08 - 09
When you imagine the desert, you only see an endless expanse of sand and rock, the former often on the move, the latter stationary, both battered by the wind into intriguing features.
In one corner of the Sahara, near the extremely inhospitable Great Sand Sea, between the Kouffra Oasis and the Gilf Khabir Plateau in southwestern Egypt, close to the Libyan border, you can add to this archetypal image a field of serendipitously exposed gemstones, glaring brilliantly in the scorching desert sun. It is the only such field in the world, and those glittering objects are Libyan Desert glass.
The ‘corner’ above belies the vastness of this Libyan Desert glass field; it’s a region roughly measuring 130km by 53km, covering an area more than 6,500km2. All around, are fragments and chunks of Libyan Desert glass, ranging in size from small, barely noticeable pebbles, to the very large; the biggest piece yet discovered measured 28kgs.
Generally, they have a yellow hue, but can also be transparent; there are rarer shades of black or green, which according to some experts, point to an exotic origin story.
The Libyan Desert glass is primarily silica, like the sand upon which it is found, which has led scientists attempting to explain its origin to theorize that the desert sand must have been superheated by a cosmic event to form this very unique glass.
The prevailing theory is that, about 28.5 million years ago, a meteorite hit that particular spot, or a comet exploded close enough to the surface without impacting it, raising the temperature to more than 2,000oC, resulting in the formation of this unique silica glass.
Besides forming Libyan Desert glass, the sudden upsurge in temperature resulted in black, diamond bearing rocks, according to a 2013 study.
This theory of a cosmic event stands challenged by a few facts, beginning with the discrepancies in ages. The silica glass is estimated to be more than 28 million years old, but the sands in the Great Sand Sea are about a million years old, so it couldn’t have been created from this; additionally, as you may know, the scorching desert that is the Sahara only became so fairly recently, and as recently as 50,000 years ago, the area that is the Great Sand Sea had a climate quite similar to the Mediterranean. So, not a lot of sand to go by.
But it gets some slight support from the fact that the layer beneath the dunes, the Nubian Sandstone, is about a 100 million years old.
But there’s one gaping hole in the meteorite theory; no definite impact crater.
Whatever its origin, the Libyan Desert glass was treated as a gem worthy of a living god, as it is that outstanding scarab centerpiece on the Pharaoh Tutankhamen’s pectoral.