[meteorite-list] AD-Special: Premiere of a New Martian: - NWA 4925 - Olivine-orthopyroxene-phyric Shergottite

From: Michael Farmer <meteoriteguy_at_meteoritecentral.com>
Date: Sat, 5 Apr 2008 15:02:38 -0700 (PDT)
Message-ID: <79360.18777.qm_at_web33102.mail.mud.yahoo.com>

Wonderful new Martian meteorite Martin! It has been a
while since a nice new Mars rock hit the market.
I am still waiting for a large Martian meteorite fall,
that will be a dream come true if that happens.
Mike


--- Martin Altmann <altmann at meteorite-martin.de>
wrote:

> Dear Collectors,
>
> The presentation of a new Martian meteorite to the
> meteorite community is
> always an event.
> Such introductions of new lunaites and Martians are
> those moments that are
> most fulfilling in the life and work of a
> meteorite-addicted person.
> And we hope that you will share at least partially
> our exaltation about this
> new fabulous stone, named
>
> NWA 4925
> Purchased 2007,
> Morocco
> Tkw 282.3g
> o-SHE
>
> Understandably, we aren't really unbiased regarding
> our new Mars rock, and
> so we asked one of the best and most experienced
> connoisseurs of Martian
> meteorites, Norbert Classen, known also to be the
> author of one of the best
> homepages for lunar and Martian meteorites
> (http://www.meteoris.de/) for his
> opinion on NWA 4295, and we are much obliged that he
> allowed us to report
> his observations and his opinions about the new
> material:
>
> "Right now we know about 50 different, i.e. unpaired
> Martian meteorites,
> including 4 witnessed falls (Chassigny, Shergotty,
> Nakhla, and Zagami), 15
> Antarctic finds, and 31 hot desert finds, most of
> them having been recovered
> from the deserts of Africa. The majority of all
> Martian meteorites belongs
> to the class of mostly "enriched" basaltic
> shergottites, while the
> "depleted" group of olivine-phyric, and
> olivine-orthopyroxene-phyric
> shergottites are far less abundant. NWA 4925 belongs
> to the latter subgroup
> which consists of just about 5 different members,
> including the Dar al Gani
> shergottites, NWA 1195, NWA 2626, NWA 2046, and NWA
> 4527 (TKW 10g). NWA 4925
> is possibly paired with the latter one, but up to
> this moment no studies
> have been conducted to prove or disprove this
> suspicion that's only based on
> a comparison of overall texture, and weathering
> grade.
>
> Like NWA 1195 and NWA 4527, the new NWA 4925
> exhibits a pronounced light
> colored weathering rind, typical for desert finds
> with long terrestrial
> residence ages. Olivine phenocrysts near to or
> within the weathering rind do
> often show a bright red appearance, a sign that most
> of the iron within
> these olivines has been oxidized in the terrestrial
> environment. Overall,
> the matrix color within or near to the rind is more
> redish - reminding us of
> the same process that gives Mars its red appearance
> although most of the
> Martian rocks are originally of grey, or grey to
> green color. The interior
> of NWA 4925 is actually dark green, with shock
> altered dark-brown olivine
> phenocrysts set in a matrix of more fine grained
> greenish pyroxenes and dark
> maskelynite, both bearing witness for the fact that
> the interior of the rock
> is more or less pristine and fresh, just as if it
> left Mars only yesterday.
> It's that interesting contrast of the more
> light-colored weathering rind
> with its neat redish olivines, and the dark-green,
> very fresh interior that
> makes NWA 4925 visually most attractive, and
> scientifically interesting
> because it models the surface weathering on the Red
> Planet.
>
> >From the samples of NWA 4925 that I could study I
> would further suspect that
> the olivine and orthopyroxene phenocrysts show a
> preferred orientation like
> in NWA 1195, and other ol-opx-phyric shergottites,
> something which is
> indicative of magmatic flow prior to the cooling and
> solidification of the
> sample. Other most interesting features are melt
> inclusions, and small
> chromites that are enclosed into the large olivine
> phenocrysts. Overall, a
> very interesting, and optically most attractive new
> Martian meteorite of a
> rare class. A "must have" for any serious collector
> of planetary meteorites,
> and rare achondrites."
>
>
> Dear collectors,
> For us the acquisition of this new Martian was
> combined with various
> difficulties and we are glad and happy to have it
> finally in our very hands.
> Therefore we simply decided against all advice and
> economical reason to
> share our joy and to choose for this introductory &
> exclusive special
>
> a price of 400$ per gram!
>
> We hope for your understanding, that this offer will
> be limited for the
> pieces pictured on the special-page and for all
> other orders too (in case
> the special-specimens will be sold out) until Sunday
> next week; and that
> afterwards we will have to adjust the price to the
> more general Martian
> price-level.
>
> And here is the beef:
>
> http://www.chladnis-heirs.com/special-nwa4925.html
>
>
> Enjoy!
> Martin & Stefan
>
> Chladni's Heirs
> Munich - Berlin
> Fine Meteorites for Science&Collectors
>
>
>
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Received on Sat 05 Apr 2008 06:02:38 PM PDT