I started to think that excavations are waste of time too. I have 7000 discovery rate. A couple of days ago, i could find beldum, timburr, pawniard and so forth, but now, they never show up. There must be a bug. Additionally, especially in natural site, when i smash a rock, some other rocks are being smashed by themselves too. I hope admins fix this problem. Otherwise, it's just a time and money wasting quest, nothing more.