A soft impact meteorite is believed to have occurred in 1908 at Tunguska in Siberia. In the case of the Siberian Impact site there is no fused glass.
According to an expert on impact physics, Mark Boslough [*2] of the Sandia National Laboratories in the US, it was estimated that an object of about 390 feet in circumfrence travelling at slightly over 12 miles per second could conceivably produce enough heat to melt sand and create glass without leaving a crater as it disintegrated in the atmosphere. Science Frontiers
Besides Darwin Crater in Tasmania, on the Austrailian mainland there is an impact crater at Henbury, central Australia. Impact glass is found there also, but it differs from the Libyan Glass in that it is denser and not heterogeneous.
The Libyan Desert Glass differs in structure and composition from any other naturally occurring glass formations found anywhere in the known World. It does not however differ significantly however from glass found at nuclear test sites.
The glass formed by a nuclear chain reaction is named Trinitite after the trinmity site where it was discovered after the first atomic explosion in the Modern Era - The Manhattan Project. [*1]
"When the first atomic bomb exploded in New Mexico, the desert sand turned to fused green glass. This fact, according to the magazine Free World, has given certain archaeologists a turn.They have been digging in the ancient Euphrates Valley and have uncovered a layer of agrarian culture 8,000 years old, and a layer of herdsman culture much older, and a still older caveman culture. Recently, they reached another layer of fused green glass."New York Herald Tribune on February 16, 1947.
It is not inconceivable that the nuclear chain reactions that may have created the Libyan Dessert Glass were initiated by a natural force currently unbeknownst to man. The discovery of an ancient natural nuclear reactor was discovered in 1972 in Gabon, Africa [See Oklo: Natural Nuclear Reactors], before this discovery scientists believed that only they could create the conditions essential for nuclear fission and atomic chain reactions suitable to blow up entire cities and create vast waste lands.
Related Article - Nuclear Warfare in Ancient India
Footnotes - References
1.Washington Post - "... impact sites around the world are not trinitite beads, but they have a similar shape. ...Debris hurled into the sky by those explosions might have dimmed the sun and triggered conditions similar to a nuclear winter. The timing coincides with the start of the Younger Dryas, a cold snap that lasted more than 1,000 years....Hermes and his team of international collaborators, among them a nuclear scientist and several geologists, believe that the cold conditions were triggered when a meteorite slammed into Earth, leading to the extinction of large mammals across North America and to lean times during which hunter-gatherers turned to organized agriculture.".
2. Graham Hancock - Magicians of the Gods. "It is quite noticeable reviewing the literature, that academics form themselves into gangs.... Mark Boslough a physcist on the technical staff of Sandia National Laboratories ... teamed up .."
3. "Bits of green glass, possibly fused in an ancient fireplace, is one thing; areas of fused green glass is something quite else again. And this site is not the only one. There are also the fused forts of the west coast of Scotland and elsewhere, in which one side only has been fused, as if hit from above by intense heat. Lightning occasionally fuses sand, but always in a root-like pattern.....So just what produced a whole stratum of green glass in various parts of Mesopotamia? " Ivan T. Sanderson