Large Libyan Desert Glass

About this specimen

This is the large piece in our Libyan Desert Glass stock: a single, sizable chunk of the pale yellow natural glass that only occurs in one strewn field in Egypt’s Great Sand Sea. Most material that reaches collectors is small, wind-polished fragments, so a piece of this size is where you can actually see the internal character of the glass: streaky flow banding (schlieren), trapped bubbles, and the frosted, sand-blasted skin that comes from millions of years of desert wind.

It is sold as a rough specimen, not cut or polished, and you receive the exact piece pictured.

Why a large piece matters

Libyan Desert Glass is one of the very few natural glasses clear enough to be faceted, and gem cutters report that faceted stones over 10 carats are uncommon and over 25 carats rare (Sky Jems). Big rough is what makes those stones possible, and it is also what museums and serious tektite and impactite collectors look for, because larger pieces preserve more of the original melt texture.

Libyan Desert Glass: the newer science

• Impact, not airburst: for years the leading idea was a giant aerial explosion, described as a roughly 100-megaton-class airburst. In 2019, Aaron Cavosie and Christian Koeberl reported in Geology that zircon grains in the glass preserve evidence of reidite, a mineral that forms only under shock pressure. Their point: airbursts can melt the ground, but only a meteorite striking it creates the shock waves that form high-pressure minerals (Curtin University).
• The strewn field: the glass is scattered over an elliptical area of roughly 4,000 square kilometres between the dunes of the Great Sand Sea (Sky Jems).
• Tutankhamun’s scarab: the yellow scarab at the center of a pectoral from Tutankhamun’s tomb was long described as chalcedony. Italian mineralogist Vincenzo de Michele identified it as Libyan Desert Glass in 1998 (Sky Jems).
• What’s inside: under magnification the glass can show sub-microscopic cristobalite and lechatelierite, pure silica glass that forms only at extreme temperatures (Sky Jems).

Questions about this piece