Only Vela gets the key to enter the mine. Follow the tracks and grab all the gems. There are tribals below the bridge and on either side of it. Jump over the logs and get the two tribals on the ledge. You'll hit a room with crates. Blast them to get to the elevator switch. Ride the elevator.

Talk to Fish Face. He doesn't say much. Now go through the tunnel, and get 2 tribals by the wooden bridge. Next you find a hiding tribal. Soon you hit the disguise pad. Turn into a tribal. You'll hit two more tribals, down steps, and then another tribal. When you hit Fish Face again, he now thinks you're a tribal and gives you the deflector shield. Heh heh. Use the jetpack to fly back up the elevator, and through the door. Now you can get the remaining three tribals,and head out!

Jet Force Gemini Walkthrough