Ancient Hindu Science
The Rig Veda in its present form is at least 25000 years old.
Thus, we can see that at least 25000 years ago, ancient Hindus knew the use of many metals like gold, silver, bronze, iron, steel, etc.
In a Rig Vedic mantra, the sage speaks of having received a vessel, “fresh from the oven”, which was made of steel or some other metal.
So stone age has nothing to do with ancient India. “We got 4000 cows from Rushamas. They also gave us a huge shining steel vessel. It was fresh-from-fire, sweating,and strong.” Rigveda Samhita 220.127.116.11.