Mystery of Delhi's Iron Pillar unraveled Press Trust Of India Thursday, July 18, 2002 New Delhi, July 18: Experts at the Indian Instituteof Technology have resolved the mystery behind the 1,600-year-old iron pillar in Delhi, which has never corroded despite the capital's harsh weather. Metallurgists at Kanpur IIT have discovered that a thin layer of "misawite", a compound of iron, oxygen and hydrogen, has protected the cast iron pillar from rust. The protective film took form within three years after erection of the pillar and has been growing ever so slowly since then. After 1,600 years, the film has grown...