“We noticed a cross-hatched texture present in places for both sides [of the dagger]suggesting Widmanstätten structure, typical of [an] octahedrite iron meteorite, ”Arai said. “That was our WOW moment.”
The Widmanstätten pattern (named for an Austrian mineralogist) is a remarkable effect present in some metallic meteorites that’s caused by how nickel is distributed throughout the objects. The pattern’s presence in Tutankhamun’s weapon indicates that the dagger was made from an octahedrite, the largest group of iron meteorites.
To verify what they were seeing in the elemental analysis, the team compared the pattern on Tut’s dagger with the pattern on the Japanese meteorite Shirahagi. Shirahagi was the source of the iron in some Japanese swords acquired by the Taisho Emperor. Octahedrites, apparently, are a favorite of monarchies everywhere.
The pattern’s presence in the ancient Egyptian dagger also hints at how it was made. The team wrote in their paper that the Widmanstätten pattern would disappear if the iron were heated to a very high temperature.
“We also found small black patches in places on the surface,” Arai said. “We thought they were rust at first. But it turns out that they were iron sulfide, which generally occur as inclusions in octahedrite iron meteorites. ”
Arai said that the presence of iron sulfide, as well as the subtle Widmanstätten pattern, indicates the dagger was forged with relatively low heat — less than 950 ° Celsius (1,742 ° Fahrenheit.)
Though the chemical analysis did not offer clues to the dagger’s origins, the team turned to a series of 3,400-year-old tablets known as the Amarna Letters, which document diplomatic activities in ancient Egypt in the mid-14th century BCE. The letters mention an iron dagger in a gold sheath — presumably not a common accessory back then — that was given to Amenhotep III, Tutankhamun’s grandfather, by the king of Mitanni, a region of Anatolia, when the pharaoh married his daughter.
So perhaps Tutankhamun’s space dagger was a family heirloom, received from abroad. The researcher’s elemental analysis also indicated that gemstones in the dagger’s hilt were attached with lime plaster, which was commonly used in Mitanni but did not catch on in Egypt until later.
Arai said that future studies will be helpful to further confirm this assessment of the blade. Whether an epic wedding present or not, this dagger’s story did not end with its royal burial.
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