Discovery of Metal
Well, I always make mistake that think that everything that we have in live is taken for granted. No, it was a very long process. Such thing as discovery of metal. It began with seven important metal in antiquity which is Gold, Copper, Silver, Lead, Tin, Iron and Mercury. In the past, even Iron more expensive than Gold. It has ga around 2,000 years, until another metal discovered in 1250, Arsenic, and Platinum as New World exploration.
Story end, when Iron industry is one of the most polluted industry in the world.