Hey Horton,That round rock does look c...

Hey Horton,

That round rock does look curious. The rock looks lighter in color than surrounding matterials (it may be the lighting).

If this is not an optical illusion what made it round like that?

Fluvial action can round rocks. Chemical deposition can form round concretions. Ice can form round objects. Meteorites can be roundish, volcanic bombs might be roundish.

It would be nice to see just how round it really is. Rocks have to be rolled around in water and gravel/sand for at least several weeks to become extremely rounded. Most rounded rocks became that way by tumbling in streams and rivers for many years.

Reply 283:
I hope they take pictures of these scoop areas later at the same time of day so the lighting can be more constant. That glare makes it difficult for me to compare.
I agree with you that there does appear to be dimming. Maybe its a compacted ice glazed material right after the scoop. As time goes by the ice material sublimates at the surface and becomes more fuzzier/dustier, and hence less reflective.

You can see something similiar to that with Earth damp dirt. If you were to scoop the right kind of Earth dirt or clayey dirt you would see a "smearing" on the scoop hole. The smearing is highly relective/shiny and may look like water or ice. This shiny smear usually goes away as the moisture within disappears or when it looses cohesiveness and erodes or crumbles.