Fig. 3: High-angle annular dark-field–scanning transmission electron microscopy image and corresponding elemental mapping of the space-weathered framboid in FIBii.

This thin section corresponds to that in Fig. 1D. The original surface is at the left-hand side of the image. Note that 30-nm-thick carbon layers were deposited onto both faces of the thin section. Oxygen in the rounded particles at the surface and sodium, magnesium, silicon, and sulfur in the matrix just beneath the rounded particle have been depleted. Tiny aluminum round spots below the surface suggest melting at a high temperature. The yellow lines are guides, indicating the surface and positions 1 μm and 2 μm below the surface. The white brackets in the iron map indicate areas where iron appears to have diffused from the spherical particles into the surrounding matrix. The scale bar is 2 μm.