ROHITH M.
Google
Iron Pillar is an ancient Indian metallurgical marvel, dating back to the Gupta Empire in the 4th century CE. Standing over 7 meters tall and weighing more than six tons, it is famous for its remarkable resistance to rust, despite being exposed to the elements for over 1,600 years.
Iron Pillar bears an inscription in Sanskrit in Brahmi script of fourth century A.D., according to which the pillar was set up as a Vishnudhvaja (standard of god Vishnu) on the hill known as Vishnupada in memory of a mighty king named Chandra.
History and origins:
Construction: The pillar was originally erected by King Chandragupta II (375–415 CE), a Gupta emperor, who is widely identified as the "King Chandra" mentioned in its inscriptions.
Original location: It is believed the pillar was initially installed at a site called Vishnupadagiri (likely modern Udayagiri in Madhya Pradesh) and was topped by a figure of Garuda, the divine eagle mount of the Hindu deity Vishnu.
Relocation: The pillar was moved to its current location in the Qutb complex in Delhi, though the exact timing and reasons are debated. The Tomar king Anangpal is credited by some with moving it in the 11th century, while others suggest it was moved as a war trophy by Sultan Iltutmish in the 13th century.
Current location: Today, it stands prominently in the courtyard of the Quwwat-ul-Islam Mosque within the Qutb complex, a UNESCO World Heritage site.
Rust-resistant composition:
For many years, the pillar's ability to resist corrosion puzzled scientists. However, modern research has uncovered the ingenious metallurgy behind it.
High phosphorus content: Ancient Indian blacksmiths did not use limestone flux in their iron furnaces, resulting in iron with an unusually high phosphorus content (around 1%).
Protective film: This high phosphorus, combined with Delhi's dry atmospheric conditions, promotes the formation of a thin, passive protective layer of crystalline iron hydrogen phosphate hydrate (misawite) on the surface of the pillar.
Shielding effect: This layer acts as a barrier, shielding the iron from oxygen and moisture and effectively preventing it from rusting.
Enduring legacy:
The Iron Pillar remains a powerful testament to the advanced scientific and engineering knowledge of ancient India. Its construction required advanced metallurgical skill and a deep understanding of material science that was ahead of its time. The pillar's enduring strength is a symbol of India's long history of innovation.