A little update on the situation: First, thanks for the confirmation that it's just unlucky RNG. I'm up to 7 of them now, completely excavated at least 8 hits deep, and I have managed to find 1 chest and a couple jemstones along with more skeletal remains. I just got my first pickax after defeating the elkthyr boss- I dont even know what these wishbones and stagbreakers that are being talked about are. I'll look 'em up though. Thanks everyone.