'Green mummy' reveals copper’s surprising role in preservation

A young boy laid to rest three centuries ago in northern Italy has become a scientific first: the only nearly complete “green mummy” ever documented.

Archaeologists discovered the boy’s copper-box tomb in 1987 beneath an ancient villa in Bologna, revealing remains preserved from skin to bone in vivid green.

New analyses reveal how a rare combination of metal, chemistry, and microclimate transformed a routine burial into an extraordinary natural experiment.

When copper stops time

Forensic work at the University of Bologna identified the body as that of a 12- to 14-year-old boy, later radiocarbon-dated to between 1617 and 1814.

Since its discovery, the mummy has remained carefully conserved until a broad team re-examined it with modern tools.

Geneticists, anthropologists, radiologists, mathematicians, physicists, computer scientists, and conservation scientists joined forces – a remarkable multidisciplinary collaboration.

Copper turned the mummy green

The lead-up to the mummy’s emerald hue began the moment the coffin was sealed. Copper is famously antimicrobial, so the box itself helped suppress the usual bloom of bacteria and slowed the mummy’s decay.

But the metal also corroded as organic acids seeped from the body, generating mobile copper compounds that permeated soft tissue and bone.

Over time, copper ions substituted for calcium in the skeleton, effectively “mineral-editing” the mummy’s bones while tinting them green.

On the surface, a crust of corrosion – true patina – formed as copper reacted with water and carbon dioxide. These gases were released during decomposition, coating the skin with the same pale-green film seen on weathered bronze statues.

The role of heavy metals

The result is not the patchy green sometimes seen when a coin or bracelet stains a nearby hand or jaw. This is systemic. Apart from the left leg, the body is almost entirely green from epidermis to marrow.

The mechanism is simple but relentless: ion exchange locks copper into the hard tissues, while patina sheets across the soft tissues.

“This completely changes our point of view on the role of heavy metals, as their effects on preservation are more complex than we might expect,” Annamaria Alabiso, a conservation scientist at the University of Rome Tor Vergata, told New Scientist.

The coffin’s environment amplified the effect. As acids accumulated, the base of the copper box beneath the mummy eventually cracked, allowing fluids to drain.

With the liquid gone, the chamber stayed cool, dry, and oxygen-poor – conditions that dramatically slow decomposition. The same episode likely explains the missing feet, which may have detached and been lost when the box failed.

The mummy that redefined metal

Mummified body parts with a copper tint are known – most famously a medieval infant’s hand, stained green by a coin in a jar. But a nearly complete green mummy is unprecedented.

That status elevates the boy from an unusual find to a reference specimen for understanding how metals reshape human remains over centuries.

The team’s array of chemical and physical assays traces each step: copper corrosion products migrating into tissue, calcium increasingly displaced in bone, and patina consolidating on skin.

Radiocarbon dating places the death in the early modern era. The absence of trauma or disease points to preservation, not pathology, as the story here.

That clarity impressed outside experts. The aesthetics are undeniable. But so is the forensics. The evidence strongly substantiates the argument regarding both the preservation and coloration of the tissue and bone.

Metal’s double life in mummies

The implications extend beyond a single coffin. Conservationists often treat metals as either threats (corrosion, staining) or aids (antimicrobial barriers).

This case shows they can be both – first suppressing microbes, then actively participating in chemical transformations that stabilize tissue and bone in unexpected ways.

It’s a reminder that burial environments write their own scripts. Soil chemistry, container materials, leaks, airflow, and temperature can all conspire to preserve or destroy in patterns we’d never see in the living body.

For archaeologists and curators, that means reassessing how copper and bronze objects in burials might have shaped the remains around them. It also means viewing those interactions as data rather than damage.

For historians of medicine and mortuary practice, it offers a rare window into early modern burial choices – why a copper box, and for whom? – and their unintended consequences.

A boy’s afterlife in green

Strip away the metrics and methods and what’s left is still a human story. An adolescent died.

His community sealed him in a copper coffin and set him beneath a villa. Centuries later, the chemistry of that choice returned him to view in a new palette.

Science can now explain the shades: copper guarding against rot, ions threading into bone, patina painting skin, and a cracked base turning a wet tomb into a dry vault.

What began as grief became, over time, a lesson in how matter remembers – and how the quiet details of burial can shape the afterlife of the body as surely as any ritual words.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–