They're already in there.
Within Pathfinder 1e there is such a thing as Special Raw Materials which seems to fall under what you're asking. Essentially, these are improved materials, but they only affect how items are crafted, rather than the item that is produced, but that's okay.
Such a thing isn't really something there should be general rules for in the first place. If there was a general way to refine a (special) material so it had different properties than the base material did, it should simply be listed as another special material than a refinement method. That's why we have Steel, Pyre Steel, Frost-Forged Steel, Fire-Forged Steel, Nexavaran Steel, etc. as materials you can use.
This also correlates to my experience as an engineer when designing new products. You don't simply ask for steel, you need to specify whether you're getting low-carbon, galvanized, nickel-plated, stainless, etc, and even then you need to specify the range of alloys you're able to use.
How a material has been refined and processed is what determines what material it is. Thus, the answer to your question is that information on improved special materials along with the refinement of them already exists. You just want more details on the processes they go through to produce them, which is not something you're likely to find outside of vague generic flavor text or a materials science textbook.