AW: [meteorite-list] K20 in meteorites

From: MexicoDoug_at_aol.com <MexicoDoug_at_meteoritecentral.com>
Date: Wed Jun 23 13:45:53 2004
Message-ID: <51.40498df7.2e0b1bc5_at_aol.com>

Michel & J?rn,

I have no access to those references so, just wanted to ask is it conceivable
that the analyses reflect potash-type runoff or contamination from:

a) concentratin by long since evaporating ancient lake beds (like hot
desert-low elevation in Tunisia, maybe?)
b) concentration by evaporating water deposits (like Mars, maybe)
c) from fertilizers' runoff (including simoon) ?

Saludos Doug

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

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Joern Koblitz
MetBase Editor
The MetBase Library of Meteoritics and Planetary Sciences
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> -----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 at 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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> Meteorite-list at meteoritecentral.com
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>


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