Three residents of the Xinjiang Uygur autonomous region's Aksu city mistakenly purchased and brought home nuclear waste.
In August 2006, the three men - one of whom is surnamed Liu, while the other two are surnamed Wang - purchased a glittering "treasure" for $2,000 in Kyrgyzstan. They brought it back to Xinjiang, hoping to make a fortune by selling it.
Because they knew nothing about the 274-kg stone, they sliced off a piece to bring to Beijing for expert analysis last January.
Last September, geologists at Tsinghua University concluded it was depleted uranium and called police.
Prosecutors in Aksu decided against arresting the men, because they obviously had no idea what they had purchased. The men have undergone medical examinations and appear to be in good health.