron-wielding armies of Assyria and Rome and later the railroads and steel-frame buildings of the industrial revolution. * How a 3000-year-old copper smelting site could be key to understanding the origins of iron A scanning electron microscope was used to analyze the chemistry, mineralogy, and microstructure of the samples. Credit: Dr. Nathaniel Erb-Satullo * How a 3000-year-old copper smelting site could be key to understanding the origins of iron The site, shown here, was originally excavated during the Soviet period and was relocated using hand draw maps from a 1964 book. Credit: Dr. Nathaniel Erb-Satullo Dr. Nathaniel Erb-Satullo, Visiting Fellow in Archaeological Science at Cranfield University, 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 copper smelting process. That shows that these metalworkers 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 within the furnace. Its use here suggests that this kind of experimentation by copper-workers was crucial to development of iron metallurgy. "There's a beautiful symmetry in this kind of research, in that we can use the techniques of modern geology and materials science to get into the minds of ancient materials scientists. And we can do all this through the analysis of slag--a mundane waste material that looks like lumps of funny-looking rock." More information: Iron in copper metallurgy at the dawn of the Iron Age: Insights on iron invention from a mining and smelting site in the Caucasus, Journal of Archaeological Science (2025). DOI: 10.1016/ j.jas.2025.106338 Journal information: Journal of Archaeological Science Provided by Cranfield University Citation: A 3000-year-old copper smelting site could be key to understanding the origins of iron (2025, September 26) retrieved 2 October 2025 from https://phys.org/news/ 2025-09-year-copper-smelting-site-key.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. 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This supports the theory that experimentation with iron-bearing materials by copper smelters was a key step toward the development of iron metallurgy, marking a significant transition from the Bronze Age to the Iron Age. This summary was automatically generated using LLM. Full disclaimer Let us know if there is a problem with our content Use this form if you have come across a typo, inaccuracy or would like to send an edit request for the content on this page. For general inquiries, please use our contact form. For general feedback, use the public comments section below (please adhere to guidelines). Please select the most appropriate category to facilitate processing of your request [-- please select one -- ] [ ] [ ] [ ] [ ] [ ] Your message to the editors [ ] Your email (optional, only if you'd like a response) [ ] Send Feedback Thank you for taking time to provide your feedback to the editors. Your feedback is important to us. 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