Which metal is most abundant in Earth's crust?

Aluminium is the most plentiful metal in Earth crust, accounting for roughly 8% of its mass — and the third most abundant element overall, behind oxygen and silicon. Despite its abundance, pure aluminium was once so hard to extract that it was more valuable than gold in the 19th century. That changed in 1886 when the Hall-Heroult electrolysis process made mass production possible. Iron is the second most abundant metal in the crust at about 5%, and is the most abundant metal in Earth as a whole because it dominates the planet core.