The earliest known iron beads may come from ancient Egyptian tombs, but they were forged from the hearts of meteorites, scientists say.
The findings, published in the Journal of Archaeological Science, show that humans might have begun working with iron from space long before they managed to unlock iron in the Earth.
The beads were excavated in 1911 from separate tombs of two teen boys in a cemetery in Gerzeh, in northern Egypt. Nine strange iron beads among their precious contents were parceled out to museums around Europe that had helped fund the expedition.
"The beads predate the emergence of iron smelting by nearly 2000 years, and other known meteoritic iron artefacts by more than 1000 years, giving them an exceptional position in the history of metal use," the authors wrote.
Here's the thing about these beads. By all rights, they shouldn't really exist. The nine beads — seven from one teen's tomb, two from another — are about 5,000 years old, dated to around 3200 BC. Somehow they were created about 2,000 years earlier than the onset of the Iron Age, when humans began regularly working with iron to make tools.
"Iron is referred to as the democratic metal, because every society could have access to it," said lead author Thilo Rehren, an archaeometallurgist at University College London Qatar in Doha.
Copper was rarer, but it had one key advantage: With a 2,000 degree Fahrenheit melting point, it was easier to pull out of its rocky ore form. Iron, on the other hand, would require an oven of about 2,800 degrees. This was far beyond blacksmith technology around the dawn of the Bronze Age, when these artifacts were made.
So where could these clearly worked iron beads appear at the dawn of the Bronze Age, millenniums before iron stole the scene?
Researchers have suggested the metal in such beads came from meteorites, judging by their surface composition. Rehren and his colleagues looked deeper, bombarding their beads with neutrons to study their interiors. Unlike iron smelted on Earth, meteoric iron has a small fraction of nickel, around 5% to 10%. That, combined with signature amounts of other trace elements, told them the iron in the beads came from a space rock.
Now that they could look inside the badly corroded beads, the researchers also discovered their surprisingly delicate, coiled internal structure. The smiths must have had to repeatedly heat and beat the metal into a thin sheet before rolling it into a bead — much harder than drilling a hole straight through.
"That shows these people, 5,000 years ago, were capable of proper smithing," he said, "which is a much more sophisticated process."
Thanks to these gifts from outer space, some blacksmiths of ancient Egypt must have grown comfortable working with iron long before humans could pull it from the rocks themselves.
"It would have helped to kick-start the transition" from Bronze Age to Iron Age, Rehren said. "When finally, at the end of the Bronze Age, people invented iron smelting ... they had already the knowledge handed down from generation to generation," he explained.
It's unclear why the Egyptians would have bothered working with this metal before the dawn of the Iron Age. Egyptian texts a millennium after these beads were made referred to "metal from the sky," which historians have taken to mean meteoritic iron.
And the Russian meteor that streaked over Siberia earlier this year came in with quite a bang, Rehren noted, so perhaps the source of this strange metal was patently obvious at the time.
Perhaps the metal had picked up some value or meaning. The tomb of King Tutankhamen, who died in 1323 BC, included a dagger possibly made with meteoritic iron.
"It was still good enough for a pharaoh," Rehren said.
In any case, why these beads cropped up at just two of the hundreds of tombs explored at Gerzeh also remains a mystery, as does the story of the two teens who owned them. One boy had some of his seven beads strung into jewelry; the other had collected a wide range of valuable stones and odd knickknacks, from lapis lazuli from Afghanistan to a lump of plant resin.
These youths were probably just like kids today who go off to summer camp and return home with pockets full of collected oddities, Rehren said.
"These two boys seem to have been collecting weird and wonderful things," Rehren said. "I think it's kind of sad these boys died as young as they did, because I can see them growing up as early kind of scientists — maybe making discoveries they would pass on to their children."
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