In Vesuvius, a Human Brain Turned Into Stunning Glass

They are tiny pieces of black glass. They are also, technically, fossilized brains. The pea-sized pieces of shiny glass, actually quite beautiful close up, were discovered around 2018 inside the skull of a man who died when Italy's Mount Vesuvius erupted in 79AD, destroying Roman cities including Herculaneum and Pompeii, per the BBC. Researchers suspected the man's brain was vitrified, but they weren't quite sure how. Glass can occur naturally when sand or rocks are heated to high temperatures and quickly cooled, but it's rare. Indeed, the researchers who concluded vitrification did occur say this is one of only a handful of cases of any organic material undergoing the process, and the only known case of human or animal remains transforming into glass.

As with Herculaneum's other residents, the man discovered in the 1960s in his bed in the city's College of the Augustales, believed to be the college's custodian, was already dead when an avalanche of volcanic material buried the city. This study, published Thursday in Scientific Reports, offers further evidence that a scorching ash cloud came first. Researchers concluded the cloud was at least 950 degrees Fahrenheit, and perhaps as hot as 1,100 degrees, when it turned the custodian's brain into a liquid that cooled and solidified fast enough to prevent crystallization, perhaps the result of the ash cloud quickly dissipating. Researchers say the pyroclastic flow that later buried the city wasn't quite as hot and would've cooled too slowly for vitrification, per CNN.

Though there are doubters, study author Pier Paolo Petrone, a forensic anthropologist at the University of Naples Federico II, says he's convinced the glass started out as a brain because "brain material" including "proteins expressed in human brain, and of fatty acids found in human hair" is preserved, per the Guardian. "The only other type of organic glass we have evidence of is that produced in some rare cases of vitrification of wood" in Herculaneum and Pompeii, he adds. No other part of the man's body was vitrified. His organs "were likely destroyed by the heat before they could cool down enough to turn to glass," per the BBC. Lead study author Guido Giordano, a volcanologist at Roma Tre University, tells the outlet that "the very specific conditions that we have reconstructed for the vitrification of the brain make it very difficult for there to be other similar remains." (More discoveries stories.)