The study of induration and lithification of sediments on Mars seems to me to be in a state of flux. We have many on-the-ground observations, currently from Curiosity as she scales Mt Sharp in Gale crater. And if course the current work of Perseverance in Jezero.
My general take is that without deep burial, compaction is going to be mild, and induration will be limited to low-temperature hydrothermal processes involving sulfates.
This should prove to be an interesting trek.

--Bill

Actually, this kinda-sorta reminds me of the layering you see in 'pegmatite' in the Atlantic rift basin.

Basically, in the same way that a drying sea, deposits different layers of less and less soluble salts, but because as magma cools, you get a similar effect because magma and that doesn't flash freeze into glass, has time to let mineral crystals "snow out" as the flow cools.
The very bottom of the magma chamber has crystals of the first minerals to freeze, while the top of the magma chamber concentrates those minerals and elements that are the last to freeze- which is why diabase or dolerite anticlines are associated with gold, copper, silver deposits

Basically, "applejack" the same way that people have made hard cider, and then freeze out the water into slush, and keep the fractionated / enriched liquid as a liquor.

What looks like light green colour coatings?

ADMIN: 9 posts moved to new topic for discussion of image hosting/size/etc.

The reason I suggested floodplain was the resemblance of Ingenuity images to ridge / swale configurations.

This SuperCam shot (Sol 206) makes me feel quite confused about the origin of this rock. It seems like a layer that has been altered from botton to top (attending to the higher degree of cementation in the lower part and the more massive appearance of the top). Even there are some translucent grains.

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Sol 205 SuperCam Remote Micro Imager with sol 205 Mastcam-Z context and sol 206 Navcam context.
Judging from the Navcam image, the SuperCam looked at a rock slab from the same layer that was abraded next day/sol.
Two sol 205 Mastcam-Z images (the overexposed ones) taken at the same time allow the distance and size of the SuperCam image to be calculated.
If there is no systematic error in my calculations, the imaged circle has a diameter of about 44 mm and is about 2.4 m away from the Mastcam-Z.
The average diameter of the grains (crystals?) is about 1.4 mm, corresponding to very coarse sand.
However, the grains are angular and not rounded, and I cannot see any cement, matrix, or pores between the grains.
The brighter material on some upper grain boundaries is external dust.
Although it most likely belongs to the same layer, the interior of the abraded rock on sol 206 looks quite different.

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An interesting rock, indeed.
Here is my processing of the same SuperCam RMI raw image with slightly enhanced colors, sol 205 Mastcam-Z context and sol 206 Navcam context.
As for the cement: maybe that's not cement, but the start of weathering at the grain boundaries and/or very fine dust?
The translucent grains seem to have a more olive cast compared to the opaque grains.

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Looking at these Super Cam images, I keep returning to a fractionated basalt. On the wind-abraded fracture surface I see olivine as the green-tinted transparent clasts and pyroxenes as the blue-tinted clasts (or phenocrysts) near the top. This could be considered an ambiguous specimen in need of coring.
Here is a terrestrial example of a differentiated igneous rock:

For my part these images reflect somewhat poorly sorted clastic rock encompassing the range of angular and spherical shapes. The potential cement does not match the colour of the dust coating the upper surface of the rock and protruding parts of the fractured surface. The Jezero catchment is mafic and olivine rich so olivine particles could be anticipated in immature sedimentary rock.

I'm a mess.
I vacillate between these two views.

--Bill

The texture seems to be about that of 20-grit sandpaper.
The crystals are very interesting!
They seem to be the softness of salt as they easily grind into a white powder.

Haha I feel the same way. Just about every week I flip flop between 'basalt' or 'sandstone'. That supercam image though... to me that really looks like the angular grains of a well sorted sandstone, which has a basaltic mineralogy (unsurpising given this is Mars we're talking about), though I understand how others see crystals where I see grains. I know scientists will be very eager to get their hands on this core. The layering and rock textures here are fascinating - perhaps the most interesting site Perseverance has reached yet

Don't forget the possibility that the rocks originated as ash deposits rather than lava flows. Ash onto land, ash onto water, lava flows, basaltic material redistributed by fluvial action - there are lots of options, all with potentially similar compositions.

Phil

And pyroclastics are another possibility.

--Bill

The Rock it's self has a dark dark gray blue thin veneer as do just some of the crystals inside, and some of the crystals (drill area) look to have an iron coating which would be more then likely a iron stain.
This rock seems to have dust adhering to it where there are other rock along the way that are blue color that are dust free and very very shiny.

As for the "blue rocks": in reality they are rather gray. If there are blue rocks in my processed images, the blue is due to image processing designed to enhance the hue differences in the raw images,
and in some cases (especially the SuperCam RMI images) simply because I don't have a calibration for white balance and therefore use other SuperCam RMI images for flatfield and white balance.

Below is an example of a Mascam Z image of sol 145 with a part of the original image on the left. One method of increasing hue differences is to increase saturation.
The result is the displeasing image in the center with greatly exaggerated yellow-orange. To avoid this strong color cast, all RGB values can first be shifted
from yellow-orange toward the gray axis in the color space. Original RGB values that were gray or at least less saturated inevitably move into the blue range
and become even bluer by increasing the saturation. This is the reason for the "false-color blue" rocks in the right processed image.
My methods are more complicated, but the priciple is similar to the one described above.

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Years ago we started to enhance color differences while minimizing the "Orange Overcast" present in the images from Opportunity and Spirit. This was done as Geologists to spot gross compositional differences in subtle color differences. Your processing technique shows close to the same thing we did.
This blue suggests a basaltic composition.

--Bill

Here comes some more false-color blue. In reality it might be a gray, probably with a subtle green tint.

Abraded rock on sol 207.
1) Sherloc Watson camera raw image, enhanced with principal components analysis.
2) Merged overlay of Sherloc Autofocus and Context Imager raw image (brightness and detail) and no. 1 (hue and saturation).
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I like this "merged overlay" processing; it shows the glint (luster) of the abraded (fractured) mineral grains very well after the "dust blower" cleans up after abrasion.
This is a very informative view: it suggests a look at the mineralogy of this specimen, and further suggests that it appears to be well-indurated (cemented) and even suggests some weathering between the grains. It would be interesting to learn the drilling pressure on the core sample.
Indeed, there is a lot going on in this image! Thanks for sharing it, Tau.

--Bill

Are you talking about Tau's enhanced versions of Ingenuities images? Basalt is generally grey to black in colour but some crushed basalt has a blue black appearance which gave rise to the term blue metal as road base. But perhaps a visual example is the best way to explain it to you. In Tau's copied image below the false colour image is merged with the mastcam 'real colour' image. As you can see the rock is not blue and the false colour image could best be described as dark grey. The same is true of Ingenuities images. The enhanced, false colour images are not 'real'.

The outcrops in that image look grey to me but I do note the horizon at the top right shows a grey blue sky. Ingenuity color camera images vary between near grey scale and full color and I assume this is a function of the Bayer color filter array. The outcrops are not blue. With respect to the SHERLOCK context image the acronym, stands for Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals. The images are taken under ultra violet illumination.

The color balance of this COTS camera has been quite unpredictable if you go back and look at all of the images. Having said that, are these rocks "bluish" by some metric, sure, wouldn't surprise me.

As for the shiny rock, I've taken images of regular old quartz-bearing rocks in the lab with MAHLI that looked just like this image, you don't have to resort to an unlikely hypothesis involving water to explain it.

And one item added to the toolkit on the Arm is the GDRT (dust removal tool) which seems to do an exemplary job of removing the residual dust from the abrasion process. I don't have a feel for how this camera shows the various degrees of luster, but I believe that I'm seeing a vitreous luster.

Based on SuperCAM RMI pictures - they have.

Thanks djellison for posting that link, I hadn't come across that page yet and love the Enhanced/Natural color toggle button below the images
https://mastcamz.asu.edu/mars-images/images...al-color-images

I've been flummoxed by the radial pattern, as as can be seen in this example reference earlier by Tau. I was losing too many synapses wrestling with the impossibility of radial abrasion, so perhaps the pattern is simply composed of remnant dust left over from the GDRT process?
I haven't kept up with this mission as well as i'd like so this tool is new to me and of course am firstly concerned about how many uses the nitrogen tank can supply.

I believe this is the link but it's paywalled

Drive on Sol 210 (site: 7, drive 2050)
L-Navcam mosaic of 4 frames roughly tiled in MS-ICE (de-greened)
Click to view attachment

The Ingenuity color camera is an off-the-shelf Sony IMX214 camera module, which can be googled.

--Bill

When you find something about how the auto white balance works under martian conditions, please send a link.

Egads, "color balance" is a can of worms. It means precisely what you want it to look like. And auto white balance comes from an algorithm analyzing the RGB content of the scene and correcting it to whatever the developer thinks. As do the scene modes: sunlight, overcast, afternoon, tungsten or fluorescent. JPL may have even set their own custom balance using a Martian McBeth Card.
Let me make a discrete exit by dropping a Sony link:
https://helpguide.sony.net/gbmig/45349331/v...0000522853.html

ADMIN: Due to unacceptable, argumentative conduct by a member 14 posts--including knowledgeable and well-intended replies intended to correct several incorrect perceptions and assumptions by said member--hidden. Possibly more to follow.

EDIT: Removed 7 more posts in an attempt to make the discussion more linear. If I accidentally deleted anyone's post that they feel should be restored and preserved in context, please PM me.

Apologies for the entire debacle, which unfortunately lasted far too long. Even evil robots gotta work a day job.

The abrasion bit is driven by a rotary-percussibe drill, and the abrasion bit has an "unusual tooth pattern: three parallel lines of different lengths, arranged asymmetrically. When the drill spins and hammers with an abrading bit, that tooth pattern creates crisscrossing, well distributed impactsin the rock".

I haven't been able to find any specifics about the exact camera module being used, especially about the optics or the auto white balance settings/behavior. I'm fairly sure that however it's being operated, it wasn't custom-set for the expected martian lighting conditions. We saw a lot of weird white balance issues with the EDLcams also. I don't know how the RDR products are being produced for any of these cameras and I would take their color rendition with a grain of salt.

Absolutely. Ingenuity is a technology demonstration and I don't expect a miraculous color camera setup. And there have been weight, size and other constraints with this camera, so all things considered it has worked brilliantly.

--Bill

It's been discussed on here many years ago, but "true color" is somewhere between hard to come by and absolutely nonexistent. The spectrum of martian daylight is certainly variable depending upon latitude, altitude of the Sun, and multiple parameters of atmospheric dust over a given time and place. A three-color camera (or our eyes) loses information regarding the fine details of any given spectral curves, and creates ambiguity between, to pick one example, narrowband yellow on the one hand vs. the sum of narrowband green and narrowband red on the other. The number of nonlinear interactions is boundless and that's even before the important matter that mcaplinger mentions of white balance in an off-the-shelf system.

VIMS on Cassini is an example of a multispectral imager that was designed to return data that could be used – in ideal cases – to constrain the composition of the surfaces that it imaged. That isn't the objective or design of every camera, nor should it be.

The post-drive Right-eye Navcam pan from Sol-210.



Polar

Very nice, James. Here is a version in my circular projection - more compressed towards the middle, stretched radially at the horizon.

Phil

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The question "What colors would we perceive if we were standing on Mars?" may not be answered until we are actually standing on Mars, because our visual system (eyes and brain) and digital cameras work differently.
For example, we cannot turn off our automatic white balance, which can be very confusing at times. An impressive example are the "gray strawberries". The effect is explained thoroughly with visual examples in this video (13 min).
Taking into account the gray-strawberry-effect, I would expect to perceive a less saturated and lighter red ochre / sanguine/ red chalk tone than in the calibrated natural color images, and would not exclude an apparently slightly bluish tint in our perception of some gray rocks.

To risk extending this OT discussion too far, that same auto-white-balance effect should also occur if you can view an image of Mars on a large enough display. A properly calibrated image in sRGB colour space, viewed on a well-calibrated sRGB monitor, should reproduce well the 3-stimulus you would have on Mars. It's the ambiguity that JRehling mentions that allows that to work (ie, you don't need to reproduce the full spectrum).

In fact, the issue of "color balance" subjective and a matter of perception. And add to that the eyes will adapt to the color temperature of the light they are in. Sitting in your library, you don't see the warm tones of the tungsten lighting. Moving into your kitchen, you don't notice the bluish tinge of the LED lamps. Or stepping outside, the 5000*K of the natural sunlight. The eyes adapt.
Literally, color balance is what you want it to be.

Not to give the mods too much of a workout, but this whole color discussion should be moved elsewhere.

Agreed. I thought that the "true color" had already taken place somewhere, but I couldn't find it, or I would simply have linked to that.

Some partially overlapping photos taken by Mastcam-Z on sol 207 at the same second allow a stereometric grain size analysis.
Most of the grains in this image are about 1.8 mm in diameter, which corresponds to a very coarse sand.
To get a real sense of the grain size, zoom in or out until the white bar is exactly 10 mm long on the display.
Between the grains is much finer material (dust?) that is too fine to be measured with stereometry.
To prove the calculation, I determined the diameter of the abraded depression in other sol 207 images,
and the result is 49 mm (4.9 cm), which agrees well with the 5 cm diameter of the abrading bit given by NASA.

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Tau, the typically assumed size of terrestrial volcanic ash is 1.5 to 2mm. We don't know any if the variables involved with the Martian ash size distribution, but your measurement does agree with the terrestrial size. We don't know with certainty about the composition of this soil.

--Bill

2 mm is around the maximum size of volcanic ash particles but the vast majority are much smaller. It is almost certain that there will be some volcanic ash present in Jezero sedimentary rocks but the majority would be in the matrix. To give an example of size the image below is volcanic ash from the Mt St Helens eruption. The width of the view is 4mm.

How do we guess the size of ash particles on Mars?
I know they calculated that raindrops could be about 1/8th larger on Mars-
https://www.sciencedirect.com/science/artic...6005?via%3Dihub

Looking up and down core hole #2 on sol 198, from three, cross-faded Watson images:

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click to play (wait a bit).

And an animation of another Watson series of focus down the core hole, of 16 images:

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Core hole #3 so 198 Watson animation 1:

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