Exsolution in Iron Meteorites. Bands of kamacite (Fe-Ni metal low in Ni) formed by exsolution in taenite, Fe-Ni higher in Ni. The two phases have different crystal structures. Kamacite exsolved along octahedral planes in taenite. IVA Iron Meteorite, Gibeon.
IVA Iron Meteorite, Gibeon
Photo by Jeffrey Gillis-Davis, U. of Hawaii
Iron-Nickel Phase Diagram
Growth of Kamacite
Matching the measured profile with calculated profiles indicates that the cooling rate of this sample is 1000 K/My.
In total, iron meteorite cooling rates range from about 1 to almost 10,000 K/My