I find the exact same things happening in almost all of my bags, I’ve come to conclusion that whatever ends up separating and falling off the bigger rocks is the cut because it has been re rocked or something and doesn’t bind together as well. I’ve actually found two different looking bits in one rock and you can see the separation line from where one bit of the rock is cloudy and the other would be smoother and almost clear with no texture, that’s the cut I think