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Swollen Kamacite lamellae |
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| Yarovoye, IIIAB Iron, fine octahedrite . |
| Lamellae in iron
meteorites are classified as secondary structures, forming in space during the
gradual cooling that follows the primary crystallization of an asteroid's
molten iron-nickel core. This process unfolds over millions of years, allowing
the iron-nickel alloys-kamacite and taenite-to undergo exsolution, resulting in
the characteristic Widmanstätten pattern. The term "swollen kamacite lamellae" refers to thicker, more prominent kamacite bands that exhibit a more irregular shape than typical lamellae. This "swollen" appearance can arise from variations in cooling rates or elevated concentrations of elements such as phosphorus, sulfur, and carbon. These elements influence the diffusion rates of nickel and iron, which in turn affect the size and shape of the primary kamacite lamellae. Subsequent impact events can further modify these structures through shock metamorphism, often leading to recrystallization of the metal and altering the original lamellae. |
Figure 1. Scale bar 1 mm. |
| Yarovoye, IIIAB Iron, fine octahedrite. |
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