Are the gold bars in Fort Knox really made of the precious metal? Or has the U.S. government secretly sold off the nation's stockpile and replaced it with metal bars that are only painted gold? Ron Paul wants to find out. Giving legitimacy to an Internet conspiracy theory that the gold in Fort Knox is fake, the iconoclast Republican congressman from Texas has asked adminstration officials to audit the purity of the nation's 700,000 gold bars held in Fort Knox, according to an internal Treasury document obtained by CNBC. Paul, ... who chairs the House's subcommittee on Domestic Monetary Policy, had previously called for the U.S. gold reserve to be counted and for a return to the gold standard. He now appears to be going a step further. One conspiracy theory says that no one has actually seen the gold since the 1930s. But in a letter to Paul in September, the Treasury Inspector General said he had personally observed the gold reserves located in each of the deep storage compartments." CNBC asked for a tour of Fort Knox to film the gold. An official at the Mint told us that not he was not aware that any member of Congress had toured the facility since [1974]. Fort Knox is "a closed facility," the official said. And so the conspiracy theory continues...