I know little about mass spectroscopy. However, years ago, people who know a lot told me that EDX does not work reliably with samples of material such as powder or other particles not compact or electrically conductive. Here is an on-line discussion that confirms this:
I learned this when I saw results from an EDX analysis of powder that seemed to be off the wall and useless. That was my impression, and that is what the mass-spec people confirmed.
The photos from Me356 appear to show fractal material that seems to be loose or not even attached to the substrate, so the results may be questionable. I cannot judge, but I think another method would have to be used to confirm the analysis.
Me356 is using a scanning electron microscope (SEM) to look at his fuel
Apparently it is an SEM with an EDX built in.