[Rockhounds] Need ID of Massive Moh 7.5 Crystal

[Tim Jokela Jr.]

Wellll..... it's hard to judge from a single pic, but at the risk of looking 
foolish, as I'm no gem expert, here's my mental process upon seeing the 
photo:

It's not a crystal or a crystalline rock, it's a mass. No rounded edges, so 
can't be from an alluvial deposit as one might expect in that part of the 
world. And hence can't be a tektite/moldavite. No apparent crystal faces, so 
no hints to ID there, though that lack is certainly a clue - a piece that 
big with no xl faces... hmmm. Absurd size for a garnet, rather excessive for 
a tourmaline, (would be kilobucks for a piece of tourmaline carving rough 
that size) not terribly large for a beryl, but the color is very wrong for 
beryl. Size also very wrong for say forsterite ("peridot"), or diopside, 
zircon, pargasite and other green rarities; what other green minerals can I 
think of... fluorite would show cleavage. Not a whole lot of green minerals 
found in 5" gemmy chunks you see. Shaky provenance, no locality info... 
great whopping hunks of gem material like that seldom fall into tourists 
hands; the path from miner to buyer then cutter is well beaten.

Taking into consideration the size, color, color zoning, bubbles, perhaps 
some hints of conchoidal fracture, no real obvious cleavage, no apparent 
matrix or crystal faces... looks a lot like glass to me. Glass can have 
variable hardness so that's not really hard evidence against.

A hands-on examination would confirm it quickly. Take it to a local jewelry 
shop with a good gemologist, or a local gem & mineral club, or a 
university/museum's geology/mineralogy department, and see what they say.

Given the above, I sure hope you didn't pay much for this. If you did; let's 
hope I'm proven wrong by the gem folks on the list!

Cheers,

T


----- Original Message ----- 
From: "Jim Marshall" <thai_buyer at yahoo.com>
To: <rockhounds at lists.drizzle.com>
Sent: Sunday, October 05, 2008 10:40 AM
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 link below:

http://smg.photobucket.com/albums/v177/thai_buyer/?action=view&current=IMG_0687.jpg

Thanks,

Jim





--- StripMime Report -- processed MIME parts ---
multipart/alternative
  text/plain (text body -- kept)
  text/html
---
-- 
_______________________________________________
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