Some may recall the recent debate here over the "true color" of the martian surface feature known as "White Rock." Below is an excerpt from the Christensen et al. paper:

"An approximately true color visible image of the relatively bright enigmatic feature known as 'White Rock' in Pollack crater (8°S, 25°E) (Fig. 7) indicates that White Rock is actually quite red, consistent with previous lower-resolution Viking color imaging of this feature (28). Indeed, the actual color and reflectivity of White Rock is comparable to that of typical bright dusty regions on Mars, suggesting that it is either mantled by thin ferric-rich aeolian dust deposits or consists of weathered or coated ferric materials."