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Chahak child and the crucible slag and a smithing slag layer. 	Source: 	Rahil Alipour, UCL

Cast Iron Evidence Of Ancient Persian Chromium Steel Production

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Scientists discover evidence of chromium production in ancient Persia, but historians at Sheffield in England defend the cities claim to having ‘invented’ the super-steel.

To many younger readers “Chromium code” is a free and open-source software project from Google, similar to the widely known Chrome browser, that most competing browsers are also based on, including Microsoft. However, to older readers, and to those of a scientific disposition, “Chromium surfaces” are produced on other metals to strengthen them, through “chromizing,” but what nobody of any age would have ever have guessed is that chromium steel, perhaps for use in weapons, originated in 11th century Persia.

Use of chromium oxide has been detected on the surface of excellently preserved weapons found at the site of the Terracotta Army in X’ian, China dating to the 3 rd century BC, but not use of the metal chromium on its own.

Discovering The Ancient Persian Alchemical Crucible

A new paper published in the  Journal of Archaeological Science by Dr Rahil Alipour and a team of UCLA scientists presents their discovery of a “chromium steel alloy,” which they found soldered onto a fragment of slag attached to a piece of a broken crucible. Even without including the word “crucible” this discovery can without argument be described as an alchemical revelation of magnificence, and the fragment of ancient alloy production containing the chromium was unearthed at an archaeological site in Fars province, southern Iran.

Chahak child and the crucible slag and a smithing slag layer. (Image: Rahil Alipour, UCL)

Chahak child and the crucible slag and a smithing slag layer. (Image: Rahil Alipour , UCL)

Chromium alloys afford steel products an anti-corrosive quality, and dating to the 11th century this discovery represents the “first known use of chromium to make a steel alloy,” and while chromium steel is similar to stainless steel, an alloy must have a chromium content of at least 10.5 per cent to be defined as stainless steel, and the traces of the alloy that had been forged with chromium discovered in Iran contained approximately one per cent.

Journey Of The Alchemical Hunters

This was in no way a chance discovery as team of researchers hunted for the evidence, first studying a series of historical manuscripts that recorded a prehistoric center of steel production called “Chahak.” This name is like “Mac” in Scotland, and there exist many villages called Chahak, but through a process of elimination they focused in on the Chahak in Fars province. The scientists’ suspicions that this was an ancient site where the secretive arts of metallurgy were practiced were justified in their discovery of charcoal within a crucible and smithing slags that when tested were found to contain between “one and two per cent “chromite ore,” according to the paper.

Crucible slag adhering to a crucible sherd and a broken Chahak crucible base where the crucible steel ingot would have solidified. (Image: Rahil Alipour, UCL)

Crucible slag adhering to a crucible sherd and a broken Chahak crucible base where the crucible steel ingot would have solidified. (Image: Rahil Alipour , UCL)

This finding, according to the researchers, is hard evidence that chromium was extracted from rocks and added to the alloy “on purpose,” and why this was undertaken take was for making “superior weapons and tools,” writes lead author Dr Rahil Alipour. The scientist also says this new research provides “the first evidence of the deliberate addition of a chromium mineral within steel production Chakak” and he thinks this might also explain why so many Persian blades discovered by archaeologists are in such good condition.

Turning Base Metals Into Gold, The Persian Way

Discovering that 11th century ancient Iranians were extracting, purifying and making alloys with chromium opens a new act in the show of ancient alchemy, which is generally presented in a European context, however, what still remains a tightly locked mystery in all this is what happened to this chromium alloy production system? The researchers say steel production ceased in the region after several centuries and therefore it was at this same time that those people who had served as keepers of the alchemical arts of extracting chromium from ore, melting and mixing it with other metals to make stronger weapons and tools, all but vanished, until the arts resurfaced in Britain in the early 20th century.

While most other articles about this discovery will present the ancient Iranian alloy as challenging the 20th century discovery of “stainless steel,” this modern metal is defined as a steel alloy that includes a minimum content of 10.5% Chromium, therefore English inventor Harry Brearley did make the first casting of a true “stainless steel” on 20th August 1913 in the city of Sheffield with an alloy containing 12.8 per cent chromium. But credit for having first extracted chromium for production purposes must now got to the 11th century Iranian alchemists who figured out how to turn lead into gold, or at least how to turn chromium into a harder substance: same thing, different elements.

Top image: Chahak child and the crucible slag and a smithing slag layer. Source: Rahil Alipour , UCL

By Ashley Cowie

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