There is a story/myth whose earliest retelling is from Petronius about that a gold or metal worker who devised a wondrous new metal and after confirming he was the only one who knew its secret was put to death to avoid upsetting the economy. It has been thought this may have been an aluminium alloy.

That seems unlikely - unless it somehow avoided making pure aluminium first, its notoriously difficult (and quite dirty) even by modern standards to rerine aluminium, due to how strong bond aluminium compounds form (which is alsow what protects aluminium from the elements once you have it - a quickly forming thin layer of aluminium oxide).