Friday, 18 December 2015

‘Finest Opal Ever’ makes World Debut

Billed as the “finest opal ever,” the Virgin Rainbow made its world debut at the South Australian Museum in Adelaide in September as the centerpiece of a larger exhibition to commemorate the centenary of opal mining in Australia.
Veteran miner John Dunstan is credited with discovering the Virgin Rainbow in the desert soil of Coober Pedy in South Australia in 2003.

Dustan has mined opals for 50 years, but the internal fire of the Virgin Rainbow is unlike anything he’s ever seen.

Gibber plain near Coober Pedy
Dustan explained that the Virgin Rainbow is a Belemnite pipe, which is essentially an opal that formed in the skeleton of an extinct ancestor of the common cuttlefish. As Dustan cleaned it off, he realized he made a once-in-a-lifetime discovery.

“I knew it was one of the best ever,” he said. “You’ll never see another piece like that one, it’s so special.
Coober Pedy is often called “The Opal Capital of the World.” The discovery of gem opals sparked a rush of mining activity that has generated top-quality gems for the past 100 years.

Australia produces more than 90% of the world’s precious opals.
Between 100 million and 97 million years ago, Australia’s vast inland sea began retreating. As the sea regressed, a rare episode of acidic weather was taking place, exposing pyrite minerals and releasing sulphuric acid.

As the surface of the basin dried further and cracked, silica-rich gel became trapped in the veins of the rock. Over eons, the silica solidified to form opals
Coober Pedy, an Aboriginal name meaning "White man in a hole", adequately describes the mines and miners' dwellings - burrows dug into the scarp, in order to escape soaring temperatures of the day and the freezing winds at night.