I’m not sure why I haven’t done this until now… but I have a world class library at my fingertips and I don’t use it for a lot of tea related things, such as looking at Yixing books. There are some, such as the MAI foundation book, that are more commonly found, and there are others that are rarer or harder to get unless you’re in China. So, I checked out a few and intend to flip through them — all in the name of procrastinating on my real work.
So, for example, I re-read the little bit about particle size in Yixing pots over time — how modern day clay have much finer particles than earlier ones, and that firing temperature has also gone up, resulting in denser products that will have a higher pitched sound when knocked and also a finer surface. Comparartively, the earlier pots will be duller and sound more hollow. Seems to jive with what I have seen in person.