[Mitch]

We all know that the Earth's core is mostly Iron. This explains why we have a magnetic pole in the first place. What is not so clear is whether this Iron has been oxidized to Fe3+ or Fe2+, or whether more strangely it has not been oxidized by O2 and exists as metallic Iron. Current research leads to a metallic Iron core, you can read more about it here: http://www.nature.com/nature/links/040325/040325-6.html

[gregpawin]

What I've always wonder is why isn't the core all liquidy?  I mean maybe I can guess some of the reasons but even still, wouldn't contact with molten rock melt it over time... or wasn't it liquid to begin with?

[jdurg]

What I've always wonder is why isn't the core all liquidy?  I mean maybe I can guess some of the reasons but even still, wouldn't contact with molten rock melt it over time... or wasn't it liquid to begin with?

Well, just think of all the pressure down there in the core of the Earth.  At high pressure, the iron really couldn't exist as a liquid.  The forces acting on it would force the liquid into becoming a solid.  (Kind of like if you compress CO₂ enough, it becomes dry ice).