[meteorite-list] Mercurian Meteorites (was: Rocks from Space Picture of the Day - June 16, 2010)

From: Greg Catterton <star_wars_collector_at_meteoritecentral.com>
Date: Fri, 18 Jun 2010 09:55:58 -0700 (PDT)
Message-ID: <294341.31874.qm_at_web46412.mail.sp1.yahoo.com>

Iron in meteorites is a funny thing also... it may come from impacted material that forms breccias.
NWA 5000 has a nice amount of iron in it for a lunar.

There are many awesome PDFs about angrite meteorites here:
http://www.lpi.usra.edu/search/?cx=002803415602668413512%3Acu4craz862y&cof=FORID%3A11&q=NWA+2999&sa=Search#1307

Greg Catterton
www.wanderingstarmeteorites.com
IMCA member 4682
On Ebay: http://stores.shop.ebay.com/wanderingstarmeteorites
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--- On Fri, 6/18/10, bernd.pauli at paulinet.de <bernd.pauli at paulinet.de> wrote:

> From: bernd.pauli at paulinet.de <bernd.pauli at paulinet.de>
> Subject: [meteorite-list] Mercurian Meteorites (was: Rocks from Space Picture of the Day - June 16, 2010)
> To: Meteorite-list at meteoritecentral.com
> Date: Friday, June 18, 2010, 12:47 PM
> Greg S. inquired:
>
> "I heard that possible meteorites from Mercury should
> contain very little
> (or no) free iron. Is this true? I think the one pictured
> here and NWA 2999
> do contain some free iron."
>
>
> Hello Greg and List,
>
> I thought this summary of the "Summary and Conclusions"
> part of Love's article
> might be of interest because it partly answers your
> question about Mercury's iron:
>
> Summary:
>
> - orbital evolution of Mercurian material to Earth-crossing
> orbits possible
> - efficiency probably < 1% of that computed for Mars
> - a ~ 10% chance that a mercurian rock could exist in
> current meteorite collections
> - may possess an unusual isotopic composition
> - rocks from Mercury probably low in volatiles
> - Mercury bulk composition moderately enriched in
> refractory oxides of Al, Ti, and Ca
> - FeO contents not more than ~ 5%, and possibly much lower
> - Mercurian regolith breccias:
> ? - rich in micrometeorite craters
> ? - rich in exogenic chondritic materials
> ? - rich in agglutinates
> ? - rich in impact vapor deposits
> ? - lower solar-wind content than similar lunar soils
> ? - implanted gas may be fractionated by interaction
> with Mercury's global magnetic field
> - a uniquely high solar-to-galactic cosmic-ray damage track
> ratio of surfac rocks
> - launch-induced shock damage may be comparable to or
> greater than in martian meteorites
> - no match of these predicted properties of mercurian rocks
> in current meteorite groups
> - misclassified mercurian meteorites most likely
> differentiated, low-FeO objects such as
> ? lunar anorthosites and aubrites
>
> Reference:
>
> LOVE S.G. et al. (1995) Recognizing mercurian meteorites
> (MAPS 30-3, 1995, 269-278).
>
> .........................................................................................
>
> There are some scientists who favor enstatite chondrites
> but there's a problem with that:
> Mercury's mean density is about 5.4 g/cm^3, whereas
> enstatite chondrites have a density
> of about 3.4-3.7 g/cm^3.
>
> In 2002, H. Palme proposed that NWA 011 (and paired
> material like NWA 4587) might be
> a fragment of Mercury but the high FeO content of this
> meteorite would point toward
> a parent body with a small metallic iron core. Mercury,
> however, is believed to have
> a large iron core.
>
> Best wishes,
>
> Bernd
>
>
>
>
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Received on Fri 18 Jun 2010 12:55:58 PM PDT