Marquette Island might be a meteorite afer all.

http://marsrovers.jpl.nasa.gov/gallery/pre.../20091125a.html

I'll be damned.

Makes me wonder if we've seen any rocks @ Meridiani that aren't meteoritic aside from the clearly native 'paving stones'.

Tell ya... Meridiani = meteorite hunter's paradise

I reckon it's a bit of Phobos. (Just a fun guess)

I wonder if it could be a meteorite that actually originated on Mars (ejected, later reentered).

See post 589. No answer yet about what is a meteorite.

You asked for it, my own expert opinion.

Any rock that has orbited any object in the solar system, including the sun, is a meteoroid. If it falls to the surface of any body in the solar system, it is a meteorite.

A rock on Mars could have been at one point a meteoroid that originated from Mars, but as it would be near impossible to distinguish it from other ejecta that fell back to Mars, the question of whether it is a Mars meteorite on Mars is moot. Unless...

Some way might be found to show a Mars rock had spent a long period of time in interplanetary space, I don't know.

If it is a Mars rock that spent some time in space wouldn't we know that from its composition? Ejecta would have still gone through the eons of Mars' surface climate?

Only thing I can think of is to check for iridium & other rare-earth enrichment, but dunno if the APXS is still capable of that (and, actually, don't know what the normal Martian baseline values are for rare earths...)

If that's possible, might at least eliminate it as surface ejecta (whenever/wherever that would have happened). I can't think of any tests that Oppy could do to tell if it was a Martian rock that spent time in space before re-entering.

If it is not Martian, then could it be still a piece of the impactor that caused Fresh crater or is there no chance that single pieces can survive the impact? Shouldn't a single stony meteorite still show a bit of the hardened crust from the entry? At least, it should then have another look from the "weathering".

Bounce has the composition of a typical Mars meteorite. However on Mars Bounce is not a meteorite because it is still on the planet that it originated from.

It may be my impression but...didn't Oppy just put Marquette to the floor with a might uppercut?...
http://qt.exploratorium.edu/mars/opportuni...R5P1110L0M1.JPG

EDITED: Yes, just my impression...where did I put those glasses?

We can see many smaller fragments of similar looking rock scattered around, so presumably MI isn't the entire original impactor. If we're lucky and it hasn't eroded away maybe pieces of the original entry surface are still on some of the fragments around though.

As I understand, Bounce is not a meteorite because it presumably has never been in orbit. But suppose it had. Bounce is suspiciously similar to some Mars meteorites on Earth. It's possible that the same impact that sent Bounce to land in Meridiani also sent some fragments into solar orbit which eventually landed on Earth. Perhaps it's also possible that some fragments that were in solar orbit also fell back to Mars, not that Bounce is one of those.

The official scientific definition of "meteorite" could include the provision that a rock , even after millions of years of solar orbit, that falls on the planet of it's origin is not a meteorite. But I don't know that it does. The question is probably moot. But if it could be determined that a rock from mars spent millions of years in solar orbit before falling back to Mars, why would you not call it a meteorite? It certainly has a history which is much different from the typical Mars rock.

Or, a piece of deep ejecta: