I found the corresponding bug report in flyspray turns into some animated discussion. As it is worth discussing, maybe the discussion should take place in the forums....
1) Should minerals be visible or have some effect to show where they are?
2) is the same thing good for harvesting, as it is?
2a) in case of harvesting (and gems): are the respawn rates too high?
3) How about the idea to make a spell to find minerals or plants or...
I think: don't make fast changes. For me, one of the basic things in ps is the necessity to communicate. So, if you want to find iron, and cannot find it on your own, that is good. Go and ask your fellow players!
My favorite scenario (mining and harvesting) would be moving (depleted and freshly discovered) sites. Depending on experience, one can find new resources (marks for resources visible depending on mining or harvesting rank). In this scenario, a higher grade spell (brown?) would make sense to allow mages into the resource finding business. This scenario would enhance the need for communication, and thus would be in tune with the (for me primary) branding feature of ps.
As always, this depends on my personal interpretation of what ps is about, and may be wide off the mark for others