My apologies to all, I posted my earlier musing before reading all the press release data. I think I have some answers.

1. Bounce isn't *that* bright. The Meridiani soil really is that much darker than general Mars dust. If you look at the pancam spectra, Bounce is only moderately brighter than the "bright dust" unit, and a total albedo of .25 or .3 or so. Medium grey, not "white". A slightly reddish grey, even.

2. But, Bounce is not an ordinary basalt. Even if not bright, it is still lighter than the average basalts seen at Gusev. But, that seems explainable given its composition. Seems my mention of Steens Basalt was right on, Bounce is pretty high in (light colored) plagioclase -- 20%, which I gather is fairly plag-rich for a basalt.

I'm not sure what the petrologic significance of that is. If I understand correctly a basalt rich in plagioclase crystals could indicate perfectly ordinary mafic magma that stalled underground for a while and fractionated a bit, with layers near the top becoming rich in crystallized plagioclase.

Other ways to become plagioclase enriched?

3. Bounce sure seems like a good match to the Shergottites. Really worth looking at all the data they have in the press release. Even looking at the pictures vs the pancam and MI images, seem like very good matches.

4. Current thinking is that EETA79001 is YOUNG. As in, ~180 Ma. If there was volcanic activity happening near Meridiani only 180 million years ago, that's really quite recent (though I thought the crater count put the region older?).

But, there is an important debate on the ages, and EETA79001 might be the Rosetta stone for that. Apparently, part of that metorite (the "B" part) is a basalt like Bounce, the other part ("A") is generally accepted as an impact melt.

The problem is that A and B show the same age, to some researchers at least. Barring the truly amazing coincidence of a large impact just after the volcanism, the most reasonable explanation is that the impact reset isotopic clocks, contrary to most assumptions. Then, the 180Ma date for the SHergottites is for the impact (or an impact, maybe one that melted older rocks, and then yet another impact kicked the rocks into orbit millions of years later), not their original formation. If so, it raises some questions about the dating of all the young-seeming Mars meteorites.

OK, enough ramblings for now!