[meteorite-list] Zaklodzie-Like NWA 4301 Description

From: Greg Hupe <gmhupe_at_meteoritecentral.com>
Date: Tue, 24 Mar 2009 13:45:59 -0400
Message-ID: <1BA356DC58F142E19AC5928F303D709E_at_Gregor>

Dear List Members,

It is my pleasure to offer a new meteorite that I have had for nearly three
years. It is one of those great head-scratching, mind-boggling meteorites
that makes one say, "How is that?!"

NWA 4301, a Zaklodzie-Like Ungrouped Enstatite-rich Achondrite found in
Algeria in 2006 by nomadic tribesman. NWA 4301 is nearly identical to
Zaklodzie, both in mineral composition and terrestrial age, about 300 years
(The same scientist at NSF Arizona AMS Laboratory measured the terrestrial
age dates of both meteorites). If they had not fallen 3000 km apart, NWA
4301 would have been considered a pairing. While that is unlikely,
scientists agree they are most likely source launch-paired! The Total Known
Weight of NWA 4301 consists of a single 685 gram stone.



Close-up view of polished slice of NWA 4301 (depth of field = 2cm across):

http://www.lunarrock.com/nwa4301/nwa4301closeup.jpg



Scientists write:

"This meteorite [NWA 4301] is essentially a clone of Zaklodzie, for which .
a very young terrestrial age of several hundreds of years [was found] (even
though it is weathered to some extent). I presume that the terrestrial ages
of these two are analytically distinguishable, but it could still be that
they are launch-paired."



"NWA 4301 seems much fresher than Zaklodzie."



"I believe that the [terrestrial ages] are permissive of both stones being
part of the same fall, but landing 3000 km apart in Poland and Algeria. Of
course there is a very large uncertainty, so it does not prove it, but the
two meteorites are remarkably similar and different from anything else."



Approved classification published in Meteoritical Bulletin 91 for NWA 4301:

Northwest Africa 4301

Mauritania or Algeria

Find: April 2006

Enstatite achondrite (ungrouped)

History: Purchased in April 2006 by G. Hup? from a Moroccan dealer in Rabat.

Physical characteristics: A single 685 g stone with some reddish external
weathering.

Petrography: (A. Irving and S. Kuehner, UWS)

Subequigranular igneous cumulate texture with relatively coarse-grained
(0.2-0.8 mm) silicate, metal, and sulfide grains. Composed mainly of
polysynthetically twinned pure enstatite = 70 vol% and kamacite = 15 vol%,
with subordinate interstitial plagioclase = 10 vol% and troilite = 5 vol%.
Micrometer-size blades and blebs of kamacite and rare daubreelite also occur
as inclusions within enstatite.

Mineral composition: Plagioclase (An30.7-37.6Or1.8-1.3).

Classification: Enstatite achondrite (ungrouped). Terrestrial weathering has
produced some limonite along grain boundaries. This specimen is very similar
in texture and mineral compositions to Zaklodzie.

Type specimen: A total of 22.9 g, one polished thin section and one polished
mount, are on deposit at UWS. G. Hup? holds the main mass.



I will be making NWA 4301 available and will send a follow-up post which
will have the limited amount of available specimens.



Best regards,
Greg

====================
Greg Hupe
The Hupe Collection
NaturesVault (eBay)
gmhupe at htn.net
www.LunarRock.com
IMCA 3163
====================
Click here for my current eBay auctions:
http://search.ebay.com/_W0QQsassZnaturesvault
Received on Tue 24 Mar 2009 01:45:59 PM PDT