SYDNEY.- An Australian museum said Monday it would exhibit what it believes is the best opal stone ever found -- a 6.0-centimetre (2.4 inch) multi-coloured gem unearthed in the Outback named the Virgin Rainbow.

The South Australian Museum said the stone, valued at more than Aus$1.0 million (US$730,000), would go on public display for the first time in September to mark the centenary of opal mining in the country.  

"It's of unequalled quality, it's a fully crystal opal," museum director Brian Oldman told AFP.

"It's almost as if there's a fire in there; you see all different colours. As the light changes, the opal itself changes. It's quite an amazing trick of nature."

Dug up in the South Australia desert town of Coober Pedy in 2003 by local miners, the Virgin Rainbow came into the museum's possession about 18 months ago and will be part of an exhibition opening in Adelaide next month.

Some 90 percent of the world's opals come from South Australia, once covered by an inland sea which over millions of years provided an ideal environment for the formation of the stone.

"I think this exhibition will have the finest collection of precious opals that we believe have been brought to one place in the world," Oldman added.

Opals were first discovered at Coober Pedy -- widely-known as the opal capital of the world --  in 1914 by a boy named Willie Hutchison who was on a gold mining expedition with his father.  

"The story goes that Willie set out in search for water one day, rather than staying at camp as he'd been instructed to do by his father," Oldman said. "He came back to camp with water, but also with precious opal gemstones."



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