Iron from space helps determine the age of one of Spain’s greatest treasures

One of the most important and mysterious discoveries of the Bronze Age appears to have involved meteoritic iron. The discovery could clear up confusion about the age of not only the iron objects, but also the wealth of gold they were buried with.

The Treasure of Villena was discovered in 1963 in what is now eastern Spain. The 59 bracelets, bowls and miscellaneous objects are best known for their wealth of gold, but the most intriguing aspect is the iron from which two of the objects are made. These were the oldest iron pieces found on the Iberian Peninsula and based on the associated riches they appeared to date back at least 3,000 years. The origins of the entire hoard are mysterious enough, given the lack of evidence of the civilization that created them, and the presence of what appear to be Bronze Age artifacts with the iron pieces deepens the mystery.

But long before humanity learned to mine and smelt iron, we used iron from meteorites found on the Earth’s surface. Most famously, Tutankhamun had a dagger forged from meteorite iron, and the young pharaoh’s possession of it demonstrated the enormous value placed on such objects. The ability to process the mix of iron, nickel and sometimes cobalt known as meteoritic iron must have developed independently in many places, as pre-Iron Age examples are found in North America, southern Africa and Tibet, as well as in Middle East. .

One iron piece is a hollow hemisphere partially covered in gold (also called a cap or pommel) and the other is a bracelet. Their purpose is unknown, but at first glance their existence indicates that the hoard must date from the Iron Age, even though it was the very beginning when ironwork was new enough to be very valuable. But if so, what do they do with so much Bronze Age gold?

The gold casing makes this item look a bit like the rest of the treasure, but when it was made, the iron protruding through it might have been more valuable. Maximum diameter 4.5 cm (1.8 inches).

Image credit: Photography Villena Museum (Alicante); Rovira-Llorens et al, Trabajos de Prehistoria 2023 (CC BY 4.0)

However, if the iron from which the two pieces are made comes from heaven and not from the earth, there would be no discrepancy.

Inevitably, archaeologists have wanted to test the iron pieces for a long time. However, the combination of corrosion that makes most old iron very delicate, and the desire to protect the objects from harmful testing methods, has been a hindrance. The increasing availability of non-destructive testing has changed the situation, leading retired museum curator Salvador Rovira-Llorens and co-authors to examine the composition of the pieces.

In our eyes, the open bracelet seems worthless compared to the rest, but scientifically speaking, its value is much higher.

To our eyes, the open bracelet looks crappy compared to the rest, but what a journey it has been on. Maximum diameter 8.5 cm (3.4 inches).

Image credit: Photography Villena Museum (Alicante); Rovira-Llorens et al, Trabajos de Prehistoria 2023 (CC BY 4.0)

Portable X-ray fluorescence spectrometry yielded uncertain results, so the team turned to mass spectrometry applied to small samples. They found that the proportion of nickel in the cap (5.5 percent) is very similar to that of known iron meteorites, and well above what is commonly found in terrestrial deposits. On the other hand, preliminary measurements of the bracelet gave the clearly ambiguous result of 2.8 percent.

Corrosion can cause more nickel to leach than iron, reducing its concentration. Further analysis revealed more nickel in the interior areas that were less exposed to air and water, indicating that the bracelet was also made of meteoritic iron. Indeed, it is likely that it was from the same meteorite, the uncorroded composition being the same. However, matching the composition to a specific meteorite has not been possible until now.

“The available data suggest that the cap and bracelet from the Villena Treasure would currently be the first two pieces attributable to meteoritic iron in the Iberian Peninsula, which is compatible with a Late Bronze chronology, before the beginning of the widespread production of terrestrial iron,” the authors write.

Outside Greenland, almost all terrestrial iron is in the form of iron oxide, which Bronze Age people did not have the technology to reduce. Not only did meteorites avoid the need for this, but the iron-nickel alloys were more resistant to corrosion even when pure iron became available. The immensely rare product was the Earth equivalent of Valyrian steel in Westeros, which took on enormous value due to its extreme rarity.

The study was published in Trabajos de Prehistoria.

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