Platinum is an extremely rare metal, occurring at a concentration of 0.005 ppm in Earth's crust, but in some alluvial deposits it is often found chemically uncombined as native platinum and as an alloy with the other platinum-group metals.
Since Jezero's fan-delta deposit has an alluvial origin, isn't it likely then that it will contain platinum and other platinum-group metals at a higher concentration, high enough to be detected by Perseverance's PIXL or SHERLOC instruments ?

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    $\begingroup$ Where ‘often found’ is ‘I never have seen any walking around alluvial deposits’ mind you… $\endgroup$
    – Jon Custer
    Commented Jan 23, 2023 at 16:57
  • $\begingroup$ @JonCuster South American natives probably were the first who walked around and on alluvial deposits to find platinum and used if to produce artifacts. But good comment, I changed the first sentence somewhat. $\endgroup$
    – Cornelis
    Commented Jan 23, 2023 at 18:41

1 Answer 1


The question, Difference between "mafic floor" and "olivine-bearing floor" in Jezero crater? (Perseverance landing site), provides some insights.

The geology of the delta region of Jezero Crater is favorable for the presence of platinum because it contains mafic rocks. The source rocks for platinum are mafic and ultramafic igneous rocks. Platinum occurs,

Chiefly in placer deposits, or in mafic and ultramafic igneous rocks; rarely in hydrothermal quartz veins or contact metamorphic deposits.

Platinum usually occurs as disseminated grains in iron and magnesium-rich igneous rocks and in quartz veins associated with hematite, chlorite, and pyrolusite. When rocks weather, the heavy platinum accumulates as grains and nuggets in the resulting placer deposits.

There is potential for native platinum to occur in the Jezero Crater delta. That potential could be increased if the river that fed the delta passed through mafic or ultramafic rock along its path to the crater. The greater the exposure to such rocks, the greater the potential.

Whether the Perseverance Rover could detect native platinum would come down to luck. It would need to overturn the right rock and the nugget(s) of platinum would need to be noticeable. A large shiny nugget would be noticeable, microscopic gains would be more difficult to detect.

One the reason for my cautious conclusions is because, on Earth,

Platinum nuggets are actually MUCH rarer than placer gold nuggets are. Nearly all of the platinum found around the world is microscopic bits that are extracted from the ores, and not large enough to be captured by traditional placer mining methods.

In a very few areas, platinum actually forms in larger pieces, and when introduced to a stream or river, it will form a nugget just like gold will.

This is such an uncommon occurrence that only a handful of mining districts are actively being worked for platinum nugget deposits.

For purposes of comparison, the largest platinum nugget found is the Star or Russia, which weighs 14.55 troy ounces (452.556 g), whereas the largest gold nugget found weighed 2520 troy ounces (78.38 kg).

Having read the paper supplied in the comment, from Section 5.1.1, and elsewhere, the mottled terrain unit in the watershed appears to be basaltic and is thus mafic. If there is any platinum within the inflow delta of Jezero Crater it will most likely come from that unit.

Just because the geological conditions are potentially favorable for the presence of platinum nuggets or fragments it doesn't mean that such items will be present. The amount of platinum in the original source rock will be a factor. How it gets liberated will be another. The other will be the nature of the water flow through the erosion channels into the lake. This was briefly mentioned in the paper. A continuous water flow will aid the formation of nuggets and agglomeration of platinum fragments into large pieces because this provides more opportunity for platinum fragments to interact with one another. Seasonal inundation resulting from snow melt would provide a lot of water over a shorter duration, with the potential for more turbulent water flows and less time for prolonged interaction between platinum particles. If the water channels experience dry periods the platinum particles will be idle.

  • $\begingroup$ Despite your cautious conclusion your answer raised great expectations for me since Perseverance has such powerful instruments like PIXL, SHERLOC and for noticing from a distance, the SuperCam.! This article, agupubs.onlinelibrary.wiley.com/doi/10.1002/2014JE004782 concludes in section 5.1.1 that a unit within the watershed is the potential source for the Mg-rich carbonate and olivine mixture within the fan and floor deposits. If you're interested enough to read the extensive article I like to know your opinion if the potential for the occurence of native platinum is still present ! $\endgroup$
    – Cornelis
    Commented Jan 24, 2023 at 11:17

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