# After one year exploring Jezero's crater floor, has there been any investigation into the presence of trace elements with PIXL?

PIXL instrument chart sample Credit:NASA/JPL-CALTECH

Of course PIXL has been used already in Jezero crater, but as far as I know only to identify mineral compositions and textures, as described in this Lunar and Planetary Science Conference paper.
The article How vanadium could be a beacon for Martian life shows that knowledge about the presence and/or quantity of some trace elements could be important.
According to the page for scientists PIXL could even detect important trace elements such as Rb, Sr, Y and Zr at 10's ppm level.

• I don't get your question. As you say PIXL has been used to identify mineral compositions, and trace elements are part of the composition. What are you saying hasn't been done?
– GdD
May 16 at 14:03
• You can start your own investigation right now, all the data is readily available! pds-geosciences.wustl.edu/missions/mars2020/pixl.htm May 16 at 16:56
• It's a bit too much work for me right now. I suggest checking the documentation "RDR SIS" for the "RPM" data format. That's basically a table for 22 elements for each scanned pixel, including Cr and Ti. First plots can easily be made with any spreadsheet software. The main issue is that the measurement time is too short to see trace elements properly, so you need to average over a large part of each image. May 16 at 19:50
• Quite possibly because identifying minerals gives a bigger picture of the geology of a region. Trace elements are minor elements that may add intrigue.
– Fred
May 16 at 20:07
• @OscarLanzi This is not rock, but NIST 612 reference material. Magnesium shows up just right of Sodium - but at a 30x smaller peak, so it vanishes in the gap between Sodium and the unlabeled Aluminum peak. May 23 at 9:32

Thanks to @asdfex for his link to PIXL data in the PDS Geosciences Node.
There's a link to the Mars 2020 Analyst's Notebook tool with the PIXL instrument's data archive.
In the archive I found two MSA files each containing so-called histogram bulk summed spectra. (page 40 for explanation)

Each of the 4096 channels of the PIXL instrument that counts the re-emitted X-rays from a target, has its own unique 8 eV range and they fit together to cover the total 32.768 keV energy range.

The MSA files contain a header followed by 4096 rows, each with 2 values, one for each detector, representing bulk sum intensity at each channel.

So I looked for all the maximum and minimum values in the rows and with the help of the histogram representation in figure 14 and this energy table for EDS analysis I could find the max. X-ray counts for the different elements.

               Sol 140  (275 min.)                Sol 167 (468 min.)

Element     Top      Left      Right           Top      Left      Right

Na        5361        -        524          11202        -       3289
Mg       25328     20492     11723          20302     12390      5925
Al      114989    101384     57502         161257    146880     74567
Si     1020232    962744    982363        1682175   1595484   1602593
P        45481      7612     28329         105844     26262     77713
S       383118    365966    329125         297494    269363    229758
Cl      286871    232879    277149         792033    724297    772907
K        67628     57905     52775         117093     97968     88794
Ca      580670    565817    548754        1356676   1328377   1279895
Ca       91180     59264     78017         209764    132983    188783
Ti       90868     77706     71454         293708    272727    257282
V        29756     10342     10416          72306     35880     45220
Cr       38408     19068     20287          37335     10250      9939
Mn       90854     72733     59558         164931    137535    116169
Fe     2940961   2909664   2916046        5212902   5164162   5168024
Fe      441308    416393    428950         777404    732526    759197
Ni       15684      3326      4956            -         -         -
Cu       14117      3390      2744          21443      4105      4379
Zn       14562      3189        -           19656      2568        -


Notes:

• Every value in the table is the mean of the 2 detector values.
• A value in a "Left" column is the difference between the "Top" value and the next minimum value to the left of the "Top" value in a from the table produced histogram.
• A value in a "Right" column is the difference between the "Top" value and the next minimum value to the right of the "Top" value in a from the table produced histogram.
• Ca and Fe have 2 max. values next to each other.
(See the histogram representation in fig.14)
• Could you add a link to the source of this table? May 31 at 17:34
• I guess you used ps__0140_0679334390_000rbs__00518120532812811688___j02.msa . So I made: i.stack.imgur.com/ZrPrE.png (to be refined ...) May 31 at 18:18
• @asdfex Yes indeed, that's a great histogram, much more user friendly. The other one was (if you didn't guess already) ps_0167_0681742997_00rbs_...., I think they are the only rbs files so far. Very suitable for an "extra" answer ! May 31 at 19:07