The detection of the cosmogenic isotope aluminum-26; the concentrations of nickel, cobalt, germanium and gallium; and the presence of two minerals called kamacite and taenite unambiguously demonstrate the meteoritic nature of the ancient arrowhead from the Bronze Age settlement of Mörigen, Switzerland.
“Metallic iron was available to humans in the form of rare meteoritic iron before the smelting of the metal from oxide ores started,” said lead author Dr. Beda Hofmann, a researcher at the Naturhistorisches Museum Bern and the University of Bern, and colleagues.
“The use of meteoritic iron for the fabrication of objects in pre-Iron Age times in Eurasia and northern Africa is known from find complexes in Turkey, Greece, Syria, Iraq, Lebanon, Egypt, Iran, Siberia and China.”
“Finds of meteoritic iron artifacts in central and western Europe are very rare and up to now were restricted to two sites in Poland: the two Czestochowa-Rakowa bracelets and the Wietrzno axe.”
In their research, the archaeologists examined an unusual iron arrowhead from the collections of the Bern History Museum.
The artifact was found in the 19th century at the Late Bronze Age lake dwelling site of Mörigen in Switzerland.
“The Mörigen pile dwelling was known since 1843, first sampled by fishermen and excavated 1873-1874,” the researchers said.
“The site is located just 4-8 km southwest of the large Twannberg iron meteorite strewn field with more than 2,000 individual finds totaling 150 kg.”
The Mörigen arrowhead has a mass of 2.9 g and dimensions of 3.9 cm (length), 2.5 cm (width) and 0.3 cm (maximum thickness).
The object consists of rust-covered iron metal with a very pronounced laminated texture. In some areas, fine-grained sediment is attached.
“The arrowhead is a very flat object (aspect ratio 15.1, after correction for thickness increase due to oxidation 20),” the scientists said.
“Primary shapes of meteoritic iron are never as flat, even in case of ‘shrapnels’ (fragments formed due to explosive disruption on impact).”
“The flat aspect of the object must be due to artificial deformation of an originally less flattened object, either due to cold or hot working.”
The authors studied the Mörigen arrowhead using a combination of several exclusively non-destructive methods, including muon-induced X-ray emission spectrometry and high-sensitivity gamma spectrometry.
The elemental composition (7.10-8.28 wt% nickel, 0.58-0.86 wt% cobalt, 300 ppm germanium), the presence of nickel-poor and nickel-rich iron phases kamacite (6.7 wt% nickel) and taenite (33.3 wt% nickel), as well as the presence of cosmogenic aluminum-26 confirmed the meteoritic origin of the artifact.
They were also surprised to find that the Mörigen metal came not from the nearby Twannberg iron meteorite strewn field.
“The Mörigen arrowhead must be derived from a large (minimum 2 tons pre-atmospheric mass) IAB iron meteorite based on gamma spectrometry and elemental composition,” they said.
“Among large IAB meteorites from Europe, three have a chemical composition consistent with the Mörigen arrowhead: Bohumilitz (Czech Republic), Retuerte de Bullaque (Spain) and Kaalijarv (Estonia).”
“Kaalijarv is a large meteorite that produced a series of impact craters on the island of Saarema in Estonia.”
“As a result of the explosive impact, most of the meteorite mass (probably several 100 tons) was destroyed and recovered meteorite fragments are mostly small ‘shrapnels’ resulting from the destruction of the main mass.”
“Such a small fragment may be the source of the arrowhead, but detachment from larger masses is also possible, as is well documented for the Cape York meteorite.”
“The total recovered mass of Kaalijarv is in the order of 10 kg only,” they added.
“Based on three independent studies of organic materials from the base of lake sediments and below ejecta, the impact most likely occurred between 1870 and 1440 BCE, i.e. during the Bronze Age.”
The discovery demonstrates that iron meteorites were used and traded by 800 BCE, or even earlier, in Europe.
“Fragments of the Kaalijarv meteorite may have been traded over the same routes from the Baltic area as amber,” the archaeologists said.
Their paper will be published in the September 2023 issue of the Journal of Archaeological Science.
Beda A. Hofmann et al. 2023. An arrowhead made of meteoritic iron from the late Bronze Age settlement of Mörigen, Switzerland and its possible source. Journal of Archaeological Science 157: 105827; doi: 10.1016/j.jas.2023.105827