The mystery of the iron column in Delhi: why it has not rusted, because it is already 1600 years old

This unusual column is completely made of iron and is located in the city of Delhi. Its age is estimated at 1600 years, but despite this, no traces of rust were found on its surface, as is often the case with iron products located in the open air and not coated with anti-corrosion compounds.

The iron column in Delhi has a height of 7 meters and is almost 100% composed of pure iron. A detailed analysis of the composition carried out by Indian specialists showed only an insignificant (less than 0.5%) content of nickel and phosphorus in it. This column has a very interesting history. The fact is that she was not always in Delhi, on the territory of the Qutb Minar complex, but was transported there from the city of Mathura. But the exact date of this event is unknown, presumably this happened in the XI-XIII centuries. It is believed that the iron column was built in 415 in honor of Chandragupta II - the greatest ruler of the Gupta state, which existed on the territory of modern India. Initially, at the top of the iron column was a sculpture of a bird, but so far the column has lost its decoration.

For a long time it was believed that the column was cast from a single piece of iron, but research by scientists has shown that it is most likely made of several separate parts, and the total weight of the column is 6.5 tons. As you know, pure iron is subject to corrosion, therefore, in the modern world it is used in the form of alloys, which contain various components that protect it from moisture and oxygen. Given the fact that the column has no signs of damage, for a long time it was believed that it was made of a special alloy, the secret of which was known to the masters of antiquity.

But for centuries, the supported myth of the miraculous anticorrosive properties of the alloy was dispelled by a detailed study. It turned out that part of the column, which is underground, is exposed to moisture contained in the soil, it was preserved much worse and corroded by rust. But the aerial part, according to experts, survived 1600 years without significant damage, thanks to several factors. The main reason is the oxide film that formed on the surface of the column, making it chemically inert to atmospheric moisture. The formation of this film was promoted by particles of phosphorus, which was found in very small quantities in the composition of the column. In addition, in Delhi, dry and hot weather is most of the year, and significant precipitation occurs only from July to September, so the upper part of the column is in contact with moisture for a rather short time. It turns out that the researchers did not find any miraculous composition or technology of the ancient masters in the iron column, but saw only a chain of facts that all together led to the emergence of the myth of the stainless column.

Today, a fence is installed around the famous iron column: too many wanted to touch it, since it was believed that hugs with the column bring happiness and fulfill wishes. Nevertheless, it remains one of the Hindu pilgrimage sites, as well as a popular tourist attraction in the old part of Delhi.