Meteoritic iron is very rare
Evidence of such early use of meteoritic iron is extremely rare. The arrowhead is owned by the Bernisches Historisches Museum, it is 39 millimeters long and weighs 2.9 grams and comes from a Bronze Age pile dwelling station near Mörigen on Lake Biel (900 to 800 BC). It was found there during excavations in the 19th century. In order not to damage the irreplaceable historical artefact, the analysis had to resort to non-destructive examination methods.
The art of making iron from ore has been around in Central Europe since the beginning of the Iron Age around 800 BC. proven. Before this time, the metal was considered extremely rare and valuable – it was only known from meteorites. Archaeological objects made of meteoritic iron are therefore extremely rare and were probably not used as commodities at one time. Only 55 such objects are known in all of Eurasia and Africa, and they come from 22 different sites. 19 objects alone come from the tomb of Pharaoh Tutankhamun in Egypt. However, only some of the artefacts have so far been examined using modern analytical methods.
New research methods for meteorites
The methods now used to analyze the arrowhead in Bern include light microscopy, scanning electron microscopy, X-ray tomography, X-ray fluorescence, muon-induced X-ray spectrometry (MIXE) and highly sensitive gamma spectrometry. “With gamma spectrometry, we can create a radioactive fingerprint of any sample and also find relatively short-lived isotopes,” says Prof. Dr. Marc Schumann from the University of Freiburg. “Some of these isotopes are only produced in space.” This includes what is known as aluminum-26, which Schumann and his team were able to find in the arrowhead. “We were thus able to provide unequivocal proof that the material is a meteorite that was exposed to cosmic radiation in space for a long time.”
Surprising research result
Surprisingly, however, this does not come from the nearby Twannberg meteorite strewn field in the Bernese Jura/Switzerland. With around 8.3 percent nickel, the content of this element in the arrowhead is almost twice as high as in the Twannberg meteorite. A high germanium content also shows that it is very likely an IAB type meteorite. Furthermore, the rather low concentration of aluminum-26 suggests that the sample came from the interior of a meteorite that originally had a mass of at least two tons.
There are only a few known large IAB iron meteorites in Europe. The most likely origin is the meteorite Kaalijarv, which was discovered around 1500 BC during the Bronze Age. in Estonia fell. The fall of this meteorite produced multiple craters up to 100 meters in diameter. Since the largest meteorite fragments exploded on the ground, many small fragments should have formed. Further analyzes in European archaeological collections could provide clues as to whether the trail of the arrowhead from Mörigen to Estonia can be confirmed.