Comanche Options

[CosmicRocker]

I noticed them, too. I think Bill is correct. We've occasionally seen these things in previous MIs and even other cameras. My best guess is that these are specular reflections from shiny surfaces, quite possibly from some tiny crystal faces of the minerals comprising the rock.

If I had noticed such glints while inspecting a rock on earth with my hand-lens, I'd focus in on the spots to see if I could recognize the mineral.

[Shaka]

I noticed them, too. I think Bill is correct. We've occasionally seen these things in previous MIs and even other cameras. My best guess is that these are specular reflections from shiny surfaces, quite possibly from some tiny crystal faces of the minerals comprising the rock.

Would you see such "sparklies" in earth-bound basalts? Or are we seeing some kind of appended salt crystal?
Shame we can't 'rat' this sucker and get some fresh views. It could be a real Christmas decoration! I hope they TES it anyway, before we head for the "abyss"

[CosmicRocker]

If the light is right, you might expect to see specular reflections from almost any clean rock surface, since most are composed of the cemented grains of individual mineral crystals. I'd be surprized if this was a basalt, though.

It could be a salt crystal, but it could really be most any kind of crystal. There's no telling, and no way to know what it is with the instruments available on the rover. All we can know is that it is a flat, reflective surface that sent a ray of sunlight into lens of the camera.

[Bill Harris]

I doubt that the "crystal" is a salt. When I said "salt deposit" I meant more of an efflorescence, which I frequently see where mineralized phreatic water evaporating through a porous sandstone. I doubt that is happening here, but this was my first impression.

I've seen these strong mineral grain reflections many times, and this is puzzling to me since my mental image of Martian rocks is dusty and abraded and there _shouldn't _ be fresh surfaces. Nonetheless, they show up occasionally and I need to remove my blinders...

Once we know what the rock is we'll be able to make shrewd guesses as to what the crystal likely is.

--Bill

[abalone]

I doubt that the "crystal" is a salt.  .

I've seen these strong mineral grain reflections many times, and this is puzzling to me since my mental image of Martian rocks is dusty and abraded and there _shouldn't _  be fresh surfaces. 

Could be sapphires or rubies?, on Earth they are usually associated with basalts of some type. Unlikely but possible. More likely if not salts, to be rutile or ilmenite as some of the rocks are high in titanium and these are hard, weathering resistant minerals already identified in previous analysis I think??

[mhoward]

Pancam coverage to the northeast:



Happy Holidays!

[Phil Stooke]

I'm returning to this thread to add a few polar projections from the approach to Comanche. They are all derived from the always excellent panoramas of jvandriel. I especially like the large area of bright bedrock on sol 693.

This first one is sol 692, downhill from Miami.

Phil

[Phil Stooke]

Here's sol 693. I really look forward to seeing detailed stratigraphic mapping of this area from stereo images. Hard to believe there's so much exposed bedrock.

Phil