The surface of Rochette seems intetesting. Hopefully they'll core a sample to include that crust, instead of doing it from the "RATted" surface.

--Bill

What was said earlier was that at each sampling site they will do a detailed pre-sampling analysis and then collect the sample nearby.

Phil

Sol 184 LMastcam-Z:

Another LMastcam-Z view on sol 184:

Sol 187 Mastcam-Z left eye images of "Rochette"
A) Raw image with filter 0 (RGB)
B) Multispectral filters 0 to 6 principal components transformed to false color RGB
Colors in the legend are averaged from the image
1) Rock ventifact surface in direct sunlight. The color differs from the abraded interior.
2) Crust (desert varnish?) or hard coating on ventifact surface, partially eroded or spalled
3) Dust accumulation
4) Abrasion powder

A
B

Any way to look for manganese or zinc?

What would Manganese or Zinc compounds suggest?

I'm wondering if this dark zone might not be contact metamorphism from the contact of the underlying clastic unit with molten Basalt.
This will be an interesting specimen.

--Bill

Manganese and zink are excellent polymerization/cracking catalysts and so are very interesting for a-biotic or pre-biotic organic chemistry. Industrial "cracking catalysts" use manganese silicates and zink ferrites are to break (or make) long chain hydrocarbons.

Similar grains might help turn atmospheric methane into sticky paint like goop that sticks to rocks and makes "desert varnish".
Interestingly, THAT sticky goop traps MORE minerals in dust and you get more potential catalytic compounds. Think of the catalytic converter in a car, it makes it much easier to convert hot long chain hydrocarbons into CO2 and H2O. That works in reverse, so a catalytic layer of "desert varnish" would change the energy budget for creating Martian methane or organic chemicals.

So, if you wanted a sample of EVERY mineral in the central & eastern USA, but could only take 1 sample, where would you go? The answer is- the Mississippi delta- because the delta sequesters microscopic mineral grains from every different type of Earth rock in the Mississippi watershed, carried their by water currents. But, that ALSO means you have tens of thousands of mineral grain catalysts close to each other, and subject to flow from fresh water rivers and tides.
So, the Mississippi delta, and Jezro delta, are perfect places to study the catalytic properties of microscopic mineral grains.

https://www.sciencedirect.com/science/artic...167268195000496

I fall in behind Andreas' " a wind polished, striated, very thin weathering crust". "Rochette" appears to be the product of erosion under current environmental conditions and given the basaltic provenance my stab in the dark would be primarily Fe oxide/hydroxide. Supercam should be able to determine the composition and we will be enlightened at what is going to be a extremely interesting LPSC 2022.

The Mississippi River watershed and delta is likely an overreach in comparison to the Jezero watershed. The Mississippi is huge in comparison and the time of travel of the suspended and bedload sediment can be measured in weeks and years. The sediments are quite weathered by the time they reach the Mississippi Delta. I don't recall it's area and I've not measured it, but I've the impression that the Jezero watershed is not that large. The later surface was the Syrtis volcanic province, which means basalts and basaltic clays and weathering products. I don't recall.what the pre-volcanic terrain was like, but I'd suspect more basalts and basaltic clays and weathering products.
It will be instructive to get.a better idea of the chemistry of the near-ubiquitous films and varnishes of Mars.

--Bill

Core in the sample tube (Sol 190)
I've roughly brightened the inside of the sample tube

Rocky sample inside!

Good show. I see core in the core tube.

It looks as though they conservatively didn't include the varnish/ weathered top of that section.
ADDED: no, wait. The actual coring location was above the initial RATted cut; you can faintly see it below the core hole under the cuttings.

--Bill

Detailed press release LINK
I have annotated 2 of the photojournal images (for those not familiar with the coring bit etc)