BENTONVILLE, Ark.—The proprietor of a metal recycling business was suspicious of the group of young people who wanted to sell him a 62.5-pound chunk of metal, so he convinced them it was only lead and gave them $30 for it.

It was really a silver ingot—worth $15,000. And the metals dealer called police.

Police Detective Mike Stegall said six people have been arrested on a variety of charges alleging they stole two safes containing the ingot, gold and silver coins worth about $25,000, and a rare D.H. Lawrence first-edition book with an estimated value of $5,000.

“They’re kids, they had no idea what they had,” Stegall said.

A businessman reported the items stolen in August. Police said most of the items have been recovered but the rare book is still missing.

An arrest affidavit said the defendants agreed to $30 for the ingot because they needed money for gas.