Photograph by Gianluca Miniaci, Petrie Museum of Egyptian Archaeology
Published August 22, 2013
After a century of uncertainty, researchers have confirmed that the iron used to weld 5,000-year-old Egyptian beads fell from the sky—in the form of a meteorite, that is.
The nine small beads were excavated in 1911 from a tomb in Gerzeh, an ancient cemetery in northern Egypt. Early chemical testing showed traces of nickel, leading scientists to believe they were made from meteoric iron.
The beads were prized as exotic artifacts, strung together on a necklace with precious minerals like gold and carnelian. (Related: "Oldest North American Rock Art May Be 14,800 Years Old.")
Fast forward a few decades to the 1980s, when a fragment from the beads was retested to determine its composition using newer technology called an electron microprobe. The results revealed concentrations of nickel that were too low to confirm whether the iron came from a meteorite.
Still, some scientists remained unconvinced that the beads were entirely man-made, which was an alternative explanation.
Thilo Rehren, a professor at University College London's Institute of Archaeology campus in Qatar, released a study in the Journal of Archaeological Science on Tuesday that says germanium levels—a chemical element not highly concentrated in man-made iron—prove the metal is meteoric.
Using noninvasive neutron and x-ray methods, Rehren and his team tested the inner core of the beads where the original metal was before it corroded. In the 1980 study that found low levels of nickel, scientists only were able to test the bead's outer layer, which had crusted into pure iron rust over time. (Related: "Giant Maya Carvings Found in Guatemala.")
"The label for these beads said: 'Meteoric Iron, question mark,' but with this new research we could say, 'Meteoric Iron, exclamation mark!'" Rehren said.
A Sign of Ancient Welding
In addition to being the oldest discovered artifacts made from meteoric iron, these beads provide novel insight into Egyptian civilization that predates the Iron Age by 2,000 years.
Rehren says the beads are the earliest known sign of metalwork, suggesting that people at that time had already mastered the art of blacksmithing. (See: "Egypt Mummy Pictures: Scans Show Ancient Heart Disease.")
The beads were created from rolling a very thin sheet of metal into a tube. Because meteoric iron is as tough as stainless steel, the process is precise. The brittle iron must be cooled extremely slowly to make sure it does not crack. Once the beads are heated, they are hammered into their nugget-like form.
"You don't always need to have Indiana Jones go out and dig up a new palace or temple," Rehren said.
"It is fascinating to see what museum collections still yield in terms of new information and discoveries."
Follow Jaclyn Skurie on Twitter.
From impossibly fuzzy chicks to superfast divers, see some of our favorite National Geographic pictures of penguins in action.
Fish are easy pickings after this slow-moving predator blasts them with a cloud of insulin.
A grueling trek through a jungle, followed by a treacherous climb: How one team took on one of mountaineering's biggest tests.
The Future of Food
How do we feed nine billion people by 2050, and how do we do so sustainably?
We've made our magazine's best stories about the future of food available in a free iPad app.