Volcanic ash cloud turned brain to glass

By 2025-06-13T06:56:00

A piece of black glass in an odd shape

Source: © Pier Paolo Petrone

Explore changes of state with this real-life horrible history

Scientists have discovered a nearly 2000 year-old brain that has turned to glass in the Roman town of Herculaneum. This unique example of natural vitrification of soft tissue occurred due to rapid heating, caused by a hot ash cloud in the wake of the eruption of Mount Vesuvius, followed by quick cooling. The skull likely protected the brain, while other body parts didn’t vitrify. Use this gruesome story and accompanying slide to engage your 14–16 learners when studying changes of state.

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