I know, I know, I know: it's blue. Mafic igneous rocks reflect shorter wavelengths, so what? When they are powdered, they reflect more. So? Guess what, if they ever RAT gray hematite the powder is going to be red. That's right, red. Hema = red It's called a "streak test", geology 101, lab 1, diagnostic properties of minerals.

I suspect, aside from a fascination with the color blue, that you secretly think this means there is subsurface water. If so, forget about it. The rovers are not going to smash a rock like they are a robotic Moses and have a nice bubbling spring of evian water issue forth. Forgive me, I can be quite a smart-ass at times, but the blue tint has nothing to do with water or Blue Mars or anything like that.

If you've another thesis or model or observation about why mafic rocks on Mars have a bluish tint then out with it, I'll be happy to consider your opinions and throw in my two cents (or 25 cents). I've seen so many blue tinted mafic rocks in the desert it's not even interesting anymore. Okay, you say there is still some water in the deserts of the southwestern US, but if you want, spend your time looking for analogs in the high, oh-so-dry deserts of Chile and Peru. I don't have the time.

Furthermore, when you combine RGB channels you are constricting the bandwith of the filters even more and assigning them an artificial, constrained wavelength.

Thanks, though, our previous discussions prompted me to learn more about the pancam and related color issues. But I'm done with the color discussion unless you put your cards on the table. Unless, of course, it is to improve the Blue Man on Mars pic. I hope it made you chuckle at least a little bit.