Fig. 1: Overview of the studied spherical iron-sulfide grains.
a–d Transmission electron microscopy bright-field images of two spherical iron-sulfide grains and their corresponding quantitative energy-dispersive element maps, showing a ring of equally spaced pure-iron tentacles at the grain edges and a wide distribution of iron-oxide (Mag) and pure-iron (Fe0) inclusions within the troilite (Tro) and pyrrhotite (Po) matrix. e–f Selected-area electron diffraction patterns of the matrix within an iron-sulfide grain and the iron tentacles around the grain edge, showing intergrowth of troilite and pyrrhotite in the matrix and metallic iron (α-Fe) protruding from the iron-sulfide grain. The diffraction area is indicated by the dashed region in (a). g Morphological features at the edges of the studied iron-sulfide grain. h Smaller vesicles (Ves) scattered within the grain.
