re: What kind of rock does Mimi look like to you geologist types?
How is the flakey debris -- both above and below 'Mimi' -- related if at all?
It looks like the rock may have come to pieces almost explosively. What could cause that? Ice? Impact?
I'd keep options open.
However, it doesn't look like this particular rock belongs here, unless the other rocks in the scene would also 'explosively' disintegrate. Wouldn't that be fun! (It's worth noting that many of the rocks examined in Gusev appear to be layered or coated in some interesting manner.)
Are there other rocks similar to 'Mimi' nearby?
Not enough information!
Cheers, BR