Ok mines are really hard to build, everyone is aware of that. There is no direct problem with that except that it gives an overwhelming advantage to the few that manage to get one. What I am suggesting is that there should be an alternate method to gather ore. The aim is not to replace mines, the ore found may in general be lower quality and the collection is SLOW. This should help small community get the essential goods like a cauldron or a tankyard without having to give an arm and a leg to someone else.
I- Gathering ore/ metals by using sluice box in water.
This method is very slow but has some chance to yield small quantity of metal. You need to build a sluice box and use it in any low water spot.
II-Gathering ore by surface prospection.
Walk around and dig with a pick. You will find some ore with some luck. Some spots might yield more than others, like mountains.
III-Iron sands
Patch of iron sand that can be processed for a low metal yield.