Bought this game two days ago and have already logged over ten hours, absolutely love it!
One small suggestion is it would be great if mining resource nodes are removed from the map when their charge is depleted. Whenever a mine has used up its resources I usually salvage the mine however I have run into the issue a few times where I place a mine down again thinking I can get more coal or copper when in reality those nodes have all their charges depleted.
Hey there! Ore veins disappear once they are completely depleted. If they stay on the map that means that they can be upgraded to access deeper levels (you can upgrade them in the mine UI, in the upgrade tab, when a mine is placed on top).