AW: [meteorite-list] K20 in meteorites

From: Jörn Koblitz <koblitz_at_meteoritecentral.com>
Date: Wed Jun 23 12:26:21 2004
Message-ID: <E5E6112EA31FA24CB448E091C6883C050EBC45_at_server2000.microfab.de>

Dear Michel,

fairly high K2O values have been reported for C-like clast in the following meteorites:

LEW 85300 (polymict eucrite) 0.47% (C clast)
Supuhee (H6) 0.57% (clast)
Kr?henberg (LL5) 1.45% (dark portion)
Miles (IIE silicated iron) 0.5% (silicates)
Cumberland Falls (aubrite) 0.43% (chondritic clasts)

but also as bulk content:

Governador Valadares (nakhlite) 0.43%
Bhola (LL3-6) 1.5% (reference: Compositional study of K-rich fragments and host material, pyroxene Fs4-25, olivine Fa27.8,
                                       F.Wlotzka et al., GCA, 1983, 47, p.743.)

There are some more meteorites with high potassium contents reported, but the wet chemical analyses are fairly antique and not very trustworthy.

To give a general direction: high potassium contents in whole rock material is quite unusual. Typical contents are in the order of 0.1 to 0.2% for chondrites and 0.02 to 0.05% for basaltic achondrites (grand average of 1660 analyses is 0.098%). High K values have often been reported for unusual clasts in achondrits as well as for chondrites (here mainly carbonaceous material) and silicated irons. So, it could be, that your meteorite is a clast left over (e.g. by weathering or fragmentation during fall) from a larger body.

Best regards,
Jorn

_______________________________________________________________________________
Joern Koblitz
MetBase Editor
The MetBase Library of Meteoritics and Planetary Sciences
Benquestrasse 27
D-28209 Bremen, Germany
phone: +49 421 24 100 24
fax: +49 421 168 2799
email: info_at_metbase.de
_______________________________________________________________________________





> -----Urspr?ngliche Nachricht-----
> Von: Michel Franco [mailto:michel_at_caillou-noir.com]
> Gesendet: Mittwoch, 23. Juni 2004 17:20
> An: meteorite-list_at_meteoritecentral.com; bernd.pauli@paulinet.de
> Betreff: [meteorite-list] K20 in meteorites
>
>
> Hello Bernd, & List
>
> I have a problem with my new find Sahara 03500. ( Achondrite anom) :
>
> It holds more than 0.5% of K2O. Other percentages are almost OK.
>
> I am wandering if other meteorites hold such percentages of
> that Potassium
> Oxyde, which is 5 times more than any average type.
> Any answer or help is welcome. TKS per advance.
>
> Best regards
>
> Michel.
>
> Photo of this rare meteorite on my site at
> www.caillou-noir.com/TassaMahchi.htm
>
>
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Received on Wed 23 Jun 2004 12:16:21 PM PDT