In connection with Vesuvius' eruption in 79 AD, the city of Herculaneum was buried together with several other cities, including Pompeii. A few years ago, researchers discovered a rare organic glass-like material in the skull of one of the victims. But how it was formed has long been a mystery – glass is rarely formed in nature.
Now, a research group has analyzed fragments of the glass mass using, among other things, X-rays and electron microscopy. Based on the investigations, their theory is that the brain was likely exposed to temperatures of at least 510 degrees Celsius before being rapidly cooled again.
This leads researchers to assume that the people in the city did not die from the lava that flowed into the city, as it reached a maximum of 465 degrees and then cooled slowly. Instead, they believe that the inhabitants were first hit by an extremely hot ash cloud. Such a superheated cloud could have caused the bodies to become extremely hot before rapidly cooling when the cloud dispersed.
It is unusual for glass to form naturally. For a liquid to become glass, it must be cooled extremely rapidly, and the temperature of the solidifying material must be significantly higher than the surrounding temperature.
For organic material, which contains a lot of water, this is even more difficult, as water normally freezes at much lower temperatures than required for glass formation.
