Chromium Steel Was First Produced In Ancient Persia

Conny Waters – MessageToEagle.com – A new study led by UCL researchers shows that chromium steel was first made in Persia, nearly a millennium earlier than experts previously thought.

It was long believed that it was a 20th-century invention but the surprising and very important discovery based on a number of medieval Persian manuscripts, provides the first evidence of the deliberate addition of a chromium mineral within steel production.

Crucible slag adhering to the interior of a crucible sherd. Credit: Rahil Alipour, UCL

“We believe this was a Persian phenomenon,” said Dr. Rahil Alipour (UCL Archaeology), lead author on the study,  who added that the manuscripts led the researchers to an archaeological site in Chahak, southern Iran.

“This research not only delivers the earliest known evidence for the production of chromium steel dating back as early as the 11th century CE, but also provides a chemical tracer that could aid the identification of crucible steel artifacts in museums or archaeological collections back to their origin in Chahak, or the Chahak tradition.”

Chahak is described in a number of historical manuscripts dating from the 12th to 19th century as a once-famous steel production center and is the only known archaeological site within Iran, but the site’s location remains a mystery especially because many villages had this name in Iran.

The manuscript ‘al-Jamahir fi Marifah al-Jawahir’ (‘A Compendium to Know the Gems’, 10th-11th c. CE) written by the Persian polymath Abu-Rayhan Biruni, was of particular importance to the researchers given it provided the only known crucible steel making recipe.

Chahak people and the layer. Credit: Rahil Alipour, UCL

This recipe recorded a mysterious ingredient that they identified as chromite mineral for the production of chromium crucible steel.

Using radiocarbon dating of a number of charcoal pieces retrieved from within a crucible slag and a smithing slag (by-products left over after the metal has been separated), the team could date this ancient industry to the 11th to 12th century CE.

Additionally, it was possible to identify the remains of the ore mineral chromite, which was described in Biruni’s manuscript as an important addition to the process.

They also detected 1-2 weight percent of chromium in steel particles preserved in the crucible slags, demonstrating that the chromite ore did form chromium steel alloy—a process that we do not see used again until the late 19th and early 20th century.

“In a 13th-century Persian manuscript translated by Dr. Alipour, Chahak steel was noted for its fine and exquisite patterns, but its swords were also brittle, hence they lost their market value,” Professor Thilo Rehren (UCL Archaeology and The Cyprus Institute), a co-author on the study, said in a press release.

“Today the site is a small modest village, which prior to being identified as a site of archaeological interest, was only known for its agriculture.”

The researchers believe it marks a distinct Persian crucible steel-making tradition—separate from the more widely known Central Asian methods in Uzbekistan and Turkmenistan—for the production of low-chromium steel.

Professor Marcos Martinon-Torres (University of Cambridge), who also participated in the study, added that “the process of identification can be quite long and complicated and this is for several reasons.

“Firstly, the language and the terms used to record technological processes or materials may not be used anymore, or their meaning and attribution may be different from those used in modern science.”

“Additionally, the writing was restricted to social elites, rather than the individual that actually carried out the craft, which may have led to errors or omissions in the text.”

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Written by Conny Waters – MessageToEagle.com – AncientPages.com Staff Writer