Libyan Desert Glass is usually a beautiful straw yellow or champagne yellow. It is aTektite material found in the Western Desert of Egypt near the Libyan border (part of the Great Sand Sea). The occurrence of this silica-glass was first documented by Patrick A. Clayton in 1932.
The major component of Libyan Desert Glass is Lechatelierite, a naturally fused, X-ray amorphous, almost pure type of silica. Lechatelierite forms on the impact of meteorites as a result of sand melting. It also forms when lightning strikes sand or other very SiO2-rich sediments and rocks. Lechatelierite is a mineraloid as it is amorphous and does not have a crystalline structure. Although not a true mineral, it is often classified in the Quartz mineral group. Quartz is also made of silica, but it has a crystalline structure. Lechatelierite is named after Henry Louis Le Chatelier (1850-1936), French-Italian chemist.
Until recently, Libyan Desert Glass was somewhat controversial. It was suspected to be a Tektite similar to Moldavite but was not associated with any meteor creator or impact zone. Researchers at the Center for Remote Sensing at Boston University have recently discovered a very large impact crater in Egypt 31km in diameter which seems to coincide with the formation of Libyan Desert Glass. This crater has been named the Kebira Crater. The association of Libyan Desert Glass with this newly discovered crater is tentative and further research still needs to be done.
Libyan Desert Glass is similar to other Tektites such as Moldavite and Indochinites. Tektites may be Meteoric Silica Glass as a result of the impact of a meteor on Earth. Tektites are usually found in association with meteor impact craters or suspected ancient craters. Their origin is not fully understood. The leading theory, the “Meteorite Impact Theory”, is that when a meteorite hits the Earth, the heat and pressure of the impact are so great that it causes rock and sand to be fused into glass or Tektites. Tektites, like all natural glasses, contain gas bubbles and “swirl” like inclusions.
| Chemical Formula: | SiO2 (95% Silica + Al,Ca,Fe,K,Mg,Mn,Na,Ti) |
| Silicon Dioxide + various impurities |
| Crystallography: | Amorphous (natural glass) |
| Crystal Habit: | None |
| Twinning: | None |
| Cleavage: | Poor/indistinct, none |
| Fracture: | Conchoidal, Sub-conchoidal |
| Tenacity: | Brittle |
| Moh’s Hardness: | 6.5 – 7.0 |
| Density: | 2.20 – 2.65 (g/cm3) (estimated) |
| Luminescence: | Not Fluorescent |
| Radioactivity: | Not Radioactive |
| Color: | Yellow, pale yellow, almost colorless |
| Transparency: | Transparent to Translucent |
| Luster: | Vitreous |
