Coober Pedy Opals — The World's Largest Opal Field

Coober Pedy is a remote mining town in northern South Australia, roughly 850 km north of Adelaide on the Stuart Highway, approximately midway between Adelaide and Alice Springs. For more than a century it has been the world's largest producer of precious opal by volume, and the principal source of light opal and crystal opal. It is also where the Christianos family began mining in 1956 — the field that started three generations of our business.

Location: Northern South Australia, on the Stuart Highway between Adelaide and Alice Springs
Distance from Adelaide: ~850 km north
Main product: Light opal (body tone N7–N9) and crystal opal; some darker stones
Opal first found: 1915
Town name: From Aboriginal kupa piti, often translated as “white man's hole” — a reference to the early miners' underground dwellings
Notable diggings: Eight Mile, Shell Patch, Olympic, Ten Mile and others

Why Coober Pedy produces light and crystal opal

The body tone of a precious opal — the underlying darkness on which the play-of-colour sits — reflects the rock around it as the opal formed. Coober Pedy opal forms in pale Cretaceous-aged sandstone and claystone host rock. Because the host is light-coloured, the opal that grew within it carries a light base, typically N7–N9 on the body-tone scale. The same geology that produces black opal at Lightning Ridge — carbonaceous, dark claystone — simply isn't present at Coober Pedy.

Where Coober Pedy excels is in crystal opal: precious opal that is transparent or semi-transparent through its body, so the play-of-colour appears throughout the stone rather than only on the surface. High-clarity crystal opal from Coober Pedy is one of the most three-dimensional gems in the precious-stone world, and the field has supplied the bulk of the world's crystal opal for decades.

For more on how body tone is judged and how it relates to clarity, see our body tone guide (N1–N9) and our types of Australian opal guide.

A short history

Precious opal was first found at Coober Pedy in 1915, by a young prospector accompanying a gold-search party that had stopped near a low rise of hills. Within a few years the strike attracted prospectors from across Australia. The early diggings spread outward from that first find, and over the following decades the field grew to cover hundreds of square kilometres of desert country.

Two facts shaped the town that grew up around the diggings. The first is the climate: summer surface temperatures regularly exceed 40 °C, and the wind-blown gibber plains offer no natural shelter. The second is the soft host rock, which can be excavated with hand tools or light machinery. The combination produced the dugout — the underground home cut into the side of a low hill, naturally insulated at a steady ~22 °C year-round. Today many of Coober Pedy's houses, churches, hotels and museums are still underground.

The town's Aboriginal-language name kupa piti is usually translated as “white man's hole” or “boys' waterhole” depending on the source. By either reading, the reference is to the holes the miners dug.

Diggings around Coober Pedy

The Coober Pedy field is spread across hundreds of square kilometres of desert country, divided into a long list of named diggings. Many take their name from the mile marker on the road out from town — in practice, almost every mile marker has its own diggings, and that's before counting the many other named patches that don't follow the mile-marker scheme. A few of the better-known examples:

Eight Mile Diggings
Shell Patch Diggings
Olympic Diggings
Ten Mile Diggings

Many smaller and historic diggings carry working names that are best known to local miners and the long-term Coober Pedy community. When the specific origin of one of our stones is known and recorded, it is shown alongside the item in the catalogue. See the classification reference for the full list of mining-origin codes we use.

What makes Coober Pedy stones distinctive

Outstanding clarity. The light host produces a high proportion of clean, transparent crystal opal — rarer at any other major field.
Soft, pastel bases. Even the more opaque stones tend toward soft, milky-light backgrounds that show pinfire and broad-flash patterns gently rather than dramatically.
Large stones. Coober Pedy seams have historically produced some of the world's largest precious-opal specimens. Carat weights that would be exceptional at Lightning Ridge are workable here.
Excellent rough for cabbing. Much of the Coober Pedy yield is sold as rough to cutters in Australia and overseas; the field has trained generations of opal cutters in light-opal technique.

How the opal is mined

Coober Pedy mining is largely shaft-and-tunnel, like Lightning Ridge, but the field is famous for its mechanised extraction. A vertical shaft is sunk to the “level” where the opal-bearing seam runs. The dirt is then brought to the surface, and Coober Pedy operations characteristically use:

Blower trucks — large purpose-built vacuum trucks that lower a flexible hose down the shaft and suck the broken dirt up to a holding hopper on the truck. The blower truck is, in many ways, the Coober Pedy invention; visitors to the field often see them at work.
Tunnelling machines — small underground digging equipment that drives along the level.
Bulldozers and open-cut machinery on larger runs, where the seam is shallow enough to be worked from the surface, where there may be several levels all carrying opal, or where it is too dangerous to work underground.

Coober Pedy mining differs from Lightning Ridge in one important way: at Coober Pedy, the extracted opal dirt is almost never washed. After the seam is loosened and removed — historically by hand, today mostly by tunnelling machine — the dirt is sorted dry rather than put through a water wash. The traditional method was to spread the dirt and search through it by hand. Today most operations run the dirt through a noodling machine: a conveyor belt that passes through an enclosed room lit by ultraviolet light. The light-bodied Coober Pedy opal fluoresces under UV, and pickers sitting either side of the belt spot the stones as they pass and pick them off by hand.

Christianos Opals at Coober Pedy

Christianos Opals began at Coober Pedy in 1956, when our grandfather George Christianos Sr. started mining there. The field was the foundation of three generations of the family business. Around 1977 Emmanuel (second generation) moved the operation to Mintabie, and in the late 1980's and early 90's extended to Lambina, and at points back to Coober Pedy itself. In 2009 George Emmanuel (third generation) moved the business to Lightning Ridge in pursuit of black opal at source.

The Coober Pedy years gave us the experience and the supply network that we still draw on. A meaningful share of the light and crystal opal in our current inventory traces back, directly or indirectly, to Coober Pedy and its sister South Australian fields.

Visiting Coober Pedy

Coober Pedy is a working mining town that has also become one of South Australia's most distinctive tourist destinations. It sits on the Stuart Highway midway between Adelaide and Alice Springs, with regular long-distance bus and small-aircraft services. Notable attractions for visitors include:

The Serbian Orthodox Church, cut entirely underground.
Several underground hotels and B&Bs — an experience available almost nowhere else in the world.
The Old Timers Mine museum, a preserved historic dugout and working mine.
The Big Winch lookout, overlooking the mullock-dotted desert.
Public “noodling” areas, where visitors can fossick through old tailings and (occasionally) find a small stone of their own.