On the occurrences and formation mechanisms of cliftonites: The case of Campo del Cielo iron meteorite

The Vaca Muerta mesosiderite: The path under which Fe‐Ni alloy ±C phases could have formed

“…This indicates that the nanostructured taenite particles were formed by the tie lines in a rather large two‐phase region (γ + L) with a varied liquid composition in the Fe‐Ni‐C system at temperatures above the eutectic point, for example, at 1500 K (the reader might check the Supplementary Material). Such taenite crystallites may act as nucleation agents for the formation of graphite given the multiphase nucleus with Fe and Ni elements to chemically catalyze the growth of graphite (García et al., 2023; Laffont et al., 2020). The liquid environment facilitates not only epitaxial coalescence of taenite crystallites but also parallel epitaxial assembly of carbon monolayer (i.e., graphene) and lamellae into TG ribbon, analogous to the fabrication of macroscopic fibers and ribbons of oriented carbon nanotube (Vigolo et al., 2000).…”

“…By contrast that with larger size would have shrinkage or shock‐induced microcracks for infiltrating such a partial melt and partially crystallized as graphitic vein with taenite aggregates (Figure 3b) following the carbon transformation sequence: flexible rolling lamellar basal‐plane graphite → rigid TG nanoplate or ribbons with crystalline domains → shocked to form a high density of defects (Figure 3d,e). In the final transient of a solute pileup at shrinkage fissures, the cooling rate was high enough to suppress coarsening but allowed coalescence of the nanosized taenite to form aggregates and enhanced turbostratic faulting (shifting)/bending/folding of the graphite ribbons typical to a process in a liquid environment (García et al., 2023).…”