Extended Data Fig. 6. High-resolution images of sulfide and metal in a frothy layer on the large grain A0058–C2001.

(a) A BF-TEM image of a spherical Fe-Ni sulfide bead in the frothy layer in the cross-section sample A0058-C2001–03. (b, c) Enlarged BF-TEM images of the red and green boxed areas are shown in (b) and (c), respectively. The lattice fringes shown in (b) are 0.30 nm, which suggests $\left(20\overline{2}\right)$ of pyrrhotite (Po). The fringes shown in (c) are 0.18 nm, suggestive of (4 4 0) of pentlandite (Pn). (d) HAADF-STEM image of the cross-section sample A0058–C2001–07 shows a chain of nanophase (np) (Fe, Ni)S in the thin (~100 nm) smooth layer. (e-h) An aggregate composed of nanophases (<100 nm) on the frothy layer of the cross-section sample A0058–C2001–7. HAADF-STEM image of the aggregate is shown in (e). Enlarged BF-TEM images of the red and green boxed areas in (e) are shown in (f) and (g), respectively. The lattice fringes shown in (b) are 0.30 nm, which suggests $\left(20\overline{2}\right)$ of pyrrhotite (Po). The fringes shown in (f) is 0.20 nm, suggestive of (1 1 0) of kamacite (Fe°) and those in (g) are 0.22 and 0.30 nm, suggestive of $\left(1\overline{2}4\right)$, and (1 1 0) of troilite (Tr). (h) EELS map of the same area shown in (e) shows that the aggregate lacks oxygen and contains iron.

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