The experts used neutron and gamma ray methods to confirm that three small beads used in jewellery, created around 3200 BC, were made from "meteoritic iron."
"Iron beads were strung into a necklace together with other exotic minerals such as lapis lazuli, gold and carnelian, revealing the status of meteoritic iron as a special material on a par with precious metal and gem stones," said the researchers in their article, published in the Journal of Archaeological Science.
Professor Thilo Rehren, lead author of the paper, said in a press release: “The shape of the beads was obtained by smithing and rolling, most likely involving multiple cycles of hammering, and not by the traditional stone-working techniques such as carving or drilling which were used for the other beads found in the same tomb.”
The three beads, each about 2cm long, from the collection of the Petrie Museum of Egyptian Archaeology in London, come from a set of nine similar beads buried in two sealed graves near the village of el-Gerzeh, 70km south of the Giza plain where the pyramids would be built hundreds of years later.
In 1911, nine tube-shaped beads were excavated from the ancient cemetery. Inside the tomb, which belonged to a teenage boy, the iron beads were strung together into a necklace alongside other exotic materials, including gold and gemstones. Early tests suggested they may have been made from meteorites, but could not be confirmed as there were no non-invasive methods available until now.
The modern methods of scanning found high concentrations of cobalt, phosphorous and germanium; these elements were present at levels that only occur in iron meteorites.
The X-ray technology also revealed that the beads had been hammered into thin sheets before being meticulously rolled into tubes, rather than treated like other precious stones that were worn after having holes drilled into them.
"This meteoritic iron, it's very hard material that you find in lumps, and yet here we see it in thin beads," Rehren said. "The real question is, how were they made?"