[Texans]

Reading it for the first time, but I think the trenching could have caused the smoothing of the rock ?

[RightWhale]

I think if they adjust the gamma correction of the image processor, the range of brightness contrast won't be so great. That is, the brightness is probably artificial to a degree.

[JasonC]

My first thought too. Somewhat metallic nodules, only shiny because the rover's wheels "buffed" them up. Don't know, though, that's just a guess.