[Rockhounds] Need ID of Massive Moh 7.5 Crystal

[Axel Emmermann]

Is it absolutely sure that a #7 hardness pencil does NOT scratch the
surface?
Hold it perpendicular to the surface, apply enough pressure and, most
important, look at the scratch area with a loupe! Wipe any debris away with
your fingertip and look closely. I was fooled by the small size of a scratch
once too... 

Axel

> -----Oorspronkelijk bericht-----
> Van: rockhounds-bounces at lists.drizzle.com
[mailto:rockhounds-bounces at lists.drizzle.com]
> Namens GREGORY WEISBROD
> Verzonden: maandag 6 oktober 2008 4:58
> Aan: Rockhounds at drizzle.com: A mailing list for rock and gem collectors
> Onderwerp: RE: [Rockhounds] Need ID of Massive Moh 7.5 Crystal
> 
> The unusual hardness of your "glass" is interesting.  The general range of
5-6 being
> so greatly surpassed.  The hardness/toughness of surfaces is
problematical.  One
> variable might be the surface tension.  There is a neat illustration in
the tear shaped
> fast cooled "Prince Rupert's" drops or Dutch tears.  The rapid cooling of
the molten
> droplet sets up surface compression such that the bulbous part can be
struck with
> a hammer without effect.  The glass seems tougher or harder.  A second
possible
> factor could be in the surface solution of foreign ions.  The tin side of
float process
> plate glass is softer, whereas potassium ions substituted for the normal
sodium make
> the harder toughened glass.  Finally, the term glass can be generic.
There are a
> lot of metal silicate super cooled solutions possible, such as the lab
created Victoria
> Victoria stone of Dr. Imori as well as his facet material.  This stuff was
about 5.5
> hardness but certain ceramics are harder.  The natural world presents
obsidian and
> moldavite on the macro scale.
> 
> 
> 
> > Date: Sun, 5 Oct 2008 04:36:06 -0700> From: thai_buyer at yahoo.com> To:
> rockhounds at lists.drizzle.com> Subject: [Rockhounds] Need ID of Massive Moh
7.5 Crystal> >
> To all,> > I need the help of a serious rockhound. My travels have brought
this large
> crystalline rock into my hands. It weighs 2.15 kilos. It is a dark green,
that transitions to
> brown with yellow/gold crystal encrustations. The green section is
transparent / translucent
> while the darker composition is less so. Using a set of hardness pencils
(points) I have done a
> scratch test and all results show - 7 does not scratch and 8 does. Locale
of origin: Thailand /
> Cambodia. Based on the scratch test, it is obviously not quartz or glass.
My best guess at the
> moment is a variety of green Garnet, but I am not sure which variety.
Other less likely
> possibilities are beryl or tourmaline but neither comes from this area and
I don't think
> either one is found in a similar size. You may email me (Jim) at:
Thai_buyer at yahoo.com if you
> would like to discuss.  Picture attached.>  > Thanks,> > Jim> > > > > ---
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