A script? Nah... common event will do it fine, you just need to use a variable.
One way: You could make the mine a two page event. The first page would be the harvest page, and after you do all the harvesting stuff, all you need to do is turn on a switch (let's call it Switch X). The second page would be conditioned on Switch X and would be blank or say this mine is not ready for harvesting or something.
Then you would make the common event, also conditioned on Switch X, like this:
Wait: 60 Frames
Variable Y: Mine Timer += 1
Conditional Branch: Variable Y == 60
Switch X = OFF
Variable Y = 0
Branch End
That should work across maps, and that's just one way you could do it off the top of my head. I am sure there are probably better ways.