[meteorite-list] Fake Moldavites

[Zelimir Gabelica]

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 <info at meteoritenhaus.de> 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