Earth's core made of iron???

Question

what if it's made of mercury?

It wouldn't explain geodynamo like iron does...

but what's the difference?

Answer 1

there is no difference to be different, its just made of iron, and thats it.

Answer 2

the core is predominantly Iron metal (Fe). It also has a significant amount of the element Nickel (Ni, about 4%) and a light element to make it less dense (about 10% by mass). This light element is either mostly oxygen or sulfur. - That's it!

Answer 3

We can tell what is at the Earth's core because we can "X-ray" it with sound waves from Earth quakes.  And also, the Earth was formed from iron / silicon rocks that stuck together.  Mercury was and is not very common in the  solar system.  It would float to the top of  molten iron, so most all the mercury on  Earth in the crust.