The Ancient Metallurgical Engineering is still a mystery!!

The history of civilization is in many ways linked to the story of the use of metals in antiquity. Although modern metallurgy has seen an exponential growth since the Industrial Revolution it is interesting that many modern concepts in metallurgy have their seeds in ancient practices that pre-date the Industrial Revolution. 

The IRON PILLAR of Delhi, India is an Ancient Development which is still unsolved! Thinking why?

Just because it was built in about 912 BCE and still rust is far away from it! Till today its replica is yet to be made! (Though study has been done and we know its metallurgy!)