A team of scientists recently completed a study of prehistoric metal artifacts collected in Switzerland over the past couple of centuries, with a very clear purpose in mind. They were looking to see if any of these ancient artifacts might have been made from metal salvaged from meteorites, which have been hitting Earth for billions of years . Much to their delight, the Swiss researchers were able to identify one such object: a small, rusted Bronze Age iron arrowhead with a chemical and mineral composition that was undoubtedly not of earthly origin.
As a part of their search process, the team of Swiss scientists led by geologist Beda Hofmann from the National History Museum of Bern concentrated on pre-Iron Age artifacts taken from various sites close to Switzerland’s Lake of Biel region. The one iron arrowhead made from meteoritic metal they did find was excavated from a Late Bronze Age (900 to 700 BC) settlement known as Mörigen, from where it had been unearthed all the way back in the 19th century.
Finding the Meteorite Iron Arrow
The heavily rusted arrowhead was tiny, measuring just 1.5 inches (39.3 millimeters) in length and only one-tenth of an ounce (2.9 grams) in weight. It was covered with traces of pitch likely harvested from a birch tree, which would have been used to affix it to the shaft of a wooden arrow.
Notably, the small prehistoric community of Mörigen was constructed only five miles (eight kilometers) from Twannberg, the site of a large Bronze Age meteorite strike that left chunks of iron strewn across a large area. This meteorite hit the earth more than 10,000 years ago, before the end of the last Ice Age . Consequently Late Bronze Age settlements in the area, like the one at Mörigen, would have had ample opportunity to salvage these extraterrestrial metallic resources for their own use.
But as this new study revealed, sometimes the most obvious assumptions are not the correct ones.
An end cut from the Toluca iron meteorite. (H. Raab/ CC BY SA 3.0 )
Traveling Millions of Miles through Space, and a Thousand Miles More After That
Testing the artifact to determine its metallic composition, the Swiss scientists found all the telltale signatures of an iron object that would have once been journeying across the solar system. The arrowhead was made largely from iron and nickel, in a mixture consistent with a meteoric origin. It also contained traces of the radioactive isotope aluminum-26. The latter particle does not occur naturally on Earth, because it can only form in the zero-gravity vacuum of space.
At this point in their study, the scientists had discovered what they hoped and expected to find. But as they explain in an article about their study appearing in the Journal of Archaeological Science , after completing their analysis they determined that the metal used to make the arrowhead had traveled a longer distance to reach prehistoric Switzerland than they’d initially suspected.
Contrary to all expectations, the scientists discovered that the iron used to make the arrowhead had not been harvested from the nearby Twannberg debris field. Rather, it came from a meteorite that had hit the Earth somewhere else, one that featured a slightly different composition from the meteorite responsible for the Twannberg impact event.
The iron from the Mörigen arrowhead was delivered to the planet’s surface by a special class of space object known as an IAB meteorite, made of meteoric iron and silicate inclusions. Only three of these iron rocks are known have struck the Earth in Eurasia in ancient times, and they were found at three distant archaeological sites: Bohumilitz in Czechia, Retuerte de Bullaque in Spain, and Kaalijarv in Estonia.
One of nine meteorite craters near the village of Kaali, Estonia, from an impact most likely 1530–1450 BC. ( CC BY-SA 3.0 )
Based on the timing and characteristics of the meteorite’s impact, the Swiss scientists concluded that the metal for the arrowhead most likely came from Kaalijarv event in Estonia. The meteorite responsible for this impact crashed into the Earth around 1,500 BC, and left the nearby areas littered with modest-sized and diversely shaped fragments that would have been relatively easy to heat and reshape into small tools or weapons.
But this Estonian site is located in Northern Europe on the coast of the Baltic Sea, nearly 1,000 miles (1,600 kilometers) from the Bronze Age settlement at Mörigen. This fact offers clear evidence that a prehistoric trade network connected central Europe with other lands in distant locations, including those well to its north.
It should be noted that the iron from the arrowhead also matches the iron associated with the IAB meteorite strikes in Spain and Chechia. So while it most likely came from Estonia, this cannot be established with 100-percent certainty just yet.
But regardless of its source, other pre-Iron Age artifacts likely exist that would have come from the same source.
“Whether or not derived from Kaalijarv, the arrowhead most likely was not a singular object and likely other worked fragments of meteoritic iron, including samples of relatively small size, are present in archaeological collections in Europe and possibly even at larger distance,” the Swiss scientists wrote in their Journal of Archaeological Science article.
What is known for sure is that the Kaalijarv impact produced a huge quantity of workable metal chunks. So if it was the parent of the iron in the Mörigen arrowhead there would almost certainly be many other similar objects out there. And if they were frequently exchanged along prehistoric long-distance trade networks, they might show up in some far-off and truly surprising places.
Tracking the Bronze Age Trade in Meteorite Metals
Before humans learned how to extract iron from iron ore using high heat, iron from meteorites was the only available source of this hard and strong metal.
Iron delivered to Earth by meteorites would have been difficult to find. But Bronze Age people did manage to discover them and melt them down to make useful objects, including tools, weapons and jewelry.
Archaeologists have recovered a total of just 54 artifacts made from meteoric iron since the 19th century, at 21 different sites in Eurasia and North Africa. But these items have been found in eight different countries: Greece, Turkey, Iraq, Lebanon, Syria, Egypt, Russia and China. This list covers an impressive geographical range, and makes it certain that such items were passed around via long-distance trade in some instances.
There may very well be more of these artifacts hidden in private or public collections across the planet, and in future archaeological sites that have yet to be excavated. Such artifacts are likely to be found on every continent eventually, given that meteorites have been striking the Earth for so long and in all locations.
Top image: Overview of the Mörigen arrowhead. Source: Thomas Schüpbach/ Science Direct
By Nathan Falde
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