NEVADA CITY, CA (AP).- A 6.2-pound hunk of gold was auctioned for nearly half a million dollars in March after a man claimed he found it on his Sierra Nevada property, but it turns out it was actually dug up decades earlier in Australia.

After Jim Sanders' "find" on his property near Nevada City in California's Gold Country made news last year, Australian prospector Murray Cox compared pictures of Sanders' "Washington Nugget" with "The Orange Roughie" he unearthed near Melbourne in 1987, the San Francisco Chronicle reported.

They were an exact match, except the Washington Nugget sold for $460,000 in March and Cox originally sold it for $50,000.

Cox contacted Don Kagin, a coin dealer, and mining geologist Fred Holabird, who together auctioned the nugget for Sanders. The two investigated Cox's claims and determined he was right.

"The parties have mutually concluded that the nugget was from Australia," Holabird said Tuesday in a statement.

As for how Sanders got his hands on the Aussie gold chunk? The dealers said confidentiality agreements barred them from elaborating.

Cox told the Chronicle that he sold the Orange Rougie in 1989 and is not sure how it wound up with Sanders.

The person who bought the gold in March has been reimbursed, and the nugget sold for a smaller price to another bidder.

Despite duping people as to the nugget's origin, Kagin said everyone involved has agreed that fraud charges against Sanders are unnecessary.

"The whole matter has been concluded to everyone's satisfaction," he said.

The unusual gold chunk fetched $460,000 at auction because it was believed to be the largest California nugget left in existence.

While details of the 98.6-ounce nugget's new sale price were not available, gold closed at $1,529.20 an ounce Wednesday.

Copyright 2011 The Associated Press.