Discovered in 1827 by Friedrich Wöhler, aluminum, though the most common metal on earth, is always found tightly locked in compounds. Efforts to use electrolysis to reduce it failed repeatedly, and for years it remained an exotic metal used in jewelry and for such special purposes as capping the Washington Monument.
The problem many researchers had with extracting aluminum was that electrolysis of an aluminum salt dissolved in water yields aluminum hydroxide. Both Hall and Héroult avoided this problem by dissolving aluminum oxide in a new solvent-fused cryolite, Na3AlF6.
With the new aluminum electrolytic reduction process, called the Hall-Héroult process, the price of aluminum dropped dramatically. Developments in the early 1880s had reduced the price of a pound of aluminum from 12 dollars to 4 dollars a pound. The Hall-Héroult process reduced it to 2 dollars a pound, then again to 30 cents.