Iron from single meteorite found in ancient Polish artefacts

Three iron age bracelets and a pin contain metal from a single meteorite that fell over southern Poland more than 2500 years ago, a new study reveals.

The discoveries also indicate that the value of meteoritic iron – once considered a heavenly ‘sky metal’ – had fallen sharply by this time, as iron could be smelted from common ores.

The authors analysed 26 iron artefacts – including jewellery, tools, spearheads and knives – recovered from early iron age graves at the ancient Raków and Mirów burial grounds, which are now both within the southern city of Częstochowa.¹ Their analysis used portable x-ray fluorescence, scanning electron microscopy and energy dispersive spectroscopy to determine the ratios of chemical elements they contained, followed by x-ray microtomography to reveal the structures of samples.

Study lead author Albert Jambon, an archaeometallurgist and professor emeritus at Sorbonne University in Paris, said the researchers found four of the objects — the bracelets and the pin — contained an iron alloy from a meteorite, which could be recognised by its distinctively high levels — greater than 15% — of the element nickel.

Such a high level of nickel is uncommon in meteorites, while a meteorite fall was a rare event in itself, ‘so the occurrence of two very rare events is more than unlikely’, he said. That meant it was probable that the iron in all four objects had come from a single meteorite that was witnessed when it fell and later recovered, he added.

The three bracelets were found at the Raków burial ground, putting it among the places where more artefacts made with meteoritic iron have been found than anywhere else.

Jambon has also studied² the use of meteoritic iron in other early objects, including the gold-hilted dagger from the tomb of King Tutankhamen. That research indicated that all iron used before the iron age had come from meteorites, and never from smelting ore.

Jambon and his colleagues want to find out more about the development of iron smelting in Poland and so the latest study helped eliminate objects with metal from meteorites. Meteoritic iron was considered a precious ‘metal from heaven’ by the ancient Egyptians, but by the time of the early iron age in Poland – roughly 1000 years later – it seems it was not so highly prized.

The four items analysed by Jambon and his colleagues had mixed the meteoritic iron with smelted iron, apparently to create a distinctive surface effect. ‘A nickel-rich iron alloy will be more resistant to oxidation than nickel-poor iron,’ he explained. ‘If you have bands of two different alloys, the less oxidised will look bright [and] the more oxidised will look black, making a pattern.’

Archaeological scientist Thilo Rehren, an expert on prehistoric metallurgy who was not involved in the study, said that it added ‘an interesting facet to our understanding of the use of meteoritic iron’.

But he said he was unconvinced that the process of mixing meteoritic iron and smelted iron was done only to achieve a decorative pattern. On the other hand, ‘we can’t exclude it either, since ancient craftspeople – and likely their customers – had a very keen eye for observing subtle differences in colour or appearance’, he said.