On Wiki I found a link about cast iron being used in China in the 4 centruy BC. What I'm really looking for is some history or theories on the first uses of metal. From what I've been able to find the origins of humans using metal are lost in antiquity. I'm hoping someone here might have a better source than what I've been able to find on my own.
I think it's so interesting to imagine early humans wandering the savanah with their crude spears and noticing some discolored dirt or rocks and deciding to...? And that somehow leads to the Brooklyn Bridge.