[meteorite-list] Re: Mercury Meteorite Puzzle

From: Starbits_at_aol.com <Starbits_at_meteoritecentral.com>
Date: Thu Apr 22 10:04:50 2004
Message-ID: <137.e6947b8.2a1b0799_at_aol.com>

In a message dated 20-May-02 1:54:37 PM Pacific Daylight Time,
baalke_at_zagami.jpl.nasa.gov writes:

<Since the planets are formed from chondritic asteroids, I don't think you can
 rule them out just because the meteorite is a chondrite.>

So are you proposing that there is remnant chondritic material on earth from
its formation 4.5 billion years ago? Although the specifics maybe different
Mercury and Venus formed through the same differentiation/core formation
process as earth. The probability of remnant chondritic material on Mercury
and Venus is about the same as it is for earth.
 
<Since the olivine crystals are only found in an iron matrix, that should
 be your first big hint. >

Could be, except that olivine is found as massive formations of large olivine
crystals without an iron matrix, just not in meteorites. One notable
location
is the San Carlos Apache reservation where unaltered mantle material
was erupted to the surface. It is now mined for gem quality olivine,
commonly
known as peridot. So the question remains if there are olivine crystals 60
to
100 kilometers deep on earth (the depth of the peridot source) why haven't
we found meteorites composed of just olivine crystals? There is no currently
accepted answer.

Somewhere I have some of this mantle material from Kilbourne hole in southern
New Mexico. If I can find it I will post a picture tomorrow.

Eric Olson
http://www.star-bits.com
Received on Mon 20 May 2002 10:14:49 PM PDT