The mysterious origin of twisted glass in Chile

Glass found in the Atacama Desert may have been the result of an ancient comet's explosion.

Shards of silicon glass, some dark blue and some black, were found in a 75-kilometer corridor in the Atacama Desert, according to a statement from Brown University. The individual pieces of glass are "twisted and folded" and can be up to 50 centimeters long.

The researchers who first discovered these pieces of glass theorized that they came from fireballs exploding in the atmosphere. However, another group later concluded that the shards of glass were the result of intense grass fires. At that time, the area was not a desert, it had sandy soil, but also trees and grass.

To find out the cause, researchers from the US and Chile conducted chemical analysis of dozens of glass samples found in this desert. Inside the glass, the researchers found minerals known as zircons, some of which have broken down into baddeleyite, a rare zirconium oxide mineral. According to the statement, the transition from zircon to baddeleyite typically occurs at temperatures higher than 3,040 degrees Fahrenheit (1,670 degrees Celsius), much hotter than the temperature a fire can reach.

The researchers also discovered minerals in glass that had previously only been found in meteorites and other rocks of space origin. Some minerals, such as cubanite and troilite, are similar to those discovered in samples from a comet called Wild 2 collected by NASA's Stardust mission.

Furthermore, the odd, twisted shapes of the glass also point to the intense heat and winds that would be generated by a comet explosion. The researchers concluded that these glass fragments were likely the result of a cometary explosion similar to Wild 2.

The researchers estimate that the explosion occurred about 12,000 years ago. They are also carrying out further studies in the hope of determining the exact time of the explosion and the size of the comet.