An iron pillar that has not been worn for the last 1600 years

The Iron Pillar of Delhi is a fascinating example of ancient Indian metallurgy and engineering. Standing at about 7.21 meters (23.6 feet) tall and weighing around 6 tons, this iron pillar is notable for its remarkable resistance to corrosion, despite being exposed to the elements for over 1,600 years. Located in the Qutb complex in Delhi, India, the Iron Pillar dates back to the 4th century CE, during the reign of Chandragupta II (also known as Vikramaditya). What makes this pillar especially intriguing is the fact that it has remained largely unaffected by rust, even though it is made from a relatively pure form of iron and has been exposed to Delhi’s humid climate for more than a millennium and a half.

The secret to its durability lies in the unique composition of the iron. The pillar is made from high-quality iron with a combination of iron and other elements, such as phosphorus, which may have contributed to a protective coating on the surface. This coating acts like a passive layer that prevents further corrosion. Additionally, the pillar was made using advanced metallurgical techniques, which are still not entirely understood. The inscriptions on the pillar, written in Sanskrit, offer clues about its historical significance and its origins, though the exact reasons for its creation remain somewhat mysterious. The iron pillar is a testament to the advanced metallurgical skills of ancient India and continues to be a subject of research and fascination.