Chromium is a common addition to alloys to make materials like tool steel or stainless steel, and it’s long been thought to have been invented around the late 19th and early 20th centuries. But now, archaeologists have discovered that the ancient Persians were mixing chromium into their steel as far back as the 11th century – almost a thousand years earlier.
The team, led by Rahil Alipour of the University College London (UCL), studied several medieval Persian manuscripts and identified an archaeological site called Chahak, in southern Iran, as an ancient steel production site.
One manuscript in particular grabbed their attention. Titled al-Jamahir fi Marifah al-Jawahir, which translates to “A Compendium to Know the Gems”, the manuscript was written in the 10th or 11th century CE by the polymath Abu-Rayhan Biruni. Crucially, it contained the only known recipe for forging steel in high-temperature crucibles. The problem is, it can be difficult to follow a thousand-year-old recipe.
“The process of identification can be quite long and complicated and this is for several reasons,” says Marcos Martinon-Torres, last author of the study. “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 the modern science. Additionally, 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.”