Libyan desert glass or Great Sand Sea glass is an impactite, made mostly of

lechatelierite Lechatelierite is silica glass, amorphous SiO2, non-crystalline mineraloid. It is named for Henry Louis Le Chatelier. Structure Lechatelierite is a mineraloid as it does not have a crystal structure. Although not a true mineral, it is often clas ...

, found in areas in the eastern

Sahara The Sahara (, ) is a desert spanning across North Africa. With an area of , it is the largest hot desert in the world and the list of deserts by area, third-largest desert overall, smaller only than the deserts of Antarctica and the northern Ar ...

, in the deserts of eastern Libya and western Egypt. Fragments of desert glass can be found over areas of tens of square

kilometer The kilometre ( SI symbol: km; or ), spelt kilometer in American and Philippine English, is a unit of length in the International System of Units (SI), equal to one thousand metres (kilo- being the SI prefix for ). It is the preferred mea ...

s. Like

obsidian Obsidian ( ) is a naturally occurring volcanic glass formed when lava extrusive rock, extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock. Produced from felsic lava, obsidian is rich in the lighter element ...

, it was knapped and used to make

tools A tool is an object that can extend an individual's ability to modify features of the surrounding environment or help them accomplish a particular task. Although many animals use simple tools, only human beings, whose use of stone tools dates ...

during the

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

Geologic origin

The origin of desert glass is uncertain.

Meteor A meteor, known colloquially as a shooting star, is a glowing streak of a small body (usually meteoroid) going through Earth's atmosphere, after being heated to incandescence by collisions with air molecules in the upper atmosphere, creating a ...

itic origins have long been considered possible, and recent research links the

glass Glass is an amorphous (non-crystalline solid, non-crystalline) solid. Because it is often transparency and translucency, transparent and chemically inert, glass has found widespread practical, technological, and decorative use in window pane ...

to impact features, such as

zircon Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of th ...

breakdown, vaporized

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

and meteoritic metals, and to an

impact crater An impact crater is a depression (geology), depression in the surface of a solid astronomical body formed by the hypervelocity impact event, impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal c ...

. Some geologists associate the glass with radiative melting from meteoric large aerial bursts, making it analogous to trinitite created from

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural ...

exposed to the

thermal radiation Thermal radiation is electromagnetic radiation emitted by the thermal motion of particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation. The emission of energy arises from a combination of electro ...

of a

nuclear explosion A nuclear explosion is an explosion that occurs as a result of the rapid release of energy from a high-speed nuclear reaction. The driving reaction may be nuclear fission or nuclear fusion or a multi-stage cascading combination of the two, th ...

. Libyan Desert glass has been dated as having formed about 29 million years ago. Analysis of samples with the electron backscatter diffraction (EBSD) technique revealed

crystal structures that form only when reidite melts at very high temperatures and is then converted to zircon. Reidite has been found only at meteorite impact sites, where it was formed at the very high pressures of impact. Airbursts never yield this type of mineral transformation.

References

Literature

* V. de Michele (ed.): ''Proceedings of the Silica '96 Meeting on Libyan Desert Glass and related desert events'', Bologna, 199
Contents
* P.A. Clayton / L.J. Spencer: ''Silica Glass from the Libyan Desert'', Vortrag vom 09.11.193

External links

{{Commons category, Libyan desert glass
Google Scholar: "Desert Glass"Glass in Nature from The Corning Museum of Glass
Glass in nature Geology of Libya Western Desert (Egypt) Impact event minerals Jewellery components Rupelian

Geologic origin

See also

References

Literature

External links