A massive gold nugget was reported stolen Thursday from the Long Beach Convention Center, spurring an offer of a $10,000 reward.

Bob Campbell, the owner of a coin shop in Salt Lake City, said he brought the gold nugget to the Long Beach Expo — a show that gathers sellers of coins and other collectibles — to sell for more than $80,000. He said its value exceeds its sheer content in gold, as an “original 49er nugget” believed to date back to the Gold Rush.

“They will lose money if they melt it. It has collector value,” Campbell said. The roughly 27-ounce nugget was about the size of a goose egg, he added, and specimens of that size are “exceedingly rare.”

Video captured by another coin dealer at the event shows someone appearing to press on the display case, then pocket something. Campbell faulted a defect in the case that allowed the thief to wiggle his hand inside.

Long Beach police said they are investing the theft, which was reported before noon Thursday. Campbell is also passing out fliers with a photo of the gold nugget and the alleged thief and personally offering a $10,000 reward hinging on the arrest and conviction of the perpetrator.

“We’re hoping that this information gets out” and maybe “one of his friends will rat him out,” Campbell said.

He urged anyone with information to call his Utah shop at (801) 467-8636 or to contact the Long Beach Police Department regarding case number 24-28245.