Opal Mining in Coober PedyOpal Mining in Coober Pedy

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Opal Mining in Coober Pedy

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Attention all opal lovers! If you have found yourself mesmerized by the changing color patterns of this mineraloid, you'll love this course. Do a deep dive into the properties of opals to discover how they are formed and reflect light. Looking to purchase or sell an opal? Learn about different types of opals and how to properly care for them. Every opal enthusiast will learn something new in this course.
Coober Pedy - town sign
Coober Pedy town sign with blower truck. Opal miners use trucks like these. A vacuum sucks debris into the drum. When full, the drum is emptied, forming enormous mounds of dirt next to open shafts. Photo by Graeme Churchard. Licensed under CC By 2.0.

The history of opal mining in Australia is one of danger, regeneration, and success against great odds. As far back as 4,000 BCE, humans have treasured opals and mined them in various locations, such as Kenya and Hungary. However, due to an unlikely combination of geology, fortuitous finds, and the two world wars, Australia has become the world's primary source of opal since the 1880s. In the process, a rich opal-mining culture has risen around its mining fields.

Australian opal - Coober Pedy
Australian opal, 5 cm. Photo by Hannes Grobe. Licensed under CC By-SA 2.5.

Australia produces roughly 95% of the world's precious opal, including black opal. This most valuable variety is found at Lightning Ridge, the largest producer of opal by value. However, the town of Coober Pedy is the largest producer by mass. Coober Pedy's culture is so rooted in opal mining that a mining truck is raised on poles above its town sign.

The Beginnings of Opal Mining in Coober Pedy

Around 1915, a teenage boy whose father was gold prospecting discovered opal in Coober Pedy. Although the first opal claim was staked soon after, it took time before opal mining took off in the area. After WWI, returning soldiers, accustomed to living in trenches, drifted to the opal fields to seek their fortune. After WWII, a wave of Europeans left their war-torn countries to take up opal mining in Australia. As a result, sixty percent of the miners living at Coober Pedy today have Southern or Eastern European ancestry. By the 1970s, the opal rush was in full swing.

The name "Coober Pedy" comes from the Aboriginal Australian kupa piti, meaning "boys' waterhole." However, another type of hole has become quite a hazard. Over the years, miners have dug over 250,000 shafts, making Coober Pedy a dangerous place for tourists to walk around carelessly.

Coober Pedy - warning sign
Sign warning passersby of the danger of falling into mining shafts. Photo © Alan D. Duncan. Used with permission.

The Underground Houses of Coober Pedy

Roughly 1,700 people live in town full-time, working at mining-related jobs. In order to avoid the punishing desert heat, many live in underground houses. Burrowed into hills, these houses require ceilings a minimum of 4 meters high to prevent collapse. Not surprisingly, many homeowners (or home diggers) have found opal while excavating.

Coober Pedy underground home
Underground house in Coober Pedy. Photo by Nachoman-au. Licensed under CC By-SA 3.0.

In the past, grocery stores sold explosives, and homeowners blasted the sides of their houses to find opal. Sometimes, they even blasted into a neighbor's home. Mining in residential areas is now banned. However, many miners get around this loophole by "expanding" their houses to build additional guest rooms.

Coober Pedy - Underground Church
Coober Pedy is also home to underground shops, hotels, and even churches, like the Serbian Orthodox Church of St. Elijah shown here. Photo by Steve Collis. Licensed under CC By 2.0.

Early Mining Methods

For the most part, a small number of miners worked together on opal-mining ventures, rather than large corporations. The earliest miners dug their 3 to 10-meter shafts by hand. In order to prevent the dusty, sun-baked soil from collapsing, they reinforced the walls with timber. They lowered themselves into the shafts with windlasses, then removed the waste soil or mullock via buckets lifted by the windlasses. Miners dug tunnels the old-fashioned way, with shovels, pickaxes, and sometimes with homemade explosives buried in pockets of soil.

With any luck, miners found veins of common opal that twisted and turned throughout the rocks. They followed these veins in hopes that some might become precious opal. More often than not, the veins either disappeared or plunged into untraceable depths.

Coober Pedy - Australian opal veins
Blue-green opal veins in ferruginous (iron-rich) rock from Australia, from the collection of the Natural History Museum, London, UK. Photo by Aramgutang. Public Domain.

Occasionally, miners discovered the opalized fossils of prehistoric animals or plants. Over millions of years, these remains had turned into opal material.

Coober Pedy - opalized bivalve fossil
Opalized bivalve found in Coober Pedy. Photo by James St. John. Licensed under CC By 2.0.

Modern Mining Methods

Beginning in the 1970s, mechanized opal mining became prevalent. It usually involves advanced equipment such as Calweld drills for shaft digging and tunneling machines or front-end loaders for horizontal tunneling.

Coober Pedy - Calweld drill
Miners use Calweld drills like this one for digging shafts. "Calweld 150-H" by hitchster. Licensed under CC By 2.0.

Automatic bucket tippers or gigantic pipe vacuums transport the mullock excavated by machine or explosives. This soil is then either transported to a drum mounted on a truck (like the one atop the Coober Pedy town sign) to be emptied later or shot out by the vacuum into a pile close to the shaft.

Coober Pedy - blower truck
Blower used for mining opal at Coober Pedy. Photo by Bushie. Licensed under CC By 2.0.

Supposedly, an experienced miner can tell from the sound of the vacuum when opal has been found. If miners find precious opal, they must extract it very carefully, since it can be quite fragile.

Coober Pedy - dirt mounds
Mounds of dirt removed from tunnels at Coober Pedy. Photo by Robyn Jay. Licensed under CC By-SA 2.0.

Deciding How to Mine for Opals

Mining always involves assessing investment versus payoff. Some solitary miners choose to start their enterprises small. For example, they lower themselves down abandoned mine shafts using cable cranks or rope ladders attached to their trucks.

In contrast, miners who choose to use advanced methods can dig quickly. They can also dig test shafts before committing to excavating large areas. These miners will sometimes use bulldozers to remove surface layers of dirt, while workers on the side watch for traces of opal and check opal veins for precious material. Other options include jackhammers and dynamite.

Of course, the more advanced the method, the higher the cost and greater the risk of damaging potential opal veins.

Coober Pedy - tunnel boring machine, Bochum Museum
Tunnel boring machine with revolving head for digging horizontal tunnels. "Tunnel boring machine KTF 280 (2008)," in the German Mining Museum, Bochum, Germany. Photo by Jochen Teufel. Licensed under CC By-SA 3.0.

The Hazards of Opal Mining

Opal mining is a dangerous venture, especially for those working alone. Tunnels often don't have enough oxygen, and cave-ins may occur. Sudden storms can also flood them. Workers face extreme heat above ground and claustrophobia below ground. Furthermore, opals occur hidden in veins, pipes, or kernels within rock. Thus, miners can never tell where opal is to be found until they start digging.

The first opal discoveries in Australia were serendipitous. For example, a horse kicked up a lump of opal, or a teenager picked some sparkly stones off the ground. Miners then dug close to these locations. Of the opal found today, 95% is worthless gray, white potch, or common opal without phenomenal properties like play of color.

Personalities and Dreams

Australia's opal fields abound with stories of spectacular finds and eccentric characters. Many miners left their past lives to seek peace (and opals) in Coober Pedy's stark terrain. Some had hectic professional careers. Others had a head start on eccentricity. For example, the colorful home of "Crocodile Harry," one of Coober Pedy's must-see tourist destinations, belonged to a former crocodile hunter and self-declared Latvian baron in hiding.

Coober Pedy - Crocodile Harry's
An example of the decor at Crocodile Harry's. "Croc Harry's Art.." by Ben Copper. Licensed under CC By-ND 2.0.

Of course, here you'll also find the average miners who dream that the next foot of ground will yield an opal that will make them millionaires. For most, hoping for this jackpot keeps them underground, searching with flashlights for a gleam of color. Sometimes, they're richly rewarded.

Examples of Coober Pedy Opal

Coober Pedy - Olympic Australis opal
This 3.5 kg beauty, the Olympic Australis opal, was found 10 meters below the surface at Coober Pedy. It's the most expensive opal in the world. © Opal Auctions. Used with permission.
Coober Pedy - white opal on matrix
White opal with matrix found at Coober Pedy. Photo by Dpulitzer. Licensed under CC By-SA 3.0.
Coober Pedy opals - Denver Museum of Nature and Science
Precious opal from Coober Pedy, on display at the Denver Museum of Nature & Science, Denver, Colorado. Photo by James St. John. Licensed under CC By 2.0.

Phoebe Shang, GG

A gem lover and writer, Phoebe holds a graduate gemologist degree from the Gemological Institute of America and masters in writing from Columbia University. She got her start in gemology translating and editing Colored Stone and Mineral Highlights for a professor based in Shanghai. Whether in LA, Taipei, or New York, Phoebe spends her time searching for gems to design and being lost in good books.

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