Research Shows How Mount Vesuvius Turned Man’s Brain Into Glass 

A team of Italian and German scientists recently determined how the brain of a victim of Mount Vesuvius’s 79 CE eruption managed to be preserved through its conversion into organic glass. Regarded as the first and only known organic glass sample to contain human brain matter, the shiny black material was recovered from inside the skull of an approximately 20-year-old man from Herculaneum, a smaller city northwest of Pompeii that was also destroyed by the volcano.

The researchers published the results of an initial sample examination in the New England Journal of Medicine in 2020, identifying several proteins and fatty acids prevalent throughout cerebral tissue and human hair fat. This was followed by a secondary report outlining the remarkable preservation of the individual’s central nervous system.

“As with the discovery of the vitrified brain, this finding was something never before seen at such a level of detail,” Pier Paolo Petrone, a forensic biologist and archaeologist with the University of Naples Federico II and contributing researcher, told Hyperallergic in an email.

It’s rare for archaeologists to find such well-preserved neural matter due to its molecular makeup, but the question of how the Herculaneum man’s brain became the only known example preserved through vitrification went unanswered until the researchers published their latest report on February 27.

Petrone and his team determined that the 20-year-old man, who died on his wooden bed inside a building known as the Collegium Augustalium in Herculaneum, was exposed to an extremely hot and rapidly moving pyroclastic flow that swept through the city, since the vitrification process requires fast heating followed by exceptionally fast cooling. The report implies that the individual’s brain was protected from complete thermal decomposition and subsequently vitrified due to the skull’s thicker bones, which afforded protection from the hot ash cloud.

Per the report, the brain vitrified at temperatures above 950°F (510°C), therefore establishing that an initial high-temperature ash cloud enveloped the man and liquified his brain before settling as a deposit within minutes, almost instantly returning the temperature to ambient conditions. With only a few centimeters of ash settling from the initial cloud, the bodies of the individual and hundreds of others were left in open air to be slowly buried in low-temperature ash and pumice deposits across the city, allowing the man’s liquified brain to cool quickly and complete its transition into glass.

“As the material is totally rare and in no other way obtainable, the selected samples remain available for further studies, as only a small part of what can be investigated has been done, pending further and deeper analysis,” Petrone clarified to Hyperallergic with regard to the unique sample. “It’s the very first time in the world of such an exceptional and unique discovery.”

Petrone noted that while the vitrified brain matter will remain in scholarly hands for the time being, the discovery site of the carbonized individual from which the sample was recovered will be accessible to visitors in the near future.