[meteorite-list] What are those rocks on Mars?? one more opinion

From: j.divelbiss_at_att.net <j.divelbiss_at_meteoritecentral.com>
Date: Thu Apr 22 10:32:01 2004
Message-ID: <011320041516.22991.575a_at_att.net>

Hello all,

I'm back from the edge you might say. I've been quite ill to say the least,
but hopefully now on the road to recovery. I'm glad to be back on the list.

The latest pics from the Spirit are truly awesome. Many of you have hoped and
dreamed that many/most of the dark rocks in these pictures are fusion crusted
meteorites. Personally, I doubt if many of them are meteorites. To me they
look basaltic(extrusive igneous) or gabbro-like(intrusive).

I have a fair amount of field experience collecting ancient(1.6 billion)
intrusive-magma formed rocks from the gabbro family here in Eastern PA. In
particular these rocks in the Mars pictures look like a fine-grained iron
rich gabbro called metadiabase. Which is a black/dark green rock that
weathers to a rusty brown on the outside here on earth. They fragment into
both squarish blocks, and conical/rounded pieces over time. On Mars they
probably do not weather as much, thus they remain dark on the exterior, and
the winds and dust probably do a good job of rounding off edges over time
when exposed.

I know that the majority of the Mars meteorites we have recovered on earth
are not dark basaltic rocks, but more of a lighter colored rock. Many of you
(Norbert and others) have kept me straight on the concept that our Mars
meteorites are extrusive basaltic types.

But if the rocks on Mars are iron rich (helping to create the Red look), then
it is my understanding that they should also be dark rocks, and not what we
think of as a Mars basalt(ie: Zagami, etc.).

My guess is the rocks in these pictures are chunks of basalt flows or exposed
gabbro fragments like metadiabase, and not meteorites.

Any opinions to this recovering sicko rockhound are welcome? I'm back...I
think.

John

 
  
Received on Tue 13 Jan 2004 10:16:19 AM PST