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Among the cache of glittering golden treasures of the Iberian Bronze Age, a pair of rusted objects may prove to be the most valuable of all.
A blunt bracelet and a rusty hollow hemisphere, decorated with gold, were forged, as the researchers found out, not from metal from the ground, but from the iron of meteorites that fell from the sky.
The discovery, made by Salvador Rovira-Llorens, now retired head of conservation at the National Archaeological Museum of Spain, was made public in articles, published in January, and suggests that metalworking technologies and methods were much more advanced than we thought in Iberia more than 3 years ago.
Viljena's treasure, as they call the hiding place from 66 mostly gold objects, was found more than 60 years ago, in 1963, in what is now the city of Alicante in Spain, and has since been considered one of the most important examples of Bronze Age jewelry in the Iberian Peninsula and throughout Europe.
However, determining the age of the collection was somewhat difficult due to two items: a small hollow hemisphere believed to be part of a scepter or sword hilt, and a single torc-like bracelet that resembles a torc. Both have what archaeologists describe as an "iron" appearance - meaning they appear to be made of iron.
In the Iberian Peninsula, the Iron Age - when iron smelted in the earth began to replace bronze - did not begin until about 850 BC. The problem is that the gold materials have been dated between 1500 and 1200 BC. So figuring out the location of the iron-looking artifacts in the context of the Viljena treasure was something of a puzzle.
But iron ore in the earth's crust is not the only source of malleable iron. Around the world there are a number of pre-Iron Age iron artifacts that were forged from meteorite debris. Perhaps the most famous is the pharaoh Tutankhamun's meteoric iron dagger, but there are other Bronze Age weapons made from this material, and they were very highly valued.
There is a way to tell the difference: iron from meteorites has a much higher nickel content than iron mined from Earth's soil. Therefore, the researchers received permission from the Municipal Archaeological Museum of Villena, where the collection is kept, to thoroughly test both artifacts and determine exactly how much nickel they contain.
They carefully sampled both artifacts and subjected the material to mass spectrometry to determine their composition. Despite the high degree of corrosion, which changes the elemental composition of the artifact, the results strongly suggest that both the hemisphere and the bracelet were made of meteoric iron.
This neatly resolves the dilemma of how these two artifacts fit in with the rest of the collection: they were made around the same time period, dating to around 1400-1200 BC.
"Available evidence suggests that the cap and bracelet from the Villena hoard are today the first two objects associated with meteoric iron in the Iberian Peninsula," the researchers explain in their paper, "which is compatible with the chronology of the Late Bronze Age, before the beginning of large-scale production of terrestrial iron".
Currently, due to the fact that the objects are very badly damaged by corrosion, the results are not final. But there are more modern, non-invasive methods that can be applied to the objects to obtain a more detailed set of data that will help solidify the conclusions, the team suggests.
