[Frank_Discussion]

I don't think iron oxide is magnetic. Along the same lines, though, a really fine dust might stick via static electricity. I am not really seeing that as the cause of this, however.

It looks darker than the surrounding soil, as if it is wet. We may have found a covered layer of liquid slightly below the dust.

I AM INTRIGUED!!

[templar]

We may have found a covered layer of liquid slightly below the dust.

Tar. Like in the La Brea Tar Pits.

[e_engineer]

a really fine dust might stick via static electricity.

Opposite charges attract each other, but once they touch, the charges neutralize. If there is still a net charge after they touch, the particles then repel one another. (Like charges repel).

[Doc On The Bay]

So the "Scientists" who launched the "Spirit Rover" had some Minor Problems with Their Bladders!

I'm SURE the "Problem will Soon be "Rectified!"

Doc

[gatex]

"...I don't think iron oxide is magnetic. --- It looks darker than the surrounding soil, ...."

Don't forget magnetite -- Fe3O4 -- a black mineral that is readily recognized by strong attraction by magnet (The Condensed Chemical Dictionary).

[Alas Babylon!]

I don't think iron oxide is magnetic.

Actually, Frank, it is. AKA Ferric Oxide, it's the stuff that coats magnetic tape and disk surfaces that allows us to write bits on them in order to do what we're all doing now....FReeping!

[asb3pe]

I don't think iron oxide is magnetic.

It isn't. That's why I prefaced the idea by saying "any remaining iron in the iron oxide".

I also thought about the static electricity idea, but similar to you, I rejected it as being a probably cause, as I just can't see that force holding soil particles together in clumps very well.

Perhaps the "dust" has good insulating properties, and perhaps there could be some sort of liquid just under the surface. In direct sunlight, the martian surface DOES warm up close to and even above freezing, I believe, at certain times of the year.

So... just how big would a quick discovery of some liquid just under the surface be? It would be HUGE! Discovery of microbial life would be almost certain to quickly follow, and that... I can't even fathom the reaction. But I am almost expecting it, because I do believe Mars once harbored life to some degree, and may still, to this day...