Indeed, infact a thought occured to me that it may be possible to derive hardness on the Moh's scale using RAT data (although Im sure there is a value somewhere ). Comparing voltage from RAT operations from Spirit and Opportunity, one can see that Spirit was the one doing the real work (that's basalt for you!)

Stu's latest post has inspired a limerick:

Our site has a wonderful poet,
But he's also a pol, don't you know it?
"If I speak of the layers,
T'will bring out the brayers --
So it's better for all just to show it!"

Thanks Mike - appreciate the reply. I'm off on a long bush trip from Alice to the Kimberleys via Perth (!) tomorrow so I can enjoy reading Sullivan/Mangimeli papers etc. on the plane!!

Sometimes Mars itself seems to present us with a beautiful, natural composition...

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