Ah yes, I saw that in pre-print. For a moment I thought this was the paper about the clay-rich/high-aluminum white rocks down in the crater, but yeah, this is some fundamental work by Kathir et al., with very nice figures to boot. This quote has me laughing right now:

The Noachian basement unit of the Jezero watershed unit is enriched in Fe/Mg-smectites, but we have found no float rocks with these compositions. This suggests that Fe/Mg-smectite-rich outcrops are friable, poorly lithified, and not well-cemented, and thus less resistant to erosion.

LOL You don’t say… now where have I seen rocks like that recently? 😆