The Unique Meteorite Crater in Australia

The Impact Crater Unlike Any Other

If you drive out into the dry, stony country northwest of Mount Magnet in Western Australia, you’ll eventually reach a lonely patch of land called Dalgaranga Station. The terrain here is quiet and ancient—flat granite plains broken by low rises and spinifex. At first glance, there’s not much to see. But hidden out here, surrounded by scrub, is one of the strangest little craters on Earth.

It’s only about 24 metres wide and a few metres deep—so small you could walk across it in under a minute. Yet this tiny dent in the Australian outback tells a story unlike any other. It’s the only confirmed crater in the world made by a mesosiderite meteorite—a rare type of stony-iron meteorite that’s half metal, half rock. But what makes Dalgaranga Crater truly unique — not just in Australia, but globally — is that it’s the only confirmed impact crater on Earth formed by a mesosiderite meteorite.

So, how did such a rare and peculiar thing end up here in the Yilgarn granite country of Western Australia? And why did it take decades for scientists to properly understand what they were looking at?

*Image shows the Dalgaranga Meteorite Crater in Western Australia 

The Discovery That Almost Didn’t Happen

The story begins in 1921, when an Aboriginal stockman named Billy Seward spotted a strange circular depression while mustering cattle on Dalgaranga Station. He told his boss, the station manager Gerard Wellard, who went out to have a look. What he found puzzled him—a neat little crater with a raised rim and fragments of metallic material scattered around it.

At the time, meteorite craters weren’t well understood. Even famous ones like Barringer Crater in Arizona were still controversial—many scientists still thought such features were volcanic. So when Wellard sent a few small fragments to Perth for examination, they didn’t cause much of a stir. The samples were misplaced, misidentified, or simply ignored.

And that’s how one of the most unique impact sites in the world fell into obscurity for nearly two decades.

It wasn’t until 1938 that the crater was finally reported in the scientific literature by E. S. Simpson of the Western Australian Museum. But even then, the details were sketchy, and nobody realized the true significance of the site. It took another 40 years before a proper geological survey was published. The delay wasn’t due to lack of interest—it was a comedy of errors: wrong coordinates, lost samples, and a series of misunderstandings that sent researchers chasing their tails.

By the time scientists returned to Dalgaranga in the 1950s, the crater was weathered but still remarkably well preserved—protected by its remote location and the arid climate of inland Western Australia.

A Small Crater with a Big Mystery

When researchers finally began to study the site properly, they realized that Dalgaranga was different from any other small crater known at the time.

For starters, it’s tiny—only about 70 feet (21 metres) in diameter and roughly 3 metres deep. That makes it one of the smallest recognized meteorite craters in Australia, and one of the smallest isolated craters in the world.

Normally, such a small crater would be caused by a fairly modest meteorite—something maybe the size of a big armchair. But when scientists collected and studied the fragments around Dalgaranga, they found something completely unexpected.

The meteorite wasn’t made of the usual iron or stony material. Instead, it was a mesosiderite—a rare kind of meteorite that’s a chaotic mix of both. Think of it as a cosmic fruitcake: chunks of silicate rock (like pyroxene and plagioclase) embedded in a metallic iron-nickel matrix. These meteorites are so unusual that they make up less than 1% of all meteorites ever found.

What Exactly Is a Mesosiderite?

To understand why Dalgaranga is so special, we need to zoom out—way out, to the early solar system.

Mesosiderites are stony-iron meteorites, but not like the better-known pallasites (those gorgeous ones with green crystals suspended in metal). Instead, mesosiderites are brecciated—that is, they’re mixtures of rock fragments cemented together by metal.

They likely formed when two differentiated asteroids—meaning bodies that had already separated into metallic cores and rocky crusts—collided catastrophically. The impact shattered and mixed the materials, welding together metal from one asteroid and silicate rock from another. So when a mesosiderite hits Earth, it’s like receiving a sample of two worlds fused by violence billions of years ago.

And Dalgaranga is the only place on Earth where we can see what happens when one of these strange hybrid meteorites slams into the ground.

The Meteorite Fragments and What They Reveal

For years, the biggest question was simple: what exactly fell here?

Early collectors like H. H. Nininger and G. Huss described the meteorite as mostly stony, perhaps 90% rock with just a little metal. But in the 1960s, geologist G. J. H. McCall from the University of Western Australia revisited the site and obtained two tiny but crucial fragments from within the crater.

One of them was mostly rusted iron oxide—pretty unremarkable. But the other was something else entirely: a stony fragment containing a delicate mix of nickel-iron and silicate minerals. McCall had thin sections made—a microscopic slice so thin that light passes through it—and what he saw confirmed Dalgaranga’s uniqueness.

Under the microscope, the sample revealed a chaotic mosaic of minerals:

Olivine crystals (a magnesium-iron silicate common in meteorites),

Hypersthene, a type of pyroxene mineral,

Bytownite/labradorite, a calcium-rich feldspar, and

Veins of metallic nickel-iron and troilite (iron sulphide).

These minerals weren’t arranged in the neat, rounded chondrules typical of ordinary meteorites. Instead, they were fractured and interlocked, showing signs of brecciation and partial melting. The texture indicated a history of intense shock, crystallization, and later intrusion by metal.

In short, McCall concluded, Dalgaranga’s meteorite wasn’t a simple stony rock—it was a mesosiderite, a stony-iron meteorite that had been through a long, violent evolution before it ever reached Earth.

A Meteorite’s Life Story

So what did McCall’s study tell us about the meteorite’s journey before impact?

The evidence suggested that the parent body of the Dalgaranga meteorite had once been differentiated—it had a metallic core and rocky outer layers, much like Earth. At some point, another body slammed into it, mixing the molten metal with crustal rock and creating the patchwork texture we see in mesosiderites.

Over millions of years, fragments of this mixed material broke off and wandered the solar system as small asteroids. One of these fragments—maybe just a ton or two in mass—eventually crossed Earth’s path.

When it entered our atmosphere, it probably broke apart slightly, slowed down, and struck the ground at relatively low speed. McCall estimated it had lost most of its “cosmic velocity” before impact—meaning it wasn’t coming in at tens of kilometres per second like most meteorites, but perhaps just fast enough to blast out a small crater in the hard granite bedrock.

That explains why Dalgaranga looks the way it does: shallow, slightly asymmetric, with no evidence of fused rock or melted glass. The meteorite didn’t vaporize or explode; it simply smashed into the ground, fragmented, and scattered its metal-silicate mixture around the rim.

The Geology Beneath the Crater

The crater sits in Archaean granite—some of the oldest rock on Earth, more than 2.5 billion years old. This granite is part of the ancient Yilgarn Craton, the stable continental core of Western Australia.

When the meteorite hit, it punched into this crystalline rock, excavating a simple bowl-shaped depression. The ejecta—the material thrown out by the impact—was asymmetric, suggesting the meteorite came in from the south or southeast at a low angle.

Unlike larger craters such as Wolfe Creek or Liverpool, Dalgaranga doesn’t have a steep, overturned rim or central uplift. It’s what geologists call a simple crater—a clean bowl with some brecciated rock and scattered ejecta around it.

Over time, rain and erosion filled the crater with coarse sand and feldspar fragments eroded from the surrounding granite. Today, it’s partly infilled, with low bushes and ironstone rubble masking its outline—but the rim still stands out if you know where to look.

How Old Is It?

That’s still an open question.

Because Dalgaranga is small, you’d expect it to erode away fairly quickly—at least on geological timescales. Yet it’s still clearly visible, which suggests it’s relatively young.

Some researchers have proposed an age of just a few thousand years—possibly younger than 10,000. Others, based on cosmogenic isotope dating (using isotopes like beryllium-10 and aluminium-26), have suggested an upper limit of around 270,000 years.

Whatever the exact figure, it’s young enough that its form hasn’t been completely erased, but old enough that all the metal fragments have heavily oxidized to rust. The desert climate has acted like a time capsule, preserving this tiny geological scar in remarkable condition.

A Case Study in Scientific Persistence

For years, confusion surrounded almost every aspect of Dalgaranga: the location, the size, even the identity of the meteorite. Early researchers described it as mostly stony; later studies showed it was stony-iron. Estimates of the projectile’s mass varied wildly—from 20 tons down to just one or two. Even the crater’s coordinates were misrecorded for decades, causing scientists to visit the wrong site more than once.

Why Dalgaranga Matters

You might wonder why such a tiny crater, barely visible from the air, got so much attention from scientists. The answer lies in what it represents.

Every crater tells a story about the history of our planet and the solar system—but Dalgaranga tells one of the rarest. It’s physical proof of a mesosiderite impact, a collision involving a fragment of a once-mighty asteroid that had been shattered and reassembled in deep space.

Preserving a Cosmic Relic

Today, Dalgaranga is protected under Western Australian law, though it’s still on pastoral land. Visitors who make the long, dusty drive out there can still stand on its rim and imagine the moment of impact—when a glowing mass of metal and stone screamed through the atmosphere and punched into the granite plain.

Most of the meteorite fragments have long been collected by museums and researchers, but if you walk the area carefully, you might still spot a tiny fleck of oxidized iron among the quartz and gravel. Each fragment tells part of a 4.5-billion-year journey, from the formation of the solar system to the quiet plains of Western Australia.

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