The whole thing about desert glass is the high temperature it takes to make it. When I say high, I mean crazy high! Like atomic explosion high, ya know? This article from Listverse will explain all the details for you much better than I could.
photo via Wikipedia
Tests on a scarab jewel that once belonged to King Tut proved that the glass it was made from was produced before the earliest Egyptian civilization. Curious for answers, scientists discovered an area in the Sahara Desert where mysterious blocks of glass litter the sand. The first atomic test in New Mexico in 1945 left a similar fingerprint.
The detonation left behind a thin sheet of glass, but the Egyptian glass eclipsed the test site in sheer size. Whatever event made the glass had to be hotter than an atomic explosion. The suspects include a meteor impact or a phenomenally hot air burst. Since there is no evidence of an impact crater, scientists tested the air burst theory with computer simulations. Results showed that if a Shoemaker-Levy type impact exploded into Earth’s atmosphere, the resulting fireball would hit the ground surface like a furnace, cooking sand into glass with temperatures up to 18,000 degrees Celsius (32,500°F).
Interestingly enough, this correlates with the zircon that was found in the Sahara glass. By measuring how degraded the zircon is, the heat the sample was exposed to can be calculated. The Egyptian glass gave a reading roughly the same as the simulation. Nothing terrestrial can create that kind of heat, which makes the air burst theory very plausible.
Whatever it was, it’s hit the planet before. In Southeast Asia, 800,000-year-old glass stretches over an area of almost 800 square kilometers (300 mi2). It’s suggestive of an event deadlier than the one that created the Egyptian glass field.
It's been hot enough around here this summer that I expect to find some of this glass out in my yard! Wait...I can't. I have no sand in my yard! Wonder what those temps would do to gumbo?
Coffee out on the patio this morning, OK?