Check out the newest addition to the Cox Nature Exchange, the Hardesty Gem Dig, a hands-on activity that gives guests a new way to learn about geology, mining and archeology. Diggers can get their hands dirty by excavating their own treasures, like polished gems and minerals, in a large structure filled with special san and that's modeled after real dig sites. Whatever loot is uncovered gets to go home with the digger in a special treasure bag. Or, trade them for other cool nature things at the Nature Exchange at the Zoo. At the Tulsa Zoo, geology rocks! Pun totally intended. Cost is $3 for guests, $2 for Zoo Friends members.