An arrowhead made of meteoritic iron from the late Bronze Age settlement of Mo & BULL;rigen, Switzerland and its possible source

A search for artefacts made of meteoritic iron has been performed in archaeological collections in the greater area of the Lake of Biel, Switzerland. A single object made of meteoritic iron has been identified, an arrowhead with a mass of 2.9 g found in the 19th Century in the late Bronze Age (900-800 BCE) lake dwelling of Mo & BULL;rigen, Switzerland. The meteoritic origin is definitely proven by combining methods extended and newly applied to an archaeological artefact. Elemental composition (7.10-8.28 wt% Ni, 0.58-0.86 wt% Co,-300 ppm Ge), primary mineralogy consisting of the associated Ni-poor and Ni-rich iron phases kamacite (6.7 wt% Ni) and taenite (33.3 wt% Ni), and the presence of cosmogenic 26Al (1.7+0.5 0.4 dpm/kg). The Ni-rich composition below the oxidized crust and the marked difference to meteorites from the nearby (4-8 km) Twannberg iron meteorite strewn field is confirmed by muon induced X-ray emission spectrometry (8.28 wt% Ni). The Ni-Ge-concentrations are consistent with IAB iron meteorites, but not with the Twannberg meteorite (4.5 wt% Ni, 49 ppm Ge). The measured activity of 26Al indicates derivation from an iron meteorite with a large (2 t minimum) pre-atmospheric mass. The flat arrowhead shows a laminated texture most likely representing a deformed Widmansta & BULL;tten pattern, grinding marks on the surface and remnants of wood-tar. Among just three large European IAB iron meteorites with fitting chemical composition, the Kaalijarv meteorite (Estonia) is the most likely source because this large crater forming fall event happened at-1500 years BC during the Bronze Age and produced many small fragments. The discovery and subsequent transport/trade of such small iron fragments appears much more likely than in case of buried large meteorite masses. Additional artefacts of the same origin may be present in archaeological collections.