Adoption of a robust X-ray fluorescence spectroscopy quantification and spectrum fitting routine calls for careful consideration on the inner workings and databases incorporated in its architecture. For analysis of micro-XRF data returned from the Planetary Instrument for X-ray Lithochemistry (PIXL), integrated on the Mars 2020 Perseverance rover, the University of Washington and the National Aeronautics and Space Administration (NASA) have invested in the production of an in-house micro-XRF software package, PIQUANT, capable of supporting quantitative elemental analysis of whole rock and geological materials. The PIQUANT software uses an iterative fundamental parameters physics-based model to convert X-ray peak intensity into elemental concentration, and has minimal reliance on calibration using standards. It also incorporates polycapillary optic transmission correction to account for photon passage in the X-ray optic of micro-XRF systems. This work introduces the key features of PIQUANT's architecture, its databases, models, assumptions and summarizes features available as part of the analysis products it generates. A working example of a quantification process available with this software is presented within.

The geological units on the floor of Jezero crater, Mars, are part of a wider regional stratigraphy of olivine-rich rocks, which extends well beyond the crater. We investigate the petrology of olivine and carbonate-bearing rocks of the Séítah formation in the floor of Jezero. Using multispectral images and x-ray fluorescence data, acquired by the Perseverance rover, we performed a petrographic analysis of the Bastide and Brac outcrops within this unit. We find that these outcrops are composed of igneous rock, moderately altered by aqueous fluid. The igneous rocks are mainly made of coarse-grained olivine, similar to some Martian meteorites. We interpret them as an olivine cumulate, formed by settling and enrichment of olivine through multi-stage cooling of a thick magma body.