Copper Coin Placed in a Buried Baby’s Hand 150 Years Ago Accidentally Mummified It Into a Green Relic

A grieving mother’s desperate ritual sparked an accidental copper-based mummification.

When the anthropologist János Balázs opened a storage box from a Hungarian cemetery excavation, he found bones so small he initially mistook them for a rat’s. But among the fragile ribs and vertebrae lay a tiny human forearm, stained a distinct shade of green. Even stranger, the right hand hadn’t decayed with the rest of the skeleton; its flesh and curled fingers remained completely intact, preserved as a natural mummy.

This macabre relic is one of the first documented instances of pure copper-driven mummification, a rare preservation case that appears to have resulted from unusually high local copper exposure.

Upon closer investigation, biological anthropologists discovered that an antimicrobial reaction from a 19th-century coin naturally preserved the infant’s hand for over a century, an unintended result of a last homage.

A Forgotten Box of Bones

The initial excavations took place two decades ago, around the year 2005, near Nyárlőrinc, a village in southern Hungary. Archaeologists unearthed more than 500 graves from an abandoned cemetery dating from roughly the 12th to 16th centuries. More than a decade later, Dr. Balázs and his colleague Zoltán Bölkei began examining the forgotten remains stored in the local archives.

It was then that they came across the tiny mummified hand and green skeleton, presumed to belong to a premature infant or a stillborn baby. The child weighed no more than 900 grams (1.98 lbs) and measured a mere 28 to 33 centimeters (11 to 13 inches) long.. The bones exhibited no signs of disease.

Archaeologists occasionally find green-tinted bones at grave sites. As bronze or copper jewelry degrades in the earth, it leaches colored compounds into the surrounding soil and skeleton. Dr. Balázs suspected the child’s body had come into contact with metal. But in this case, finding the source of that metal, proved more challenging than at first glance.

“It’s not so obvious, and it’s so unlikely that you’re questioning yourself,” Dr. Balázs said, according to The New York Times.

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Copper Levels Over the Chart

To better understand the bizarre coloration, the researchers performed detailed chemical analyses of the remains. The infant’s body harbored copper concentrations nearly 500 times higher than average. According to the scientists, these were among the most extreme copper enrichments reported for human remains in this context.

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The sheer volume of the metal demanded an explanation. Dr. Balázs searched the collections at Hungary’s Móra Ferenc Museum, seeking out other storage boxes from the exact burial site. Among the cataloged artifacts, he found the missing pieces of the puzzle: a shattered ceramic pot and a heavily corroded copper coin.

The coin fit perfectly into the infant’s tiny, mummified hand.

“We started to see the actual story unfold,” Dr. Zsolt Bereczki, co-author of the study, said.

Accidental Preservation

Under normal circumstances, soft tissue decays rapidly. Microbes quickly break down flesh, leaving only bone behind. Natural mummification usually requires extreme environments, like freezing glaciers or parched deserts.

The earth in southern Hungary offered none of these conditions. The bodies buried nearby had decayed completely. But copper possesses powerful antimicrobial properties. It essentially poisons the bacteria and fungi responsible for decomposition.

As the coin oxidized in the damp earth, it flooded the child’s hand with copper ions. The near-closed ceramic vessel likely created a moist, relatively isolated microenvironment that allowed copper from the coin to diffuse through nearby tissues and slow decay. Because the child was likely placed in a tight, crouched position, the copper corrosion seeped through the tiny body, staining the hip, legs, and back.

Other historical figures have experienced partial preservation from metal artifacts. In 1959, archaeologists discovered a mummified lung inside the sarcophagus of the sixth-century French Queen Arnegunde, likely caused by a copper belt reacting with embalming fluids. Some Siberian mummies found in 2002 wore copper face masks.

However, the Nyárlőrinc infant stands alone. Researchers believe this is the first documented case in scientific literature where mummification was driven solely by copper.

Since these findings were first revealed in 2016, researchers have discovered an adolescent boy buried around three centuries ago in a copper box in northern Italy. In 2025, they reported that these remains in Italy represent the near-complete green mummy ever known. Apart from its left leg, it is almost entirely green from skin to bone.

A Mother’s Secret Toll

The copper coin clenched in the baby’s hand was a “Kreuzer”—or “krajcár”—minted between 1858 and 1862. In other words, the child was not buried in the original medieval cemetery. By that time the cemetery would have been abandoned for over 150 years. Furthermore, Christians in the 19th century did not traditionally bury their dead with coins.

The researchers realized they were looking at a desperate, clandestine act. Because the child died prematurely, it was never baptized. Denied a place in consecrated ground, the grieving family likely snuck into the abandoned cemetery at the edge of town.

Following an ancient, unrecorded folk tradition, someone—perhaps the mother—pressed the low-value copper coin into the baby’s hand. The coin served as a mythical toll, meant to pay Saint John the Baptist for a heavenly christening. They sealed the child inside the pot and buried it in secret.

The researchers found evidence of two other premature infants buried in similar pots nearby. One had a coin and green bones, but the tissue had decayed. The other had no coin at all.

The folk ritual was intended to secure safe passage for the unbaptized infant in the afterlife. Through an unintended chemical reaction, the infant achieved a different kind of immortality.

“They kind of succeeded at saving not necessarily the soul, but some kind of legacy of this little kid,” Dr. Bereczki said, “because here we are still talking about the baby and the circumstances of its burial 150 years later.”

The study was published in the journal Archaeological and Anthropological Sciences.