piece of material from Mars

The above is a magnified part of the original image below captured by the Curiosity rover on Mars on sol 1729 (June 17, 2017).
From the added information with that raw image it can be estimated that the distance between the lens and the target was about 14 cm.

original image

Below another image of the thin piece with surroundings in the sunshine.
Click (or double click) on the image for magnification.

piece with surroundings

Asking about the chemical composition of this piece of material on space exploration SE, it appeared from the answers that most likely it is CaSO$_4$, perhaps the hydrated form gypsum.
I've seen many other raw images from Mars, but not anything like this.

What could this thin piece of material be, does it resemble anything on Earth ?

  • 4
    $\begingroup$ @ebv: this isn't like the typical rock ID questions we get, where someone has a rock, taken a usually out of focus photo & asked, "what is it?", because the rock to them looked either weird of "pretty". Such questions lead nowhere & are of no value to this site. This question is about NASA photos of geological/mineralogical features on Mars & it has merit. It's not a rock in isolation with no context, but a rock or mineral in-situ. I'm voting to keep this question open. $\endgroup$
    – Fred
    Commented Jan 15, 2020 at 19:32
  • 1
    $\begingroup$ @Cornelisinspace the "plastic" surface is a pruduct of the very fine grain, i think. It does not lie loose on the surface but could have been built up e.g. by pore water like the other bumps, along cracks and such. Keep in mind that erosion on Mars is slow, it may be 100s of millions of years old, maybe more and up 4.5 billion years, slowly been built up by evaporation. Other than on earth, these sediment processes have time there. But this is not a better guess as any other. $\endgroup$
    – user18607
    Commented Jan 15, 2020 at 19:59
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    $\begingroup$ @ebv The consensus appears to be that We should retain questions that are interesting for some other reason than "identify this rock", which would certainly include this question. Therefore I think this question should be welcome to remain. $\endgroup$
    – gerrit
    Commented Jan 16, 2020 at 8:54
  • 1
    $\begingroup$ @Conelisinspace It's a bit much to cover all possible user interfaces in parenthesis. Click, click twice, tap, push... $\endgroup$
    – gerrit
    Commented Jan 16, 2020 at 9:43
  • 1
    $\begingroup$ Put that into your question please. $\endgroup$
    – Jan Doggen
    Commented Jan 17, 2020 at 16:26

2 Answers 2


What you can see in the bottom picture is sandstone/mudstone/claystone.

If you look at the bottom picture top right you can see a thin rock that has split off, this is how a rock splits after it has been heated and then suddenly gets cooled down as it does on Mars when the Sun goes down.

On Earth the change in temperature is too slow for this to happen in nature, but you can see this if a fire has been burning on top of a rock/stone and it has been rapidly cooled down.

This is how mining was done before explosives where invented, heating up the rock until it is "glowing" hot and then throwing water on the rock to suddenly cool it down so it fractures.

  • $\begingroup$ According to the answers on space exploration SE the surrounding is mudstone. $\endgroup$
    – Cornelis
    Commented Jan 15, 2020 at 17:58
  • $\begingroup$ so the particle size is smaller but the same material edited answer. $\endgroup$ Commented Jan 15, 2020 at 18:00
  • $\begingroup$ I've read about intercalation of CaSO4 veins with mudstone layers, so the white stuff could be the CaSO4. $\endgroup$
    – Cornelis
    Commented Jan 15, 2020 at 18:07
  • $\begingroup$ rock id is off topic here so i focused on the mecanism that created the thin rocks,you will find the same types of material on mars as you will on earth. $\endgroup$ Commented Jan 15, 2020 at 18:14
  • $\begingroup$ But I asked specifically about that thin piece of material on the mudstone. $\endgroup$
    – Cornelis
    Commented Jan 15, 2020 at 18:24

If you enlarge the picture and follow a line at 1 o'clock from the weirdly shaped piece in question, a few feet away from it at the back of an imaginary 'man's head' rock, you will see a similar convoluted piece. Now follow a line at 10 o'clock from our original specimen, and also a few feet away is a longer,straighter piece in the process of eroding from the rock. Nearby are more pieces eroding.

It seems to me that there were cracks or voids in the sandstone/mudstone into which a harder intrusion has been introduced. As the rock erodes, which is more slowly on Mars than on Earth because of the lack of wind and rain, these intrusions are eroding out and sometimes end up lying on the surface. As to the nature of the harder rock which forms the intrusions, I couldn't say. Perhaps someone else will have an idea. Is there anything like it on Earth? Probably, because most things on Mars have their counterparts on Earth, but I couldn't tell you where to look for these strangely shaped rocks.

  • $\begingroup$ Credible explanation ! You used the term "convoluted" and indeed it looks folded and deformed, but after eroding. Still you name the piece, "rock". Are there rock materials that can be bended or deformed without crumbling ? $\endgroup$
    – Cornelis
    Commented Jan 18, 2020 at 14:46
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    $\begingroup$ Not after they have formed and hardened. Some are deposited by mineral-bearing water, and minerals are precipitated in cavities. In other cases there are molten intrusions which are volcanically forced into cavities or even create cavities, where they harden. The exception to this is where the strata are deep and under great heat and pressure. In such cases, the pressure of plate movements can cause folding and deformity in the course of many millions of years. Such bending of solid rock without crumbling involves huge layers of strata, not tiny pieces of rock. $\endgroup$ Commented Jan 18, 2020 at 16:21

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