Unveiling the Fiery Origins of Australian Sapphires: Volcanic Connections in the Land Down Under?
There’s more to every single sapphire stone than just a deep blue colour and captivating sparkle.
Much more.
A newly released German study on how sapphires are formed in volcanic environments got us to reflect on the fascinating volcanic origin of Australian sapphires.
Each gem goes through a journey taking millions of years, and has truly fiery origins. Find out more about the incredible formation of Australian sapphires.
The geology of Australian sapphires
Australia is one of the world’s renowned sapphire sources. Producing beautiful stones alongside countries like Sri Lanka and Myanmar, it’s in great company.
Australia has a particularly key role in the production of blue sapphires, the most sought-after shade of these gems. Major deposits are found at Anakie, central Queensland and the New England district of New South Wales.
In 1902, a geologist working with the Queensland Mines Department reported that sapphires found in surrounding alluvials (rich soils) had likely been weathered out of nearby basalts. These basalts are a type of volcanic rock, containing a cocktail of minerals.
Discoveries since that date appear to back up the same claim. Almost all sapphires found have been in close proximity to the basalts of Cenozoic volcanoes, which first erupted during the Cenozoic Era, around 66 million years ago.
However, only the deposits in Queensland and New South Wales have been rich enough to allow for mining on a commercial scale across the country.
In fact, those two sources have produced more commercial-grade blue sapphires than any other in the world.
Today, Australia is famous for its parti sapphires, a stunning combination of green, blue and yellow. These stones have a unique composition and are therefore very valuable. Although Australia is the most well-known supplier of parti sapphires, they are also found in Madagascar and Tanzania and, in smaller quantities, in other parts of the world.
There are ongoing debates around the source rock for Australian sapphires. While alkali basalt is largely thought to be the source rock, there is conflicting evidence to say it’s actually the pyroclastic rocks associated with the basalts. The second theory states that sapphires crystallised in an unknown rock in the lower crustal/upper mantle parts of the earth, and eventually rose to the surface during a volcanism period.
While the jury on exact geology is still out, we do know that Australian sapphires make up more than 70% of the global blue sapphire supply.
New insights from recent research
The sapphire story goes back millions of years but new research continues to emerge today, refining our understanding of the formation of Australian sapphires and other gemstones around the world.
Just this year, geoscientists uncovered new findings about how sapphire grains found in the Eifel, in Western Germany, are formed in relation to volcanism.
Before the study, it was thought that sapphires form deep in the earth’s mantle. However, there could be a question mark over that, with sapphires being found in volcanic fields, where magma and rocks from the earth’s crust collide.
The Eifel region has always been a rich source of sapphires, but being low in silicon dioxide, there was never any real explanation of why so many sapphires originated here. Until now.
Professor Dr Axel Schmitt at Curtin University, Perth, explains:
"One explanation is that sapphire in the Earth's crust originates from previously clayey sediments at very high temperatures and pressure and the ascending magmas simply form the elevator to the surface for the crystals."
These findings could provide more clarity around the formation of Australian sapphires, though further study would be needed before we can be sure.
A comparison of Australian sapphires vs. German sapphires
Australian Sapphires
German Sapphires
Formation environment
Their origin is not fully understood, but they are associated with surface or near-surface volcanic activity.
According to the new study, they form higher in the crust (around 5km below the surface) where magma and crustal rocks mix.
Formation process
Typically associated with basaltic volcanism but there might be other possibilities. New research might shine a light on the need to re-evaluate this.
Form through the interaction of rising magma with crustal rocks.
Age
Date back to the Cenozoic Era, which began around 66 million years ago.
Formations began during the Cretaceous period (145 million to 65 million years ago), and some were created by recent eruptions (13,000 years ago).
Colour source
Blue Australian sapphires primarily get their colour from iron and titanium.
Blue German sapphires also primarily get their colour from iron and titanium, but the exact compositions might differ from Australian sapphires.
Size and quality
Australia is known to produce large, high-quality gems, often with various shades of blue.
The recent study doesn’t examine the size or quality of the sapphires.
Geological context
Often found in alluvial deposits, after being transported from their original volcanic sources.
Found in volcanic fields, according to the 2024 study.
The journey from magma to gem
We know that sapphires can be formed in volcanic environments, but what does that journey look like?
Let’s take a high-level view of the process:
1. Intense heat and pressure within the earth cause rocks to melt into magma, while minerals like aluminium and oxygen combine. Sapphire crystals are formed.
2. Other minerals cause these crystals to take on their colour (in Australia, this is usually blue) and they slowly grow within the magma.
3. Volcanic eruptions push the magma and sapphire crystals closer to the surface, and eventually through cracks in the earth’s crust.
4. The magma cools and the crystals settle into layers of rock near the surface. Rain and rivers erode these rocks (this process can take millions of years!) and the sapphires are carried to riverbeds, where they’re often found.
Looking specifically at the formation of Australian sapphires, we can thank some unique conditions for the deposits in the country.
Most deposits are found when an igneous rock, such as basalt, is weathered and eroded. This leaves behind tough minerals, such as sapphires, that end up in certain parts of the landscape after being transported by rivers and streams. These are known as “placer deposits” and they make up most of the sapphires in Australia.
Diverse geological formations in the sapphire-rich regions contribute to the incredible blue colour the country is most accustomed to. Trace elements such as iron and titanium impart unique colours to the stones, and these elements are incorporated during the geological processes that take place during the formation of sapphires.
It’s a completely natural process, but the complexity of it all only adds to the allure of sapphires.
The unique beauty of Australian Sapphires
Australia is praised for producing some of the world’s most beautiful sapphires, from the Black Star of Queensland to the Tomahawk Tiger, found at Tomahawk Creek in Queensland.
Sapphires in Australia were first extracted by gold miners in NSW in 1851. From the early days, the Australian sapphire has been known for its exceptional quality and vibrant hues.
While blue is truly the star of the show here, our sapphire deposits produce a diverse range of colours, including green, yellow and parti-coloured gems. The country is known for producing high-quality sapphires with few inclusions, as well as unique stones with thin, subtle lines of colours.
The environments in Queensland and New South Wales are ideal for creating sapphires with exceptional clarity and durability.
Appreciating the geological heritage
One of our favourite things about sapphires is their beauty isn’t just surface level.
The formation of Australian sapphires takes place over millions of years and begins deep within the earth. Not only that, but Australian sapphires are literally shaped by our landscape, which makes them unique - in their size, colour and quality - to our beautiful country.
This achievement isn’t lost on us here at Sapphire Dreams. That’s why we started the brand in the first place. We set out to pay homage to the natural beauty of Australian sapphires, bringing these impeccable gems into contemporary jewellery designs.
Because something this rare deserves to be celebrated.
Natural gems in beautiful jewellery
If you own an Australian sapphire, or buy one as a gift, now you know that gem started its journey from fiery origins. The geological story of sapphires often gives our customers a new-found appreciation for them, and brand-new research gives us an opportunity to dig even deeper.
Every piece in our collection carries a story of volcanic fire and geological wonder. You could be a part of one of those stories by owning your very own sapphire.