Credit: A set design for the 1825 Pacini opera L’ultimo giorno di Pompei or “The Last Day of Pompeii,” which depicts the horrifying 79 C.E. eruption of the Mount Vesuvius volcano. Public domain image.

Mt Vesuvius erupted in 79 CE, killing thousands of people, and buried the city of Herculaneum in about 20 metres of volcanic debris, known as a pyroclastic flow deposit. Accompanying the debris were clouds of very hot gas, which then dissipated fairly quickly. According to the team’s 2020 publication, the victim in question was found lying on the charred remains of a wooden bed in a room which was part of a public building. The young person, who was probably male and aged at about 20 at the time of death, is believed to have been a guardian of the building, and his remains were excavated in the 1960s. What is unique about this individual, is that his brain and parts of his spinal cord underwent a process of vitrification (turning into glass) during the eruption. In their 2025 publication, the researchers explained that glass is formed when a hot liquid cools fast enough to prevent the formation of crystals. Organic tissues can be preserved as glass if cooled down, but usually revert back to their original state when heated up again, and then decompose. This is why no vitrified organic tissues are ever found. The vitrified brain tissue found inside the skull of the victim is the only example of organic material which has been preserved as glass known to science. Scientists have concluded that the victim was heated up to about 510°C by a cloud of hot gas and then cooled rapidly when the cloud dissipated. This provided the unique conditions for glass to form.

Credit: Glass in Skull – Pier Paolo Petrone-ABC News

After scanning the black, shiny fragments in a Scanning Electron Microscope (SEM), the researchers found that the complex networks of axons, neurons, cell bodies even down to layers of membranes around the axons had turned to glass. They describe the central nervous system tissue as “frozen in its native condition”. It is rare for soft tissue to be recovered from archaeological sites.

From their study of this victim, scientists have added another piece to the sequence of events in Herculaneum that day.  Researchers can now confirm that a hot gas cloud enveloped the town first, killing most of the people. The subsequent metres of material which rained down on Herculaneum would have done so after most, if not all, of the inhabitants had perished. In addition to this, the research also provides information which could protect people in the event of a volcanic eruption. Provision of heat-proof shelter could allow people to survive the hot ash clouds and be rescued.

There are still many active volcanos on Earth. Mt Vesuvius was quite active in the twentieth century, with the last major eruption occurring in 1944, famously filmed by United States Army Air Force photographers during World War Two.

Interested in more things Roman?

Visit the newly reopened UNE Museum of Antiquities: https://www.une.edu.au/info-for/visitors/museums/museum-of-antiquities

For more information about the findings in Herculaneum, see:

Petrone, P., Pucci, P., Niola, M., Baxter, P. J., Fontanarosa, C., Giordano, G., Graziano, V., Sirano, F., & Amoresano, A. (2020). Heat-Induced Brain Vitrification from the Vesuvius Eruption in c.e. 79. The New England Journal of Medicine, 382(4), 383–384. https://doi.org/10.1056/NEJMc1909867

Giordano, G., Pensa, A., Vona, A. et al. Unique formation of organic glass from a human brain in the Vesuvius eruption of 79 CE. Sci Rep 15, 5955 (2025). https://doi.org/10.1038/s41598-025-88894-5

Petrone, P., Giordano, G., Vezzoli, E., Pensa, A., Castaldo, G., Graziano, V., Sirano, F., Capasso, E., Quaremba, G., Vona, A., Miano, M. G., Savino, S., & Niola, M. (2020). Preservation of neurons in an AD 79 vitrified human brain. PLoS One, 15(10)https://doi.org/10.1371/journal.pone.0240017

Phiddian, E. (28 February, 2025). Killer ash cloud from Mount Vesuvius eruption turned man’s brain to glass: study. ABC News. https://www.abc.net.au/news/science/2025-02-28/vesuvius-eruption-turned-victim-brain-to-glass/104983512

Eruption of Mt Vesuvius 1944 https://youtu.be/1bsmv6PyKs0?si=OP5Hcd4FrJ3veZau