An Introduction to Raw Australian Opal

An Introduction to Raw Australian Opal

Posted by Therese Evert on 6th Jul 2022

Raw Australian opal is a rare and valuable resource. 

Australia produces 95% of world opal. 

Raw Australian opal is prized for its beauty, diversity, and stability. 

Opal is also found in Eastern Europe, Africa, Mexico, Indonesia, (albeit in smaller quantities) with the earliest recordings of the existence of opal dating back to the Romans. In the  Natural History of the World published in 77AD, Pliny the Elder writes that opal is the most highly prized and valued gemstone in all the Empire. 

Indeed, Pliny was an enthusiast who, although from a completely different time, was not unlike the opal “hunters” in the opal mining reality TV show Outback Opal Hunters, on the Discovery Channel. 

It’s been proven time, and time, again that once opal turns your head there’s no turning back.

An Introduction to Raw Australian Opal 

1. No two opals are the same. 

2. History and the opal industry in the modern era 

3. Opal miners 

4. Camp Life 

5. Camp Communication 

6. Opal Formation 

7. Precious opal and Common opal 

8. Where is raw opal found? 

9. The opal industry in the current time 

10. Author Bio and references

1. No two opals are the same 

It’s said that an opal finds its owner. 

As  opal cutters and sellers for over 40 years we have sold thousands, if not millions, of opals. During our time in retail, we often witnessed opals “talking” to their prospective owners. 

Countless times we have witnessed people gravitate towards a particular opal and no matter how much they look around for something else, that takes their fancy, they always come back to the one that “spoke” to them in the first place. 

There are opal miners who find it difficult to sell an opal they’ve fallen in love with. No matter how much they might need to sell the opal, they hold off for as long as possible. Even then, after a deal has been done, I’ve heard of miners who have been struck with instant remorse and sought out the buyer to buy the opal back.

2. History and the opal industry in the modern era

The Australian Opal Industry is a boutique industry open to anyone who’s willing to have a go. There are no big mining companies controlling opal production. Rather, the industry is made up of made up of small miners from all corners of the world. 

Before OPAL there was GOLD 

In the mid 1800’s Australia was gripped with  gold fever. Fortune hunters from all corners of the world poured in and fanned out over this vast land looking for the next big find. When they weren’t finding gold, they were finding deposits of other valuable and useful minerals such as silver, lead, zinc, tin, and OPAL. While most of these minerals were used in industry, OPAL is pure gemstone sought for its rarity, beauty, and value. 

The first recording by colonisers of  opal being found in Australia was in the mid-1840s when a German prospector Johan Menge found opal in Angaston, in the Barossa Valley, South Australia (O’Leary, 10). 

Commercial production of opal did not begin until the 1880s with the arrival of the entrepreneur, Tully Cornthwaite Wollaston; an individual O’Leary argues is the founder of the Australian opal industry (O’Leary, 12). 

According to O’Leary, or so the story goes, Wollaston, at the age of 25, backed by a syndicate of wealthy businessmen, travelled from Adelaide to Central Queensland, by train, then camel, to meet a miner. Through deserts, in the heat of summer, during the worst drought ever recorded, he was determined to meet an old opal miner called Joe Bridle who was rumoured to be “on colour”. After some persuasion Bridle agreed to sell Wollaston a parcel of high-quality opal, which Wollaston went on to sell overseas. 

Wollaston took the parcel of opal to Europe, but a lack of interest drove him to explore the American market (O’Leary). 

The American market embraced opal and this opened up trading opportunities that had never existed before.

3. Opal Miners

An opal miner must like living in the bush. 

The most successful miners are those who know the land. 

Bushman, whether on horseback or foot, spend a lot of time looking at the ground they are moving on. 

The first generation of opal miners – Opalers – were usually bushman such as, cowboys, shearers, station hands, fencers. These chaps would go opal mining when they had time off and “fossic”, leaving behind valuable landmarks for the next generation of miners. 

Abandoned old timers’ mines have historically been where some of the richest deposits of opal have been found in modern opal mining era. The modern era (from the 1960s) heralds the arrival of heavy machinery and open cut mining. 

To mine opal, you either know the country well or have someone introduce you to it. It is almost impossible to just turn up to the opal fields, peg a claim, and start digging. Someone must introduce you into the industry. 

Miners usually buddy up so there’s always someone looking for a partner. 

When my father Vince Evert began opal mining in the mid 1970’s he was mentored by an old timer called Mr. P. Mr. P. was a bushman. He had lived his whole life in the bush and knew opal well. He would invite my father out to his camp and pass on knowledge to him. They were great friends who loved the bush and chasing opal. 

In the old days, teams of two were necessary for, one would work the windless and the other would go down into the shaft, dig for the opal and fill the bucket with dirt which the miner on top (at ground level) would empty and sort the contents. The person on the ground is also responsible for overseeing safety and staying in touch with the miner down the shaft. The mining industry is full of hazards with reports of accidents happening all the time. 

In the modern era it’s a matter of economics. 

In a partnership/syndicate everyone brings something to the table. One partner may have local knowledge (and leases) and the other partner may have machinery and mechanical knowledge. Another partner may have funds to back the project. In an arrangement like this the partners usually agree on a percentage of the find.

Opal mining in the 1940s

4. Camp Life

Living in the Australian bush has never been an easy way of life. 

There is an element of the  frontier to bush life. Because opal is found over a vast area, miners usually establish a base/main camp. The main camp usually consists of a few formal dwellings. The main “house” is usually a caravan, a bus, a shipping container, or an old train carriage. 

A typical opal mining camp will have a main house, an outhouse, a water tank, a machinery shed, a generator, an opal cutting area and “dumps” of opal bearing rocks. 

A mountain of opal bearing rocks – a “dump” 

If you happen to be driving by an opal camp you can’t just show up (unless you’re lost in the bush, of course). You must be invited. The meeting is arranged and supervised. 

Picking up the opal from the opal mine under the supervision of the miners. 

Opal mining camps are found on cattle stations. 

Australian mining laws argue that mining takes precedence over farming on Crown land. 

Crown land is land that the government leases, in this case, to cattle growers. 

When it comes to finding opal, the deposits are located on grazing land. 

With the right documentation a miner can set up a camp and mine without harassment on a grazing property under pastoral lease. 

Miners and grazers must work together. Sometimes it is not always possible, and graziers lobby the government, through the Mines Department, to review the laws and change them to keep in step with the modern time. 

The small mining industry is under current review. The Mines Department is looking to abolish “claims” and make the entry into mining, leases. Basically, claims offer short term tenure and lease term tenure. Small miners prefer claims over leases for their own reasons and graziers prefer leases over claims for their own reasons. 

I intend to explore this issue in my next blog so make sure you’re on the mailing list to read about it then.

5. Camp Communication

Communication in the past took the form of snail mail (letters and parcels), short-wave/two-way radio, satellite telephones and now the internet. 

Letters were the main form of communication in the bush, before the arrival of radio and the transport of mail has always been a priority in the bush. 

The  mail run is the lifeline of the Australian bush. A contractor from the nearest town will bring the mail, or orders from the local stores, out to the various cattle stations and opal camps, in a truck, on a weekly basis. 

The short-wave/two-way radio was installed into camp life when that technology came available and was used by residents of the outback well into the late twentieth century. 

Nowadays, opal mining camps have access to all forms of technology so now it’s as easy as mining the opal, cutting it at your camp, photographing it, listing it on your webstore, selling it and dispatching it in the post via the mail run. 

A short-wave radio set.

6. Opal Formation

Raw opal, or rough opal, is a unique natural gemstone found in a vast area of central Australia in several places located on the rim, and inside, of the Great Artesian Basin. The Great Artesian Basin is the largest underground water system in the world. 

To understand opal formation, one must go back to the beginning. 

Scientists argue that the foundations for the formation of opal began somewhere in the upper  Jurassic Period (199 – 145 million years ago) however the most important time in the formation of opal event occurred during the Cretaceous Period (145 – 66 million years ago) (Aracic, 82) 

A massive rise in sea levels, a relatively warm climate, and the formation of numerous shallow inland seas were characteristic features of the landscape during this time. 

In the Cretaceous Period, the planet was ice-free, forests stretched from one pole to the other and many new plants and animal species evolved. The oceans were full of, now extinct, marine life and the land was ruled by dinosaurs. Sadly, all this ended with the arrival of an asteroid 10 – 15 kms in diameter that landed on the coast of Mexico 66 million years ago causing the mass extinction of many plants and animals (including the dinosaurs). 

Aracic argues, glaciers carried rocks which eventually found a home on the bottom of the shallow inland sea covering one third of the Australian continent. The vast inland sea created large depressions, freshwater lagoons, and swamps in which the rocks came to rest eventually filling with SiO2+ H2O gel or OPAL. 

Popular theory argues that the surrounding environment was rich in Silica and that the Silica bonded with water the form a gel. This gel then flowed into cracks and crevices in the clay beds in South Australia and New South Wales, and huge boulders sitting on the ocean floor in Queensland, where it organised itself into a micro structure unique to OPAL. 

The opal formation event is dated through identifying fossils and opalised plant and animal life, found in the strata, relating to the relevant period. Aracic argues, there were two signification periods in opal formation. The first being the upper Jurassic to the Cretaceous Periods and the second being the from the late Cretaceous to the Quaternary periods. 

Is it possible that the older opal formed in the time between the upper Jurassic and Cretaceous Period present as gem grade opal, i.e., opal that is stable with complex colours and patterns – play of colour? And that the younger opal formed at the end of the Cretaceous Period and upper Quaternary period is more in the realm of specimen grade opal, i.e., opal that is less stable (cracks), has little play of colour often being limited to one or two colours and is in some cases abundant in its presentation. This opal is referred to as common opal or potch.

7. Precious opal and Common opal

Precious opal is opal that has complex colours and patterns. 

Precious opal is prized for its “play of colour”. 

Common opal is opal that is usually only one or two colours at a time and lacks the “play of colour” seen in precious opal. 

Let me try to explain how precious opal exhibits “play of colour” and why common opal does not. 

There is no definitive explanation for how opal gets its colour however there are two key theories. 

One relates to the internal structure of the opal and the other relates to the composition of these internal structures. 

The internal structure of opal. 

Under an electron microscope precious opal is made up of a closely stacked, uniformly arranged, spherical silica micelles in a three-dimensional grid. 

  • A micelle is an aggregate (a material or structure formed from a mass of fragments or particles loosely compacted together) of molecules in a colloidal solution.
  • A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance.

In precious opal, the colloid solution in which the spherical silica micelles sit in, is silica in solution. When light passes directly through the transparent spheres it reaches the silica in solution and is diffracted at angles producing colour. 

O’Leary argues that the spherical silica micelles are packed in a multi layered three-dimensional grid which means that when light passes through the many layers of uniformly arranged silica spheres the overlapping layers produces colours and pattern unique to that opal. In short, every opal has a unique structure, or fingerprint, which is why no two opals will ever look the same. 

One more thing… 

The colour emitted from the opal is dependent on the size of the spheres which determine the wavelength (Cody, 15). 

Blue colours present when the spheres are small and red colours present when the spheres are large. The intensity and brilliance of the colours depends on the size of the spheres and the way they have been packed in the grid. 

As well as structure (size of spheres and arrangement in grid) Aracic, argues one must consider what minerals are also contained in the silica solution in which the spheres sit. These factors contribute to making every opal unique. 

Common opal presents quite differently to precious opal when viewed under an electron microscope. 

Common opal, or potch, has the same chemical formula are precious opal but lacks the complex spherical grid structure of precious opal described above. When it comes to common opal the silica spheres are not packed in a uniform grid pattern but rather are of varying sizes and present in an abstract pattern. 

While common opal exhibits some colour, it does not produce the complex colours and patterns seen in precious opal.

8. Where is raw opal found?

Raw Australian Opal is found in locations on the rim, and inland, of the Great Artesian Basin. 

White opal and crystal opal is found in South Australia in the area near and around the townships of Coober Pedy, Andamooka and Mintabie. 

Black opal is found in New South Wales near and around the townships of Lighting Ridge and White Cliffs. 

Boulder, matrix, Yowah, Koroit, crystal and pipe opal are found near and around the townships of Winton, Quilpie, Yowah, Koroit, and Eromanga. 

One must remember these towns are simply reference points and that the opal fields are not actually located in these towns but in the bush near and around them. 

How is black and white opal different from boulder opal? 

The key defining feature of each type of opal is the host rock, and common opal, the opal is found in. In each area the host rock, and common opal, in which the vein of precious opal is found, is different. 

As a result, each type of opal has its own defining look based on the host rock and common opal the precious opal is found in. 

White and black opal are found in clay beds. Popular theory argues that the opal gel flowed into pockets and crevices in the clay beds, filling the voids with SiO2nH2 gel and forming deposits of opal referred to in the industry as “nobbies”. 

White opal and crystal opal is found in clay beds, in South Australia, and is characterized by the white common opal the precious opal is found in, hence the name. 

Black opal like white opal is found in clay beds and is characterized by the black common opal the precious opal is found in, hence the name. 

Boulder opal is found in rock. Veins of opal are found within large ironstone/sandstone rock boulders. The opal is naturally bonded to the rock making it impossible to separate the rock from the opal. A boulder opal that is naturally bonded to the rock is considered a solid opal. Boulder opal is unique to the Queensland opal fields. 

A map of the Australian Opal Fields (Cody, 66,67)

9. Opal mining in the current time

As mentioned before, the opal mining industry is a boutique industry made up of many  small miners having a go. In 2021 the Queensland Government placed a 12-month moratorium on issuing new claims while it reviews the mining laws. 

Opal mining is not the only industry to come under spotlight, all small mining is under review, including gold prospecting (a favourite past time for many Australians). 

Small mining has always been a part of Australian life, but it seems it has become a victim of its own success. With the spike in interest in mining the number of people seeking to patriciate in the activity has risen and with the rise in interest has come a conflict of interest between those holding pastoral leases and those holding mining claims and leases. 

Submissions have been made, consultations have occurred, and findings are expected to be announced late 2022. 

10. Author Bio and References

  Therese Evert hails from Winton and grew up in the opal industry. Her father, Vince Evert, mined opal in the 1970s, training many cutters in his workshop in Winton, and was an active member of the opal industry all his life. Therese trained as a cutter, under the tutorship of her father, from 1982 to 1985. She has worked in the opal industry all her working life. Opal is her passion. 

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Edited and published by:  Digital Marketing Hub Australia


Aracic, S & M. Rediscover Opals in Australia. Self-Published in Lightning Ridge, Australia. 1999

Cody, A. Australian Precious Opal. Self-Published in Melbourne. 1991

Idriess, I. Lightning Ridge. Angus and Robertson, Sydney. 1940 

O’Leary, B. A Field Guide to Australian Opals, second edition. GEMCRAFT Publications, Victoria. 1984