[gentle music]

Chemistry is about the number of electrons in the outer shell of an atom.

Physics is about the nucleus of the atom, the protons and the neutrons at the center.

So when you try and separate materials through chemistry, you're worried about how many electrons are whizzing around in that outer shell.

The problem with rare earths is they all have the same number of electrons in that outer shell, but they have different number of neutrons and protons in the nucleus of, and different numbers of electrons in inner shells.

This means you can't use chemistry to separate.

Kind of inefficient if you're after one thing.

Yes.