For some reason I'm getting hungrier faster while mining, and I'm finding extra amounts of copper in the copper mountains (yes I know, but usually you'd find some iron as well) - and very little of anythign else. My character is a skilled miner... (light green).
Actually, I think it's that reason. Skilled miners get more stuff from different rocks. It's harder to get gold now to until you reach a certain level if I'm not mistaken.