Walking on Glass: The Mystery of Libyan Desert Glass

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A Guide to Libyan Desert Glass: What It Is and Where It’s From

Coming from the deserts of the Eastern Sahara, Libyan Desert Glass is a strange mineraloid not found anywhere else in the world. With a strange origin and a deep yellow color, it’s long been an ornament used by humans but limited to the immediate geographic area in many cases. With the world more connected than ever before, and an ever-increasing appetite for mineralogical oddities, it’s possible to get your hands on some easily these days.

But what is it? Where does it come from? How do I know if a piece is real? Well, read on and I’ll fill you in with our guide to Libyan Desert Glass.

What is Libyan Desert Glass?

Libyan Desert Glass

We’re not sure exactly what event caused the formation of Libyan Desert Glass, only that it occurred from a meteoric impact somewhere in the range of 29 million years ago.

Its presence along the modern Egyptian/Libyan border was important in the past, it was often cut as a gemstone and was even used occasionally as a tool. Neolithic flake tools made of the material, such as scrapers, have been found in several locations.

There are a lot of these artifacts available online, but things are a bit iffy on the legality of this. All Egyptian artifacts exported after 1970 are theoretically illegal, but portions of the strew field are also found in Libya. Libya doesn’t appear to have the same protections in place, which makes the whole thing a bit murky since it would be an easy affair to move the items from Egypt through Libya.

The actual chemical composition is fairly simple. The majority of the material is made up of the mineraloid lechatelierite. This is a form of amorphous silica, or glass, associated with high-temperature events like lightning, nuclear explosions, and meteorite impacts.

What’s unique about this glass is its high purity of silica. It appears to be the most “pure” glass of natural origin known.

Libyan Desert Glass is spread across a large area where it’s found, and it’s readily available online for those interested.

How Was It Formed?

Libyan Desert Glass is a strange glass that comes out of the Sahara desert, specifically on the Eastern end. It’s thought to be an impactite, meaning that it was formed by the strike of a meteor or other extraterrestrial body. The current theory is that an airburst of the body in question created intense heat over a large portion of the desert, forming this glass.

An impactite is actually from the sand underneath the blast of the meteor. An iron-bearing meteorite moving at over 25km/s carries a ton of energy. Like, unimaginable amounts. On impact, a substantial portion of that energy would instantly convert into thermal energy.

How hot are we talking? Well, over 1,600°C (or ~3,000°F). This insane heat would have converted the relatively pure glass of the Sahara into a liquid instantly before it cooled off forming what we now know as Libyan Desert Glass.

While the most valued pieces of this glass are simply a brilliant yellow and highly translucent, there are other sorts found. The impact also appears to have formed cristobalite, which appears in the glass itself as small white spherules or dark spots.

Other inclusions found have included rutile and various forms of zircon. The most important is reidite, which is known only to form during impacts. Reidite actually breaks down during high temperatures, so identification was undertaken by identifying the way the zirconia (another zircon mineral) crystal grains lay.

libyan desert glass specimen
Libyan Desert Glass (credit: James St. John/Flickr)

There’s a lot of similarity to the tektite moldavite which is found in Southern Bohemia, at least in origin. The Libyan Desert Glass’ formation appears to be older and its formation was aided by the relatively pure silica concentration of the Sahara desert’s sands.

Some Libyan Desert Glass has the appearance of thumbprints or other markings. On proper meteorites, these are called regmaglypts and you’ll occasionally see someone claim that they’re ripples from the material being thrown into the air. More likely, these are just etchings and normal erosion from millions of years of exposure to desert sands.

It’s a fascinating story overall, and one that’s a bit unique when you take into account ancient use of the material as well. So it’s little wonder that many people want to own a piece of their own, but can you be sure of the authenticity?

Regmaglypts can be seen in this specimen, although subtle.

How To Tell if Libyan Desert Glass is Real or Fake?

In an unfortunate coincidence, Libyan Desert Glass is similar to the stuff humans make. With the recent popularity of all things tektite, there are certainly fakes out there. Libyan Desert Glass is more common than some of the rarer tektites so you’re less likely to encounter fakes.

This is in contrast to something like moldavite, where I’m pretty sure the fake market literally outweighs the real amount of the tektite actually formed in the first place.

Coloration

Coloration will be your first clue if you’re buying online. The glass itself is always a yellowish color, but rarely with high saturation. A light yellow shade is often a good clue as to the veracity of the glass itself, but higher saturation specimens are often more sought after.

Inclusions

Outside of having a specialist take a look, I recommend grabbing a loupe and getting up close and personal with your piece.

There should be embedded particles in the glass itself, even if you can’t detect them with the naked eye. If it’s devoid of particles that can be seen with a 10x loupe and it wasn’t verified in the first place, I wouldn’t trust it.

Presence of Cristobalite

Cristobalite is often seen as small white or dark spheres in the glass itself, whether on a microscopic or macroscopic scale. It’s a good indication that you have the right stuff, although it’s certainly possible someone has come up with a way to form it synthetically.

In the end, you’ll end up having to find a specialist to take a look if you want to be 100% sure.

Overall Quality

The majority of fakes will be very low quality, essentially looking like banana-colored beach glass. This helps cover the interior and gives it a “natural” appearance that can fool some newbies. The color should instead resemble a chardonnay at the darkest, and the exterior is unlikely to be uniformly abraded.

Inclusions are probably the best clue, but everything can be faked with enough work. I don’t think that Libyan Desert Glass is worth enough at this point for truly synthesized fakes to start showing up but anything can happen.

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