[sbierwagen]

>the purity needed for the silicon used in processors was absurdly high

Yes. Silicon wafers are cut from a monocrystalline boule, a single flawless silicon crystal with no defects or inclusions. A big chunk of silicon atoms, nothing else at all. (Doping happens later) To the extent any physical object can be called "perfect", a semiconductor wafer is perfect.

(Of course after manufacturing it will start picking up embedded hydrogen and helium atoms from cosmic rays and alpha particle background radiation.)