[Curiouserand (OP)]

I'm no geologist, but wouldn't mind knowing what the experts here think could be contained in this scoop of martian soil?

[CliffordK]

You may well have other minerals present such as copper or nickel.

Here is a photo of nickel Ore.
http://www.agrofurniture.com/content/nickle-ore
and copper ore
http://campus.hesge.ch/commodity_trading/wp-content/uploads/2012/10/copper1.jpg

Note in the chemical analysis for the nickel sample above, there is a mix of minerals with more iron than nickel.

[CliffordK]

Looking at the Mars photos a little more.

The rock is being called grey.

Looking at these two photos side-by side, the borehole, and the pulverized rock.

http://news.yahoo.com/red-planet-mars-not-red-beneath-surface-053603986.html



The rock in the scoop looks much greener than the source.

HOWEVER,

The background rock with the scoop looks redder than in the other photo, and even redder in your photo.

My guess is that it is a color balance issue.

I'm surprised that they don't put a scale and color bar in every photo, although to do it effectively, they would need a robotic arm dedicated to placing the scale and color bar in appropriate places. 

They could have, however, designed the scoop, and other parts of the rover with a built-in color bar.

I would also like to see them clean out the hole and take a well-lit closeup of the actual rock core/hole.

[Curiouserand (OP)]

Thanks CliffordK
it hadn't occurred to me that it could be a colour saturation issue. Thanks for the reply.

[Mazurka]

It could also be to do with the oxidation state of the iron.
Marlstone formations (e.g. Blue Anchor formation)  such as those seen on parts of the South Wales coast near Cardiff, can show distinct red and green beds.  The green beds were formed in low oxygen conditions. 

[CliffordK]

I tried to digitally correct the color. 
I could make everything more pastel colored, but still ended up with a pastel green.

I could, of course, correct the green to grey, but that messed up the redish background.

I do think the borehole may also have a slight green tint to it, so I wouldn't be surprised to find some copper, nickel, or perhaps other minerals in the rock.

I do find it interesting that the rocks are only red on the outside.  From dust?  Some equivalent of dusty mud?

[Lab Rat]

It could be that the colors are different because many minerals are different colors depending on whether they are solid or in powder form-just like a streak test.

[Atomic-S]

I wonder to what extent Mars' red color is simply a surface condition.

[Atomic-S]

The greenness under the redness is a surprising and interesting occurrence. Maybe Mars is the green planet, not the red planet. As for why this strange coloration:  It is worth noting that iron compounds exist in both green and red, and that the green compounds are typically associated with the ferrous (+2) oxidation state, but the red is associated with the ferric (+3) oxidation state.  So, an initial speculation would be that Mars soil is basically ferrous, but that it rusted to the ferric state on the surface.  Of course, if that is so, it is undoubtedly significant in terms of understanding what sort of conditions existed on Mars in the past.

[evan_au]

A light-coloured rock "suddenly" appeared in 2 Mars rover images taken 2 weeks apart. It has been dubbed "Pinnacle Island" if you are searching for updates.

If it was flipped over by the rovers wheels (rather than being a meteorite fragment as others surmise), it may represent a general lighter colour of Mars rocks that haven't had long-term Sun/Atmosphere exposure?

...and then there is the man in California who is suing NASA - he says that they need to investigate this native fungus.