Mines shouldn't be infinite in my opinion. Putting a limit on the number of resources you can mine from one mine, forces you to branch out to other mines in the world and gives a feeling of exploration.
Another option is to have it be finite, but then have it generate back over time. Will require designers playtesting but I think in its current state, it is a bit too OP. Personally think, for the beginning of the game, its fine but late game it becomes OP.