[meteorite-list] Mica in meteorites.

From: Treiman, Allan <treiman_at_meteoritecentral.com>
Date: Sun, 25 Feb 2007 20:10:28 -0600
Message-ID: <7C188E1BAB399F4897C1F743DCD71836E9840A_at_exch_be.cass.loc>

Hi, list -

   I've had the great opportunity to work on a chondrite
with phlogopite - the R chondrite LAP 04840. This weirdo
has ~ 15% of amphibole, and about 1% phlogopite along with
the usual olivine and pyroxene.

http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1309.pdf


   Funny things are everywhere!

 Allan Treiman
 
P.S. Biotite mica includes the Mg-rich end-member phlogopite,
   and the Fe-rich end-member annite.

-----Original Message-----
From: meteorite-list-bounces at meteoritecentral.com on behalf of Mr EMan
Sent: Sun 2/25/2007 5:03 PM
To: bernd.pauli at paulinet.de; Meteorite-list at meteoritecentral.com
Cc:
Subject: Re: [meteorite-list] Mica in meteorites....was Comet McNaught andSodium


--- bernd.pauli at paulinet.de wrote:
> The CV3 chondrite Grosnaja contains sodium
> phlogopite, a phyllosilicate

Well if this is so, a long standing "factoid" in the
world of meteorites falls with this finding: "Mica
does not occur in meteorites".

Seems some meteorites DO contain mica, and a mineral
species of mica that would not have been anticipated
in Bowen. The micas biotite and muscovite appear in
Bowen's reaction series while philogopite does not
(given normal availability of iron). Only in an iron
poor setting does philogopite form. In this case a
potassium substitution by sodium has also occurred.

Phlogopite (K,Mg3AlSi3O10 (F,OH)2)is the end member of
the phlogopite biotite series of mica-- usually
associated with metamorphism of marbles, igneous
intrusions such as kimberlites of diamond fame, or
found in certain magnesium rich pegmaties-- even in
basalt. These are not the sources one thinks of for
carbonaceous meteorites.

Elton
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Received on Sun 25 Feb 2007 09:10:28 PM PST