Mines of Mercury

The Mines of Mercury were a location in Tom Paris' holodeck program The Adventures of Captain Proton, worked by slaves of Doctor Chaotica. As a nod to the practice of re-using sets in the 1930s serials Captain Proton was emulating, Mercury looked almost identical to the later-featured Planet X, though unlike Planet X, it had an erupting volcano. 

When Chaotica was about to conquer Earth in the final chapter, he threatened to send all Earthlings that did not cooperate to the mines.