Gold bars are pictured at the Austrian Gold and Silver Separating Plant "Oegussa" in Vienna, Aug. 26, 2011. Reuters

A giant gold nugget found on public land over the summer was expected to sell for $350,000 at the San Francisco Fall Antiques Show this week. The six-pound so-called "Butte Nugget" was found by a gold hunter in the Butte County mountains and has lured hundreds of spectators to the upscale antiques show.

The gold was being sold by Don Kagin on behalf of the anonymous owner who found it in July on public land, according to the Los Angeles Times. Kagin is president of Kagin’s Inc., a numismatic company that specializes in U.S. gold coins. Kagin is also the seller of the $10 million in gold coins found last year by a Saddle Ridge couple and their dog. Gold prospecting is legal under federal law.

It's been years since a piece of gold that large has been found in California’s historic Gold Country. Giant gold nuggets were the norm all over the Sierra in the mid-1800s, including the 54-pound Magalia Nugget found in 1859. But most were sold off in chunks, according to the San Francisco Gate.

“What we have here is probably the largest gold nugget from California in private hands today,” precious metals specialist David McCarthy said. “I didn’t expect to a California nugget of this size come out of the ground in my lifetime.”

McCarthy said the nugget is millions of years old. “Some sort of action of water actually crushed this down,” he said.

McCarthy said there had been four prospective buyers for the nugget. One woman stopped by the antiques show, but no money was exchanged. “There’s gold and then there’s gold,” the woman, who declined to give her name, said. “But there is nothing like that nugget anywhere. Nice piece.”