Metals known to the Harappans
Variety of metals such as copper, gold, silver was extensively used by the Harappan metal workers.
Minor metals like tin, arsenic, lead, antimony etc. were used for alloying.
They had also perfected the intricate ciré perdue or lost wax technique of metal casting as early as the third millennium BCE.
But, Iron was not known to the people of Indus Valley Civilisation.
Iron was first used in the later Vedic Period by the Aryans. It was known as shyam ayas means black or dark metal.
In Indus valley civilization, manufacture of polished bronze and copper mirrors goes back to the time between 2800 and 2500 BC.
Bronze and copper mirrors preceded the glass mirrors of today. These mirrors were made as polished reflective surfaces on metals, commonly bronze or copper. They used by the elites amongst the Harappans.