Just for the fun, I can analyze the fakes, for major and trace elements.
Jean-Alix Barrat
Professor of Geochemistry
UBO-IUEM
CNRS, UMR 6538 ("Domaines Océaniques")
Place Nicolas Copernic
29280 Plouzané Cedex
Zelimir Gabelica a écrit :
Mike, Bernd, Andi, Michael, all,
Could be interesting to perform some accurate chemical analysis on
some selected fakes.
Probably the relative amounts of main oxides (SiO2 from 79 to 83%,
Al2O3 from 8 to 11%, K2O from 2.4 to 3.4%, CaO from 1.4 to 2.7%, or
MgO from 1.3 to 1.9%, as taken from data given by Heinen, after Bouska
(1994) for 3 main moldavite deposits - see his book "Tektites,
witnesses of cosmic catastrophes, p 89) would be similar.
But how about minor oxides (TiO2, MnO or Na2O) ? Not to speak about
the REE (rare earth elements) that are present in the ppm (part per
million) range in natural moldavites.
Could the "fakers" have thought to add in right proportions all these
REE in right proportion ?
Sure, such an analysis is not easy to perform and is certainly
expensive and basically nobody among the buyers would have even
thought to do it on their purchased pieces.
But I would just be curious about the bulk composition of the fakes.
Indeed it can be possible that some very different chemical
composition would also yield such a "nice"" green shade, while this
green color is probably attanied to in real moldavites because of the
presence of some minor impurities.
Did someone try to analyze the fakes ?
This being, I agree with Michael, this is a real tragedy for
collectors as there is probably nothing more to do than to carefully
look for external characteristics (bubbles, "schlieren"...) on a
suspected moldavite and further check the purchase date and the
dealer's name for our older collection pieces.
Good luck and thanks Mike and Michael for their warnings.
Anyway....Merry Christmas to everybody and many happy huntings for the
New Year to come!
Zelimir
A 14:16 20/12/2007 -0800, Michael Farmer a écrit :
Yes, these fake Chinese pieces are perfect, with great
color and no flaws. That lack of flaws should be the
first indication of authenticity.
They are melting glass and pouring molds.
Michael Farmer
--- Andreas Gren <[EMAIL PROTECTED]> wrote:
> Not to forget, the small bubbles in the real
> Moldavites and the "Schlieren"
> in the real Moldavites, like the Schlierenbands in
> some Ataxites
>
> Bubbles: http://moldavit.de/foto/fsammlung3.htm
>
> Schlieren: http://moldavit.de/foto/fsammlung2.htm
>
> Best regards
> Andi
>
>
> Mike wrote:
>
> They were mostly set in wire as pendants, and when
> put side by side, you
> could clearly
> see them as identical, made in a mold. I have found
> one of the same on ebay,
> at a very
> high price.
>
>
http://cgi.ebay.com/Czech-Moldavite-200-5-Carat-Green-Meteorite-Tektite_
>
W0QQitemZ200179801535QQihZ010QQcategoryZ3239QQssPageNameZWDVWQQrdZ1QQcmdZVie
> wItem
>
> You can clearly recognize this one is an artifact (a
> fake) because the
> greenish
> color is way too "monotonous" and the grooves too
> "regular" !!!
>
> Bernd
>
Prof. Zelimir Gabelica
Université 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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