[Rockhounds] Need ID of Massive Moh 7.5 Crystal

[GREGORY WEISBROD]

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> > > > > --- StripMime Report -- processed MIME parts ---> multipart/mixed> multipart/alternative> text/plain (text body -- kept)> text/html> image/pjpeg> ---> -- > _______________________________________________> Rockhounds at drizzle Mailing List> Subscription Services:> http://lists.drizzle.com/mailman/listinfo/rockhounds> List Home Page, with a link to the List Usage Policy:> http://www.eclecticlapidary.com/Rockhounds/index.html

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