In A.D. 79, a man who died in Mount Vesuvius' eruption near Pompeii had a rare transformation: His brain seemingly turned into glass. But scientists have long debated how it happened, because the pyroclastic flows of rock fragments, ash and gas that buried him would not have been hot enough, nor cooled quickly enough, to "glassify" or vitrify the man's brain.
Now, researchers have proposed a new explanation: the pyroclastic flows must have been immediately preceded by a superheated cloud of ash that first rapidly heated and then rapidly cooled the man's brain as it dissipated, turning it to glass.
