Unexpected places to find wealth.

TOKYO (Reuters) - Resource-poor Japan just discovered a new source of mineral wealth -- sewage.

A sewage treatment facility in central Japan has recorded a higher gold yield from sludge than can be found at some of the world's best mines. An official in Nagano prefecture, northwest of Tokyo, said the high percentage of gold found at the Suwa facility was probably due to the large number of precision equipment manufacturers in the vicinity that use the yellow metal. The facility recently recorded finding 1,890 grammes of gold per tonne of ash from incinerated sludge.

That is a far higher gold content than Japan's Hishikari Mine, one of the world's top gold mines, owned by Sumitomo Metal Mining Co Ltd, which contains 20-40 grammes of the precious metal per tonne of ore.

The prefecture is so far due to receive 5 million yen ($55,810) for the gold, minus expenses.

It expects to earn about 15 million yen for the fiscal year to the end of March from the gold it has retrieved from the ashes of incinerated sludge.

"How much we actually receive will depend on gold prices at the time," the official said.