"The glass formed as a result of this process allowed for an integral preservation of the biological brain material and its microstructures," said forensic anthropologist Pier Paolo Petrone of the University of Napoli Federico II in Italy, one of the leaders of the research published in the journal Scientific Reports.
"As the postures of the victims' bodies show, the custodian of the college died instantly from the impact with the hot volcanic ash surge, as did all the rest of the inhabitants of Herculaneum," Petrone said.
They say the vitrification - transformation into glass - of the victim's brain happened when a scorching ash cloud suddenly descended upon his city along the Bay of Naples, instantly killing all the inhabitants.
"Taking one of these fragments, it had a black appearance and shiny surfaces quite similar to obsidian, a natural glass of volcanic origin - black and shiny, whose formation is due to the very rapid cooling of the lava.
Analyses of this material, previously published in other scientific journals, revealed the presence of proteins and fatty acids common in human brain tissues, with the entire central nervous system exceptionally well preserved, represented by nerve cells interconnected by a dense network of fibers called axons.
