[meteorite-list] Mercury Meteorite Puzzle

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:04:49 2004
Message-ID: <200205161738.KAA26644_at_zagami.jpl.nasa.gov>

http://news.bbc.co.uk/hi/english/sci/tech/newsid_1991000/1991394.stm

Mercury meteorite puzzle
               
Is this from Mercury, the planet closest to the Sun?

By Dr David Whitehouse
BBC News
May 16, 2002

The first meteorite that may have come from Mercury has been
identified.

NWA 011 was found in the Moroccan Sahara in December 1999
and was immediately regarded as something unusual.

It clearly had a molten past and was formed from lighter materials
than most meteorites. This implied it had once been part of a much
larger body.

It was originally classified as a eucrite, a group of meteorites thought
to be from the asteroid Vesta. But a detailed analysis of NWA 011
showed it to be different.

Now, researchers speculate that it is the first known meteorite
from our Solar System's innermost planet, Mercury.

Rocks blasted off Mercury by a large impactor would have a
difficult journey to reach the Earth, say the researchers - but
not impossible. Nevertheless, the calculations show such rocks
would be an extremely rare find on Earth.

NWA 011 has an oxygen isotope ratio that indicates it came from
a body larger than a big asteroid. Japanese researchers say the
basalt in NWA 011 suggests the body from which it did originate had a
core of molten iron with an outer covering of silicon and aluminium
that formed a basaltic crust.

And that means a planet-sized body. Could it really be Mercury?
Received on Thu 16 May 2002 01:38:56 PM PDT