Metallurgy was well known by the Guptas, as can be attested to by the iron pillar of Delhi.
Explanation:
DelhiIron Pillar is a seven meter high iron column that is part of the Qutb Complex, located in Delhi, India, and which is famous for its rust-resistant composition of the metals used in its construction. The pillar has attracted the attention of archaeologists and metallurgists and has been classified as "a testimony that metallurgy was well known by the Guptas" because of its high resistance to corrosion. The results of corrosion resistance tests of a uniform crystalline layer of iron phosphate and hydrogen formed phosphorus with high iron content, which serves to protect the pillar from the effects of the local climate of Delhi. It is believed that the name of the city of Delhi was inspired by a legend associated with the pillar.
