Swiss Pumice Cheese

A Sol818 FHaz anaglyph

The Navcam view on Sol 817.

Jan van Driel

I think the image from my previous post is the HazCam view of what is vertically above the 'I' in Curiosity in Jans' pan above

Circular version of Jan's pan:



Phil

Focus-stacked Sol 819 MAHLI of a brushed surface.
The rock looks like a sandstone or a sandy mudstone with some whitish veins, and mostly angular grains.
Most grains look greyish, some grains look reddish-orangish. Here a version enhancing the most saturated patches:

Comparing saturation of the orangish spots hints towards an iron contents above the iron contents of the ubiquitious dust. The hue of the orangish spots seems to indicate high iron-III as hematite; goethite and limonite low, if any.

[edit] vesicular 'pumicey' slab anaglyph from sol819

Why do you call it a pumice?

My favorite interpretation candidates for the layering (Sol 819) thus far are annual (glacial?) varves (favorite), and cross-beddings (backup).
Thus far I didn't see clear evidence for cross-bedding.
(And no evidence at all for pyroclastic activity.)

I stand to be corrected but this looks more like planar (near horizontal) lamination formed in a low flow strength regime.

Target "Mescal" at Pahrump Hills / Alexander Hills with context images, sols 819 and 822:

The scale for the highest resolved MAHLI is calculated according to the formulas of this post from a motor count of 14762 taken from this image, since the motor count 14426 of the used focus stacked image refers to a subframe which has been out of focus.

If the rock can roughly be classified as an arkose (feldspar-rich sandstone with angular grains, usually poorly sorted), the outcrop may be located in the lower parts (middle or tail) of an alluvial fan, as far as notions from Earth are applicable.
Interesting enough, even the richness in hematite (redness) matches.

The size of the sand grains looks like about 1 mm. According to the Wentworth chart, and applying a factor of 0.6 due to the lower gravity, the settling velocity for angular grains should have been near 6 cm/s, threshold velocity for traction near 30 cm/s.

I'm going to reduce the probability for the varve interpretation of the lamination.

Great analysis Gerald. I thought these deposits were older than the alluvial fan. I guess it is possible and probably that there were multiple episodes of fan deposition, but given the distinct mineralogy difference, I would suspects a different deposition mechanism.

Translation with Google My opignon on the subject:

Event impacts and hydrothermal event loingtain seasoned and sudden collapse.

My Florida sand grain size is:
~.15mm (inland)

A comparison of two MAHLI images of the same target.

One from Sol34, the other from Sol825.





Without cheating! Which is which?