[meteorite-list] troilite euhedral crystals

From: Zelimir Gabelica <Zelimir.Gabelica_at_meteoritecentral.com>
Date: Sat, 13 Jan 2007 17:57:36 +0100
Message-ID: <5.0.2.1.2.20070113174449.027acd18_at_pop.univ-mulhouse.fr>

Yes Dave, I know (as a chemist since the late 1960'...).
Though I would expect that troilite would more rapidly react with HCl than
a more complex sulphide of (Fe,Ni,Co) (but this is just a guess, I never
tried a test reaction).

Now, these crystals most probably represent a sulphide commonly found in
OC's but that underwent far more dramatic (at least different) treatment
conditions in space (in terms of ageing and perhaps "passivation" towards
an oxidative of acidic aggressor) than on earth (just a speculation).
What is sure is that it is metallic (luster), thus most probably sulphide
and not elemental nickel (very unlikely).

I will neve accept treating these beauties by HCl just to check what they
are. I prefer to opt for some physico-chemical micro- and non destructive
technique (experiments planned for future as we wish to perhaps publish
these findings).

And, above all, I wish to preserve this beauty.
What an archive for extraterrestrial materials (heritage) so far so poor in
crystals (but wait for future planetary explorations....)

Zelimir


A 16:43 13/01/2007 +0000, vous avez ?crit :
>Hi Zelimir
>
>Superb!!! A splash of HCl on them and the resulting odour of bad eggs will
>confirm if it is a sulphide or not!
>
>As a terrestrial mineral collector i'd certainly want one of these vuggy
>crystallline slices in my collection!
>
>top pics!
>
>
>Best!
>d.
>
>-------Original Message-------
>
>From: <mailto:Zelimir.Gabelica at uha.fr>Zelimir Gabelica
>Date: 01/13/07 16:39:09
>To: <mailto:entropydave at ntlworld.com>Dave Harris;
><mailto:meteorite-list at meteoritecentral.com>metlist
>Cc: <mailto:bernd.pauli at paulinet.de>bernd Pauli;
><mailto:gary at webbers.com>Gary K. Foote; <mailto:warinroger at yahoo.fr>warin Roger
>Subject: troilite euhedral crystals
>
>Hello Dave, Gary, Bernd, Roger, list
>
>Dave, I am glad youthese mentioned euhedral (pyritohedral) troilite crystals.
>
>Well, I formely cut a Sierra Colorada (Argentina, L5) and two of the slices
>obtained contained large (almost centimetric) vugs, some making the 3 mm
>thick slice hollow!
>Looking inside is again really breathtaking.
>Several 5 to almost 10 mm (!) euhedral metallic crystals (also pyritohedral
>in shape) can be seen, aligned or dispersed, some as quasi isolated single
>crystals, onto the vug walls.
>One of them is sectioned through cutting and that small cut face (clearly
>seen on 2 pictures) indiceted to me, from the typical luster of the cut
>section, that these could be schreibersite (also possible, though perhaps
>less likely than troilite). See pictures 4741 and 4744.
>
>This is as spectacular as looking into a geode of a terrestrial mineral
>(although I have never seen terrestrial schreibersite, if ever it exists,
>because phosphides should readily yield phosphates in contact with air).
>
>My friend Roger Warin, not only expert in taking spectacular pictures of
>thin sections (see some preceding posts), was also able to realize superb
>close-ups of these geodes and "schreibersite" crystals.
>I have no web site to store these peictures for the list but I am enclosing
>5 of them as attachments for Bernd, Dave, Roger and Gary .
>
>Should perhaps Gary find a way to put them on his URL and send the link to
>the list, this wouild be just great!
>Thanks!
>
>Pleased to read your comments.
>
>Take care,
>
>Zelimir
>
>
>A 16:13 13/01/2007 +0000, Dave Harris a ?crit :
> >Hi,
> >My Mt. Taz definitely has euhedral crystals in the vesicles - unfortunately,
> >my binocular microscope only magnifies to about x35 or so and they are very
> >small (very sub-mm ) but become apparent when the specimen is tilted and the
> >light glints off the faces.
> >
> >The structure is typically pyritohedral in shape - I am assuming (a
> >dangerous thing to do) that these are Troilite xls.
> >
> >..and I never got a response as to what gases made the vesicular structure!
> >
> >
> >Best
> >
> >
> >
> >Dave
> >IMCA #0092
> >Sec.BIMS
> ><http://www.bimsociety.org>www.bimsociety.org
> >______________________________________________
> >Meteorite-list mailing list
>&<mailto:gt;Meteorite-list at meteoritecentral.com>gt;Meteorite-list at meteoritecentral.com
> >http://six.pairlist.net/mailman/listinfo/meteorite-list
>
>Prof. Zelimir Gabelica
>Universit? de Haute Alsace
>ENSCMu, Lab. GSEC,
>3, Rue A. Werner,
>F-68093 Mulhouse Cedex, France
>Tel: +33 (0)3 89 33 68 94
>Fax: +33 (0)3 89 33 68 15
>
><http://www.incredimail.com/index.asp?id=409&lang=9>IMSTP3.gif

Prof. Zelimir Gabelica
Universit? de Haute Alsace
ENSCMu, Lab. GSEC,
3, Rue A. Werner,
F-68093 Mulhouse Cedex, France
Tel: +33 (0)3 89 33 68 94
Fax: +33 (0)3 89 33 68 15
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Received on Sat 13 Jan 2007 11:57:36 AM PST