theories about how an enormous diamond
might be found in the centre of gas
Hmmm, because Diamond is still somewhat away from
a closest package, the giant planets may contain a
sort of carbon denser than diamond, metallic
In general, all substances (not only crystalline)
will transform into something with a densest package
of atomic cores and a delocalized electron gas:
metals, if only pressure is high enough.
For hydrogen, some experimental research was/is
done to find this "metallic" form. I remember an article
in SCIAM some years ago.
Of course all this is valid only if temperature is low enough.
(For that reason we speak of planets cores!)
But at the end of pressure scales in neutron stars all materia
transforms to neutrons irrespective of enormous temperatures,
would that be like the iron up here on
the surface or does the pressure
change its structure?
One difference to "surface iron" is obvious: the innermost core is solid, in spite
of the temperature. And one has to be aware that the iron in the core is not
pure, there will be some other metals and carbon in the melt of outer core.
At the border of outer core and mantle sometimes sulfides are assumed.