Apparently I was posting at the same time as Stonetone. I have to say that I'm not sure what the natural vs man-made comparison means. Just because something has been "man-made" doesn't make it bad, again, since we are talking about this subjective "tone" thing. Are you saying that the atoms in the granite are more free to vibrate since they haven't been melted down and put under pressure? Granite was formed by millions of years of high pressure. I will give you that heating and forming metals does change their molecular structure, that's why it's hard to control dimensions tightly on weldments, the metal tends to stress relieve in the areas that get heated from the welding process. But again, my take is that I can see the benefits of using a larger granite or machined brass trem block over the standard thin steel ones, especially the pot metal ones that are on a lot of trems out there. But what about a larger machined steel block, my "instinct" tells me that would also increase sustain, although steel would likely make the tone brighter, but I can't give you a scientific explanation why without research, and I have enough work that I should be doing right now on my plate that I don't have time for that kind of research.
I will say that probably the best thing you can do to improve your tone, assuming that you have a good basic setup (guitar, amp, etc...) is to practice. Pups, blocks, strings, etc... are small incremental improvements, none of them will be life changing unless of course you are playing single coils, in which case you really need to install humbucker (just kidding!!!! : popworm: ).
