Aluminum forms very strong chemical bonds, so it's difficult to reduce it to its base form. Aluminum oxide is one of the most chemically stable materials there

Aluminum forms very strong chemical bonds, so it's difficult to reduce it to its base form. Aluminum oxide is one of the most chemically stable materials there is. In WWII, being able to effectively refine aluminum (using lots of hydroelectric power in the Pacific Northwest) was one of the key economic factors that lead to an Allied victory. For the entire commercial history of aluminum, it's been produced through molten-salt electrolysis (the Hall-Heroult process).