Inside The Largest Zircon Mine in the World

The Story of the Jacinth–Ambrosia Zircon Fields

Buried beneath the red sands of South Australia’s Eucla Basin lies a multi-billion-dollar treasure — but it isn’t gold or diamonds. It’s zircon, one of the most durable and valuable minerals on Earth. The Jacinth–Ambrosia deposit, operated by Iluka Resources, produces about a quarter of the world’s zircon supply — the microscopic crystals that end up in ceramics, electronics, jet engines, and even nuclear reactors.

Each tonne of that fine, pale sand is worth thousands of dollars, and the mine itself sits on what is effectively a fossilised coastline, stranded hundreds of kilometres inland. These dunes, silent and wind-scoured today, were once Eocene beaches washed by a tropical sea. Over tens of millions of years, those ancient waves concentrated the heavy minerals we now dig from the desert.

It’s one of Australia’s most unexpected geological jackpots — a discovery that took cutting-edge modelling, a bit of bold imagination, and a new way of seeing the landscape. The Jacinth–Ambrosia story isn’t just about mining; it’s about how 40-million-year-old beaches became a modern mineral empire, how billion-year-old zircons journeyed across a continent, and how a patch of remote desert became one of the most profitable pieces of real estate on the planet.

An Inland Beach 

Long before the mine, before the trucks and spiral concentrators, this land was part of a dynamic coastal plain fringing the Eucla Basin, a vast sedimentary basin stretching across the border of South and Western Australia. Today it’s a sea of red sand and mallee scrub. But rewind the clock 40 million years, and it was a wide coastal system of beaches, dunes, and lagoons — a tropical shoreline alive with wind and surf.

During the Eocene epoch — roughly between 56 and 34 million years ago — southern Australia was much warmer and wetter. The continent was still breaking free from Antarctica, and global sea levels were fluctuating wildly. With each marine transgression and regression, the shoreline crept inland and retreated again, building up a sequence of sandy barriers and coastal ridges. These old beaches became the skeletons of what we now call the Ooldea and Barton sand ranges, and they’d play host to something special.

As rivers from the north eroded ancient mountain belts — notably the Musgrave Province, the Albany–Fraser Orogen, and even the distant Yilgarn Craton — they carried with them microscopic treasures: zircon, ilmenite, rutile, and monazite, all durable minerals that resist chemical weathering. Every time those rivers reached the coast, they dropped their loads of heavy minerals into the surf. Waves and tides then went to work, washing and sorting those grains by density.

*Image depicts the Musgrave Province (Northern Yellow Section), The Yilgarn Craton (Red) and the Albany-Fraser Orogen (Western Yellow Section)

The lighter quartz grains got swept away. The heavier ones — the zircons, the ilmenites, the rutiles — settled into the swash zones of beaches, concentrating along the shoreline in bands just a few metres thick. Over time, storms, sea-level changes, and wind re-worked those deposits into new dunes. Layer upon layer, they stacked up, each one a faint geological echo of the ancient coast.

Eventually, the seas retreated for good, and the climate turned arid. The wind took over as the master sculptor, blowing quartz and heavy minerals inland, and shaping the dunes into long ridges. What remained buried beneath the surface was an extraordinary natural filter — a placer deposit rich in valuable heavy minerals.

Discovery in the Desert

Fast forward to the late 20th century. Geologists already knew about heavy mineral sands along Australia’s modern coastline — places like Stradbroke Island and the Murray Basin were famous for their ilmenite and rutile. But here, deep inland within the Yellabinna wilderness, no one had really looked.

That changed when scientists started to question the origin of the Ooldea and Barton dune systems. In the 1990s, geologists proposed something radical: these were not just random inland dunes — they were the fossilised remains of ancient beaches. Their studies suggested that coastal sediments had been stranded far inland by long-term uplift and sea-level fall. If that were true, the same processes that made rich beach placer deposits elsewhere might have also operated here, buried under the outback sand.

Iluka Resources, already one of the world’s major mineral-sands producers, took notice. The company’s exploration team began drilling in 2004, guided by those new geoscientific models and digital palaeogeographic reconstructions. What they found astonished them. Within three weeks of drilling, they hit the first of two incredibly high-grade zircon deposits — Jacinth and Ambrosia — sitting just a few kilometres apart on the western flank of the old Ooldea barrier.

Soon after came Tripitaka, and later Gullivers, Typhoon, and Dromedary. The Eucla Basin, long considered barren, had suddenly become a world-class heavy mineral province.

By late 2009, just five years after the first drillholes, the Jacinth–Ambrosia mine was in full production. That’s an unbelievably quick turnaround for a modern mining project. And in February 2010, South Australia’s Premier officially opened the site, marking the birth of what would become one of the state’s most profitable mining ventures.

The Anatomy of the Deposit

To really appreciate Jacinth–Ambrosia, you have to understand its geological architecture. These are not hard-rock mines — there’s no ore veins or granite to blast through. Instead, the mineralisation lies within unconsolidated sand, mostly above the water table, with just a few metres of overburden.

Picture a long, slightly curved dune ridge running north–south for about three kilometres. Within that ridge lies a core of heavy mineral sands — the high-grade zone — between two and ten metres thick, containing up to 20% heavy minerals by weight. That’s astonishingly rich for this type of deposit. Above and below that layer are lower-grade sands, typically one to five percent.

The mineral mix itself is what makes this deposit unique.
At Jacinth, zircon makes up roughly 47–50% of the heavy mineral suite, ilmenite around 30%, and rutile about 5%. At Ambrosia, zircon content is even higher, near 50%, though the overall grade is a little lower. To put that in perspective, most coastal mineral-sand deposits in the world have zircon making up only 10% or less of the concentrate. Here, zircon dominates.

The ilmenite is also special. Much of it has been chemically altered into pseudorutile and leucoxene, rich in titanium (around 64%), which is a premium feedstock for titanium dioxide pigments. Tiny accessory minerals like tourmaline, monazite, spinel, staurolite, and chromite occur as trace components, along with rare grains of xenotime and hematite. Even though they’re minor, they provide valuable clues about where the sediment came from.

And that’s where things get really interesting.

The Journey of a Zircon Grain

Every zircon grain in those dunes is a time capsule. These tiny crystals — usually less than 0.2 millimetres across — can survive billions of years of weathering and transport without losing their internal isotopic record. Geologists love them because they act like DNA for the Earth’s crust.

A 2013 study used hafnium (Hf) isotopic analysis to trace the origins of these zircons. Their results painted a fascinating picture. The majority of the zircons were born between 1.3 and 1.1 billion years ago during intense magmatic activity in the Musgrave Province — a belt of Proterozoic granites and gneisses that once formed the heart of central Australia. Some were older, around 1.7 to 1.5 billion years, linking them to the Albany–Fraser Orogen, while a few rare grains dated to around 2.8 billion years, pointing all the way back to the Yilgarn Craton, one of the oldest continental fragments on Earth.

Curiously, almost none came from the nearby Gawler Craton, even though it sits just east of the Eucla Basin. Why? Because during the Eocene, that region was a low-lying plain drowned by shallow seas. It simply wasn’t shedding much sediment. Instead, rivers from the west and northwest carried zircons from the highlands of the Musgrave and Albany–Fraser terranes, washing them into coastal systems where longshore drift swept them eastward for hundreds of kilometres. The result: the Eucla Basin’s beach deposits, including Jacinth–Ambrosia, are essentially a zircon export from the western half of the continent.

Think about that. Those sparkling grains mined today may have started their journey a billion years ago in magma chambers deep within the Earth’s crust near the NT–SA–WA border — and have since travelled through rivers, oceans, and dunes to finally rest in the middle of the desert.

From Dune to Dollars

At full production, Jacinth–Ambrosia can yield about 300,000 tonnes of zircon per year — roughly one quarter of the world’s supply — along with 45,000 tonnes of rutile and 170,000 tonnes of ilmenite. It’s hard to overstate how important that is. Zircon is used everywhere: in ceramics, electronics, refractories, and even as the precursor for zirconium metal and nuclear fuel cladding. In fact, your bathroom tiles and smartphone may contain zircon grains that once sat in those South Australian dunes.

What’s It Worth?

But let’s talk numbers, because the scale is mind-boggling.

At an average grade of about 5% heavy minerals, the Jacinth and Ambrosia deposits together contain roughly 10 million tonnes of heavy mineral concentrate within more than 280 million tonnes of sand. Since about half of that heavy fraction is zircon, that means around 5 million tonnes of zircon in situ.

Zircon prices fluctuate, but in recent years they’ve averaged between $2,300 – $3,000 Australian dollars per tonne for premium opacifier grades. Even conservatively, that puts the gross in-ground zircon value in the multi-billion-dollar range — potentially upwards of 10 – 15 billion Australian Dollars, not counting the titanium minerals, which add another substantial sum.

Of course, not all of that is recoverable or economically viable, but it gives you an idea of why Jacinth–Ambrosia has been called a “once-in-a-generation” discovery. It also helped secure Australia’s position as the global leader in zircon production, far ahead of competitors in Africa or Asia.

The Broader Picture: The Eucla Basin Province

The Eucla Basin isn’t just about Jacinth–Ambrosia. It hosts a whole chain of deposits — stretching across South Australia and into Western Australia. Collectively, they form one of the largest known heavy-mineral provinces on Earth. Some of these deposits remain undeveloped, waiting for the right economics or infrastructure.

Together they hint at a story of continental-scale sediment transport — rivers draining half of Western Australia feeding a coastal system that extended 2,000 kilometres.

A Quiet Giant

It’s easy to drive past the region and never know that beneath your tyres lies a world-class deposit formed by ancient seas. Yet the impact of that deposit ripples far beyond South Australia.

In the end, the Jacinth–Ambrosia story is a perfect blend of geology and imagination — a reminder that even in the quietest parts of the outback, the Earth still keeps its richest secrets just beneath the surface.

Here's the video we made on this on the OzGeology YouTube Channel: