Hollywood Reporter is reporting that Michael Mann is circling GOLD, a thriller surrounding a search for the titular metal, which is being described as thematically along the lines of THE TREASURE OF SIERRA MADRE (and really, that film's probably the template for this kind of thing anyway). Mann would produce with Paul Haggis and Michael Nozik.
Apparently Haggis flipped over a spec written by Patrick Massett and John Zinman (writers of television's FRIDAY NIGHT LIGHTS and CHICAGO CODE), but too busy to sit in the director's chair himself, showed the project to Mann, who is presently eyeing it as a film for himself to direct. Mann's attached to a few projects himself, so it's not certain whether or not this would be his follow-up to PUBLIC ENEMIES or something for him to do down the road. The film is still in early development.
I'd be curious to know if this is in modern day or not. A modern day gold hunt would be interesting, considering that we've seen many stories about the gold rush and gold hunts in yesteryear but not much of recent events. The premise is vague enough that it could be about a mining operation or a simple heist film. Either way, with Michael Mann directing, if this film happens it would probably not be an intimate film, but something wider in scope.