There's more aluminium than iron in the Earth’s crust but iron was used extensively long before aluminium why

Answer 1

Because to extract usable aluminum, you need massive amounts of electrical current. It was not readily available in the iron age.

Answer 2

Iron is easier to extract from iron ore. You simply need to heat it until the iron melts and comes out . Aluminum on the other hand oxidizes when heated so the pure metal never comes out of the bauxite, it simply forms more bauxite. The way to extract aluminum from its ore involves running a large electrical current through the ore, which separates the aluminum atoms from the oxygen atoms, the oxygen gas created is drawn out, leaving the pure aluminum behind. The aluminum can then be melted in the absence of air and formed.
Before this process was invented in the late 1800s, small amounts of aluminum could be extracted from ore by smelting, but not enough to be used( through most of history, it was more costly than gold).

Answer 3

Two reasons: the first has already been answered (the processing answers), and the second is that aluminum is not just more common than iron in the crust it is also more widely disseminated and not concentrated in ore bodies as is iron (and most other economic metals). So, it is more difficult to find large amounts of aluminum in any one place.

Answer 4

Naturally occurring aluminum is generally the oxidized alumina, Al2O3. Methods for isolating metallic aluminum were not developed until 1827 and even then were very expensive.