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

[Michael Farmer]

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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