A new analysis of ancient Egyptian iron beads found in 1911 in Gerzeh, northern Egypt, has shown that they were hammered from pieces of meteorites, rather than iron ore.

Carefully hammered into thin sheets before being rolled into tubes, the nine beads were originally strung into a necklace together with other exotic minerals such as gold and gemstones, revealing the high value of this exotic material in ancient times.

“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,” explained Prof Thilo Rehren from the Hamad bin Khalifa University in Qatar, who is a lead author of the paper published in the Journal of Archaeological Science.

The results show that in the 4th millennium BC metalworkers had already mastered the smithing of meteoritic iron, an iron-nickel alloy much harder and more brittle than the more commonly worked copper, developing techniques that went on to define the Iron Age.

As a result metalworkers had already nearly 2,000 years of experience of working with meteoritic iron when iron smelting was introduced in the mid-second millennium BC. This knowledge was essential for the development of iron smelting and the production of iron from iron ore, enabling iron to replace copper and bronze as the main metals used.

Prof Rehren and his colleagues used x-ray methods to determine whether the 5,000-year-old beads were actually meteoric iron, and not magnetite, which can often be mistaken to be corroded iron due to similar properties.

By scanning the beads with beam of neutrons and gamma-rays, the scientists were able to reveal the unique texture and also high concentration of nickel, cobalt, phosphorous and germanium – which is only found in trace amounts in iron derived from ore – that is characteristics of meteoric iron, without having to attempt invasive analysis which could potentially damage these rare objects.

“The really exciting outcome of this research is that we were for the first time able to demonstrate conclusively that there are typical trace elements such as cobalt and germanium present in these beads, at levels that only occur in meteoritic iron,” Prof Rehren explained.

“We are also excited to be able to see the internal structure of the beads, revealing how they were rolled and hammered into form. This is very different technology from the usual stone bead drilling, and shows quite an advanced understanding of how the metal smiths worked this rather difficult material.”

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Bibliographic information: Thilo Rehrena et al. 5,000 years old Egyptian iron beads made from hammered meteoritic iron. Journal of Archaeological Science, published online August 20, 2013; doi: 10.1016/j.jas.2013.06.002