[meteorite-list] NWA 6928 A Rare Noritic Diogenite meteorite

From: Gary Fujihara <fujmon_at_meteoritecentral.com>
Date: Thu, 08 Sep 2011 06:12:53 -1000
Message-ID: <899E09A2-404F-49F5-8541-610A62CF65AE_at_mac.com>

Aloha Bernd,

Well actually, my NWA 6927 is a very fresh orthopyroxenitic diogenite (Fs24.9-25.1Wo3.2-3.6; FeO/MnO = 30-33), with accessory olivine (Fa31.0; FeO/MnO = 43), troilite and chromite. One of the best of this 'flavor' of diogenites since my NWA 6421.
http://bigkahuna-meteorites.com/NWA6927.html

NWA 6928 noritic diogenite was indeed initially thought to be a eucrite by myself and Dr Tony Irving, who described it as a 'spectacularly fresh and very unusual basaltic eucrite'. The pyroxene is entirely orthopyroxene, and it is way more magnesian that anything else seen in eucrites. Further tests concluded that in no way can NWA 6928 be a eucrite, because the pyroxene is not pigeonite, but instead orthopyroxene (with a composition in the range for diogenites). It is composed of 80 vol.% orthopyroxene (Fs33.4-34.1Wo2.5-1.2; FeO/MnO = 31-33) and 19 vol.% interstitial, anorthitic plagioclase, with accessory Ti-Al-bearing chromite, troilite and merrillite with a relatively coarse grained, cumulate texture.

Truly an enigma, I've never seen a diogenite that looks quite like NWA 6928, and there are still a few slices left of this very rare (one of only three known noritic diogenites) meteorite.
http://bigkahuna-meteorites.com/NWA6928.html

I agree with you about ET's NWA 6693 thin sections - spectacular, and something I hope to have available soon on my own NWA 6926 ungrouped achondrite pairing to Greg Hupe's NWA 6704.

gary

On Sep 7, 2011, at 1:14 PM, Bernd V. Pauli wrote:

> Gary, I beg to differ ;-)
>
> NWA 2928 is that gorgeous plagioclase-rich eucrite, 9.78 grams
> of which will soon embellish my collection.
>
> The rare noritic diogenite meteorite, that's NWA 6927 and because
> this is such an extraordinary diogenite, I just couldn't help adding
> that beautiful 5.36 gr slice to my collection as well.
>
> Even though my wallet now looks like an empty hole, sometimes
> there are meteorites and thin sections that you just cannot miss
> out
> on!
>
> ... and that's why E.T.'s offer of NWA 6693 thin sections, perfectly
> prepared by the "one and only" slide maker in this world and at such
> an attractive price (considering the surface to price ratio) is another
> inevitable addition to my collection and a perfect one as well, as there
> is aready a 6.01 gr slice of the paired NWA 6704 from Greg Hup? in my
> collection!
>
> Can hardly wait to welcome these exotic beauties in my collection!
>
> Cheers,
>
> Bernd
>
>
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Gary Fujihara
Big Kahuna Meteorites (IMCA#1693)
105 Puhili Place, Hilo, Hawai'i 96720
http://bigkahuna-meteorites.com/
http://shop.ebay.com/fujmon/m.html
(808) 640-9161
Received on Thu 08 Sep 2011 12:12:53 PM PDT