Figure 4

Quantitative element ratio plots across the space-weathered rim of a pyrrhotite grain. Quantitative element ratio plots across the space-weathered rim of a pyrrhotite grain exposed on the surface of particle RA-QD02-0125, which show a zone of sulfur depletion and iron enrichment in the outermost approximately 10 nm of the grain. Element ratio profiles were extracted from the spectrum images.