[X] My Assistant

[Phillip]

Back on August 14, Squyres said:

"We're done with our work in the Voltaire region, having just finished up a pretty thorough IDD investigation of a rock called Assemblee. This thing turned out to have a crazy composition, with by far the highest levels of chromium that we've ever seen on Mars."

Does anyone have any thoughts on what the high levels of chromium tell us? Not being a geologist, I tried to investigate via googling, but came up empty. I would be interested in hearing some thoughts, conjectures or theories.

[ElkGroveDan]

Does anyone have any thoughts on what the high levels of chromium tell us? 

Heavy metals will accumulate in runoff basins, particularly at the base of higher mountains. Death Valley is a perfect example. The water runs to the lake at the bottom of the valley and then has nowhere to go. It evaporates and leaves all the dissolved metals and minerals behind. It's also a reason not to lick the salts you find in desert basins. They are usually high in toxic heavy metals.<p>

It is possible that this high-chromium rock could have once been part of the evaporite deposits collected in a runoff basin. If so it would be from the very earliest history of the Columbia hills, prior to their deposition or uplift.