Metallurgy was well known by the Guptas as shown by the pillar of Delhi.?

The pillar in Delhi, known as the Iron Pillar of Qutub Minar, is made of wrought iron and is a testament to the advanced metallurgical skills of the Gupta period. The pillar's resistance to corrosion is due to the high phosphorus content in the iron and the presence of a protective passive layer. This indicates that the Guptas had a sophisticated understanding of Metallurgy and metalworking techniques.