SEM images of the endmembers used in this work (shown from the top). Panels A and B: Synthetic amorphous carbon. Panels C to F: Images of different grain size samples of pyroxene augite and plagioclase bytownite. In detail: augite with grain sizes < 50 µm, 50-200 µm, 200-500 µm, 500-1000 µm is shown from top to bottom in panels C to F; bytwonite samples with grain sizes < 50 µm, 50-200 µm, 200-500 µm, and 500-1000 µm for are shown from top to bottom in panels G to J.