Hello, just a quick idea.
Maybe there could be a single late-game building in form of a mine, that would have different options for harvesting resources ( coal, stone, sand, iron, ect.) in a neat menu like for picking crops to grow.
If ore runs out just dig more, uncover another vein.
And cost of uncovering this resources could be simmilar to plowing a field.
And, maybe add some small chance for the mine to cave in, so players won’t do just one big infinite mine.
Bye!