Hall-Héroult aluminum refining discovery (1888)

Simultaneous independent invention by Charles Martin Hall (founder of Alcoa) and Paul Héroult of France, within two months of each other and with no communication. This is the foundational moment for cheap aluminum.

We've made Alclad alloys since the 1930s. Alclad composites have a very thin layer — two to four thousandths of pure aluminum on the surface. Pure aluminum has excellent corrosion resistance and excellent pitting resistance. So if I have an aluminum-copper alloy — this is a piece of something called Novelis Skooter. Novelis is the sheet metal skin off of Alcan, when Alcan merged with Péchiney of France. Two guys invented the refining process in 1888 — and actually last spring in my class one of the students did their presentation on Paul Charles Martin Hall, the founder of Alcoa, and the other was Paul Héroult. Héroult invented the exact same process within two months of Hall, thousands of miles apart, with no communication between them. Refining aluminum, making it cheap.