David McCarthy, a coin and rare-minerals expert, told the Chronicle that he took a blindfolded ride to the site of the discovery so he would be satisfied the nugget was genuine. The finder of the Butte Nugget used a metal detector and told colleagues he initially thought he had come across a pipe or some other "big piece of trash" underground, part-time local prospector Bob Van Camp told the Chico Enterprise-Record (http://bit.ly/1sQwT04 ). Worried that the strong reading on the metal detector would mask any signal from surrounding gold nuggets, the man decided to dig it up, said Van Camp, who filmed himself briefly holding the Butte Nugget.