$16-Million Worth of Mexican Silver Still Buried in Southern Virginia?

Following the surrender of Robert E. Lee, the authors tell us, there remained some gold and "39 kegs of Mexican silver dollars" in the Confederate treasury.In an article for History News Network they explained that these "were coins that the Confederacy received through the sale of cotton to Mexico. The Mexican coins had been transported to Danville, Virginia," as Confederacy President Jefferson Davis and his entourage fled south. The 9,000 pounds of silver became burdensome. "For this reason," the authors say, "the coins were almost certainly buried in Danville, and evidence suggests, they remain there today."
There is much more to the book than just the treasure tale; it chronicles a clandestine effort to keep the Confederacy alive despite the military defeat. But for those of us following the price of silver and its effect on coin collecting, those kegs of Mexican reales provide intriguing points to ponder. For instance, if the book was published in 2008 then it was written even earlier -- is $16-million still a valid guess at the value?