Kamacite
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Kamacite is an alloy of iron and nickel, which is found on Earth only in meteorites. According to the International Mineralogical Association it is considered a proper nickel-rich variety of the miner
Widmanstätten pattern showing the two forms of nickel-iron minerals, kamacite and taenite
Kamacite and taenite after taenite, exhibiting the octahedral structure of taenite, Nantan (Nandan) iron meteorite, Nandan County, Guangxi Zhuang Autonomous Region, China. Size: 4.8×3.0×2.8 cm. The Nantan irons, a witnessed fall in 1516, have a composition of 92.35% iron and 6.96% nickel.
Widmanstätten pattern
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A Widmanstätten pattern, also known as a Thomson structure, is a figure of long phases of nickel–iron, found in the octahedrite shapes of iron meteorite crystals and some pallasites.
Kamacite
…a major constituent of iron meteorites (octahedrite and hexahedrite types). In the octahedrites it is found in bands interleaving with taenite forming Widmanstätten patterns. In hexahedrites, fine parallel lines called Neumann lines are often seen, which are evidence for structural deformation of adjacent kamacite plates…
Segment of the Toluca meteorite, about 10 cm wide
Widmanstätten pattern in the Staunton meteorite, found near Staunton, Virginia in the mid-19th century. Six pieces of nickel-iron were located over a period of some decades, with a total weight of 270 lb.
The fine Widmanstätten pattern (lamellae width 0.3mm) of a Gibeon meteorite.
Etched slice of a Canyon Diablo meteorite showing a Widmanstätten pattern