LIBYAN DESERT GLASS
-Libyan Desert Glass is named after the Libyan Desert, although its locality is actually in the Western Desert in Egypt
-Silica Glass area is located between sand dunes of the southwestern corner of the Great Sand Sea in the Western Egypt, near the border to Libya. Therefore the name ,,Libyan” Desert Glass is not entirely correct but refers to the traditional name of the desert.
-Libyan Desert Glass is concentrated not in one but in two areas.
-Only a few small fragments were found below the surface and none deeper than about 1 metre
-The Aterian People ( 30 000-18 000 years ago) were probably the first to recognize Silica Glass and make use of its special properties.
-Although LDG has been dated as 28.5 million years old, there is no evidence that man used it before Aterian times even though much older Nubian Sandstone handaxes have been found.
-May have been discovered as early as 1846
-The occurrence of SC was documented for the first time by Patrick A. Clayton in 1932
-Not until 1971 when a joint University of Texas-University of Libya team explored the western extremity of the area, they discovered an Egyptian plane, intact, with the remains of 9 passengers scattered about, lying where they died of thirst more than 3 years earlier.
- In 1998 it was discovered that a green scarab found amongst Tutankhamun’s tomb goods was carved from SC, not chalcedony, a form of quartz, as originally thought. It is fascinating to wonder, how this piece came out of the deep desert to end up in Tutankhamun‘s possession.
-The surface can vary from smooth pieces polished by the sand to rough uneven examples, each glass is different and colors vary from milk grey-white to light green and yellow,
-Color is mainly greenish yellow, varying from whitish to dark green or blackish,
-Some pieces have black blobs and lines running through them. These dark samples are rich in iridium, which is typical of extraterrestrial bodies such as meteorites or comets.
-The glass does exhibit small internal bubbles that include other elements. One of those elements is iridium, the presence of which indicates an extra-terrestrial origin. However, the glass reveals no evidence of other minerals found in the region, such as halite and alumina
-It is probably the purest natural glass in the world
-SG is one of the most rare minerals on earth- even more rare that diamonds
-It is called ,,glass” because it s natural glass made of fused silica.
- SG seems to be too pure to be derived from a messy cosmic collision.
-LDG is in its chemical and physical characteristics absolutely single and with no other natural glass comparable
-It does not fit any known category of natural glass. It has not formed from quick-cooling lava and does not have the earmarks of a tektite produced by high-velocity asteroid impact with Earth.
-The purity gives the glass some remarkable properties. It can be heated up to 1700 C before it begins to melt, over 500 C higher than other natural glasses. It can be dropped into water when red hot and it will not disintegrate.
-When SC is carried to the north the color changes because of the different intensity of the solar spectrum wave lengths
-LDG is harder than the steel in a knife blade
-It shows no impact tracks
-It has higher capacity of water inclusions than tektites
-Inclusions of organic substances have been found
Lowest refractive index: 1.4616
Lowest specific gravity: 2.21
Highest silica content: 98%
Highest lechatelierite particles: fused quartz
Highest water content: 0.064 %
Mineral classification: mineraloids
Moh’s hardness: 6.0
Density: 2.20 (g/cm 3)
Radioactivity: not radioactive
-Some theories have been proposed but none has been proven
-One theory is that there was a soft projectile impact: a meteorite may have detonated about 10 km or so above the Great Sand Sea, the searing blast of hot air melting the sand beneath.
-Another theory has a meteorite glancing off the desert surface, leaving a glassy crust and a shallow crater that was soon filled in. But there are 2 known areas of SG, were there two cosmic projectiles in tandem?
-If the explosion of a solid object, like a meteor, did not form the glass, then there remains one other method available- an enormous electrical discharge. The glass shards, then are the remains of large fulgurites.
-This field of glass must have been the result of airborne explosion. This event would have been 10 000 times powerful than an atomic explosion, with temperature reaching up to 1800 C
-Maybe SG formed as a result of unimaginably powerful cosmic event.
-The method by which it was created is open to question
-What has puzzled scientists is, how it came to be in this remote and inhospitable area
-How it was formed in the first place is a mystery. Why did it form here and nowhere else?
The enigma of this glass is:
1. The amount. It is the largest known deposit of a natural silica ( 98 %) on earth
2. Its distribution- the distribution is approximately elliptical
3. No LDG has been found at the nearest meteorite crater, located in Libya
4. SG cannot have been fused from the local exposed sandstone
5. Age of glass and dunes, the dune sand and dunes have been formed in a time estimated to be less than 1 000 000 years, yet the fusion track dates of the glass have a mean of 28 millions years
-Whatever happened in Egypt must have been much more powerful than an atomic bomb
-What strange is that another area where similar type of glass may be found is atomic test sites
-When the first atomic bomb exploded in New Mexico, the desert sand turned to fused green glass
-Maybe it is result of atomic war in the ancient past
Silica Glass still remains a mystery!