The rare stone thing would be better for nuclear power. Find lots of rare stone, put it together in a huge pile, they get warm and cause mysterious diseases.
Uranium is actually pretty common, refining out the right isotope is the complicated part. Heck there were a couple natural nuclear reactors in a place that generated power for a few million years.
Silicon is just the base material. The whole process involves a whole bunch of other chemicals, and some of those are made of much rarer stuff than silicon.
Sure, Silicon works as a cheap base. Boron, phosphorus, arsenic and antimony are also used in the process, though. Other elements are also finding use in the process.
There is also a minor error in the middle about the 'sigils'. When scribing process is happening, the other elements are embedded into or deposited onto the substrate between 'scribings'.
The form of silicon used in semiconductor manufacturing, specific formations of sand, is becoming harder to source from the environment. Silicon the element is incredibly abundant - the vast majority of all rocks on Earth are silicates - so there isn't a risk that we run out of silicon itself any time soon.
What may happen, in several decades, is an increase in price due to the need to process more abundant rocks to obtain pure silicon.