The unusual case of the green mummy has puzzled scientists for decades.
A teenager buried in Italy hundreds of years ago developed a distinct emerald glow, unusual for human remains.
Today, scientists say the secrets behind this unusual color have been revealed, and the discovery "completely changes" their understanding of the role of certain materials in the preservation process.
The teenager, who was 12–14 years old when he died, was first found in the basement of an ancient villa in Bologna, Italy, in 1987. He had been buried in a copper box, and his skeleton was almost complete, except for his legs.
Any mummy find is considered important for science, but this case was special: except for the left leg, the mummy was almost entirely green, from skin to bones.
The body has been carefully preserved at the University of Bologna since its first discovery. Now, a team of experts has uncovered the mysterious circumstances that caused the unusual color.
According to Annamaria Alabiso, a conservation scientist at the University of Rome Tor Vergata, radiocarbon dating showed that the teenager died between 1617 and 1814. Chemical and physical analyses showed no clear signs of illness or trauma, leaving the cause of death unclear.
The preserved skin was covered with a pale green layer, similar to that which develops on copper and bronze statues.
"This discovery completely changes our view on the role of heavy metals, as their effects on conservation are more complex than we might think," Alabiso told New Scientist.
It is suspected that the bottom of the copper box cracked at some point, allowing the liquid to escape. This created a cold, dry environment with limited oxygen, which enhanced the preservative effect. The teenager's legs may have been severed and lost when the box broke.
In the Journal of Cultural Heritage, the team wrote: “The green mummy of Bologna is the result of a unique combination of environmental factors: low temperatures in the cellar, limited oxygen inside the box, and the biocidal action of copper ions, which together contributed to the unusual mummification process.”
How does copper affect mummification?
Another case, of a baby buried with a copper coin, shows that copper can cause a green color to appear on parts of the body. Analysis showed that some parts of the body were green all the way down to the bones, including the forearm, several vertebrae, a pelvic bone, and the bones of the legs.
Copper levels in the mummy were hundreds of times higher than average, according to the researchers. Copper, although essential for some human enzymes, has antimicrobial properties and has been used for many years as a fungicide and bactericide.
However, the process of so-called "copper-induced quasi-natural mummification" had not been previously documented, and this may be the first reported case. /GazetaExpress/
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