What Are Tektites? Origin Formation and Strewn Fields

Tektites are one of those things that sound complicated until someone explains them properly.

So what are tektites, really? They're not meteorites. They're not volcanic glass. They're not man made. They're natural impact glass, formed from Earth material during large meteorite strikes, and they're genuinely one of the more interesting things you can hold in your hand.

Here's what they actually are and where they come from.

What are tektites made from?

The first thing most people get wrong is thinking tektites are pieces of meteorite.

They're not.

A tektite forms from Earth material, not from the space object itself. When a large meteorite hits Earth, the energy is so extreme it melts and vaporises rock and sediment near the surface. Some of that melted Earth material gets thrown away from the impact zone, cools fast in the air and solidifies into natural glass before landing.

That's a tektite.

The impactor comes from space. The glass comes from Earth.

Real tektites also have specific physical traits that separate them from things like obsidian or slag. Very low water content. Low alkali content. And something called lechatelierite, which is pure silica glass that only forms under the kind of extreme heat you get from an impact event. That combination is part of why tektites are recognised as their own distinct category rather than just another dark natural glass.

A collection of tektite specimens from different regions, showing the natural range of forms created by meteorite impacts

How do tektites form?

The process itself is straightforward once you break it down.

A large meteorite hits Earth at extreme speed. The energy melts material at and near the surface. Some of that melt gets ejected away from the impact site. It cools rapidly while airborne and solidifies into glass before falling back down.

What makes tektites different from other impact glasses is where that material comes from. Tektites are derived from the very surface of the target area, which is part of why they can end up scattered so far from the original crater.

The shapes vary a lot depending on how the melt moved through the air during cooling. Some are small splash forms: teardrops, spheres, dumbbells, discs.

Others are layered and blocky, a type known as Muong Nong tektites. Sizes range from tiny microtektites you'd need a magnifier to see, up to pieces 10 to 20 centimetres across, though most genuine tektites are around a centimetre and weigh only a few grams.

Where are tektites found?

Tektites aren't scattered randomly around the planet. They show up in specific zones called strewn fields, which are geographic areas where tektites from the same impact event landed.

There are four major recognised strewn fields on Earth:

The Australasian field. The Central European field. The Ivory Coast field. The North American field.

Moldavite comes from the Central European strewn field, which is why it's only found in certain parts of the Czech Republic, Germany and Austria. If you want to see genuine moldavite pieces, you can browse the moldavite collection here.

Microtektites from three of these four fields have also been found in deep sea cores, which gives you a sense of how far the material travelled from the original impact sites.

One thing worth knowing: not every strewn field has a confirmed source crater. Three of the four do. The Australasian field is the largest of them all and its source crater still hasn't been found. A lot of writing about tektites glosses over that, but it's worth knowing the science isn't completely settled on every point.

World map showing the four major tektite strewn fields including the Australasian, Central European, Ivory Coast and North American fields

Why do tektites look different from obsidian?

People mix up tektites and obsidian more than anything else, which makes sense at first glance because both are dark natural glass.

The difference is origin. Obsidian is volcanic. Tektite is impact glass. Early researchers actually made the same mistake before the chemical and physical evidence became clearer.

The appearance varies depending on where a tektite is from. Most are black or dark brown. Some are greenish or grey. Moldavite is the most well known green example. You can also find dark Indochinite tektites here if you want to see the contrast for yourself. On the surface you can often see natural sculpting, pitting, internal bubbles and evidence of the high temperatures involved in forming them.

That's what gives real tektites their look. It's not just colour. It's the whole combination of texture, shape and what happened to them during and after formation.

Why do tektites matter?

Beyond collecting, tektites are actual geological evidence of ancient impact events.

Scientists study them to understand how impacts melt material, what the source rocks were like, how heat and pressure affected them and how far ejecta can travel. Because they're tied to specific strewn fields and age ranges, they help piece together parts of Earth's impact history that would otherwise be hard to trace.

They also matter for keeping things accurate. Not every unusual glassy object found in nature is a tektite. Tektites belong to a specific class with clear formation conditions, known strewn fields and identifiable physical traits. Once you understand that, the whole category becomes a lot easier to talk about with confidence.

They're records of extreme planetary events, in a form you can actually hold. That's what makes them worth understanding properly.

If you've got questions about tektites or want to see some of the rarer individual pieces, take a look at our collector stones here.

Frequently asked questions

What are tektites in simple terms?

Tektites are natural glass that formed when a large meteorite slammed into Earth. The impact melted rock and soil at the surface, flung it into the air, and it cooled into glass before landing. So a tektite is melted Earth, not a piece of the meteorite itself.

Are tektites the same as meteorites?

No. A meteorite is the space object that hit Earth. A tektite is made from Earth's own surface material that melted during that impact. The impactor comes from space, the tektite glass comes from the ground.

Is moldavite a tektite?

Yes. Moldavite is the green tektite from the Central European strewn field, found in parts of the Czech Republic, Germany and Austria. It's the most well known and sought after tektite because of its colour and clarity.

How can you tell a real tektite from obsidian?

The clearest difference is origin: obsidian is volcanic glass, tektite is impact glass. Real tektites have very low water content, low alkali content and contain lechatelierite, a pure silica glass that only forms under impact level heat. Their surface sculpting, pitting and internal bubbles also help set them apart.

Where can you buy genuine tektites?

You can see everything currently available, including Indochinites, Philippinites, moldavite and more, in the full shop here.