Mimi: visual notes

OBSERVATIONS:

The specimen displays thin layers that appear to be primary. The layers are not of uniform thickness and appear to be sub-parallel and discontinous. Lowermost layer is thicker with rounded pinch and swells. The uppermost layer appears massive. A few rounded "pebble like" areas concordant with layering on upper horizontal surface. Portions of the rock are the same color as nearby, probably basaltic, rocks. There are apparent vesicles (or other small pits) in the upper portion. There is a dust covering over much of the exposed surface.

COMMENTS:

A view parallel to layering is eagerly awaited.
Might be an analog in the 'specimen wall' in Hawaii.
NOT a metamorphic rock. (slate, phyllite, schist, gneiss) !
-I've never heard that plate tectonics ever developed to the point of creating regional metamorphic rocks on Mars (not talking about shock metamorphism)-
NOT a mudstone, sandstone, siltstone... (no obvious clastic or chemically precipitated textures)
NOT biotite. (wrong scale, layering not mineral cleavage, never seen a book o' biotite this big...)
Layering probably not related to impact. Perpendicular (to layering) cracks may be a result of impact (or not).
Did they call it Mimi for the blue eye shadow?

FIRST GUESS:

1. Flow basalt
2. tuffaceous basalt

Basalts can take on some diverse morphologies. Massive, pillowed (now that'd be cool!), blocky, ropey, and more. Pretty fluid stuff when molten, not like the more siliceous andesites and rhyolites.

Laugh all you will, but the Hawaii analog is justified. I want to see this specimen wall in Hawaii! Geology depends on such observations. Geo 101: Law of Uniformitarinism. Adjusted to Mars, of course.

HOWEVER:

Sedimentary rocks derived from volcanic terrains with minimal transport distance can be decieving, even geochemically. (probability rating: 0.66%)

OFF TOPIC:

The articles Gary linked are great, worth the download. No data about Opportunity outcrop, though. Sigh. I'll post a review if I've the time...