Right, I'm sure, other than just the Bottleneckers, there're a few others who have seen their mines start to wall off invisibly and their ore run out, leaving their settlement ( before founded on ore ) start to become slightly useless.
Now, my suggestion is not to make mines completely unlimited but to instead slowly increase the size of mines over time. The idea is that, as time passes, new veins of ore in the mine become uncovered, allowing us to build a new shaft in the mine and expand it, getting that ore before the shaft becomes useless. The time between uncovering of shafts should probably be ( where T = time taken for the shaft to be cleared out ) T+1/4(T), to make it still viable to stay in the town, but without having an unlimited amount of ore. You would also still have the initial "rush" of ore when you enter a new mine, but it would prevent people from having the same amount of ore constantly.
Also, there should probably be dangers introduced in this system, such as uncovering temples devoted to dark gods ( C'THULHU ), waking demons, cave ins, giant cave spiders ( the worst out of all of these, in my opinion ) etc. These things should also take up the normal "shaft" slot, as a way of not allowing players to CONSTANTLY have their own way, with an element of randomness introduced. Rewards could, of course, also be given from these dangerous events, but are not completely needed.