Mining investors and mine guys might find this piece from The Australian interesting. It's called, "New profits in old mines" and it talks about miners developing old, existing mines rather than exploring for new ones. Quote from the article:
many of our companies are going back to old prospects and old mines, and find it easier to revive them by drilling deeper and wider than getting bogged down by the long lead times involved in finding and developing new discoveries.
In other words, brownfield is cheaper than greenfield and it sure helps a lot to have files of old drilling records to get you started.
Check it out!