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Very Hot Topic (More than 25 Replies) Pop-Pop Point, NC (Read 25283 times)
JoeM
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Re: Pop-Pop Point, NC
Reply #60 - Nov 8th, 2014 at 6:35pm
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Thanks for keeping everyone up-to-date on what you have been finding out, Robert.

It is interesting, that when all is said and done, there is no
consistent "standard" for when a green beryl deserves to be called an Emerald.
No exact chemical signature or coloring mineral to go by.
As you say, Tis' in the eye of the beholder.

There is a difference in quality between the two beryls you found.
Unfortunately, the gemmier one is a poor specimen to cut.
The larger one could be cut, but is opaque quality.
I still think they both qualify as emerald, but if you want to call one green beryl,
then you got one of each! Cool
  
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Ezdiggin
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Re: Pop-Pop Point, NC
Reply #61 - Nov 8th, 2014 at 11:59pm
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It all depends on the chromium and vanadium presence.  Only chromium is an emerald, chromium and less vanadium is emerald.  Only vanadium is considered by some as emerald and some as not emerald.  No chromium or vanadium is not emerald, usually colored by iron.  This may have been stated before, but it's what is widely regarded as the standard from my experience. Color means absolutely nothing if the chromophore is iron.
  
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Dennis
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Re: Pop-Pop Point, NC
Reply #62 - Nov 9th, 2014 at 9:35am
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Also, to help stir the muddy water regarding emeralds vs. green beryl:

Emerald is a recognized variety of Beryl by the gemological community (Gemologists), not the mineralogical community (i.e. IMA).   Gemologists make the determination as to what makes an Emerald an Emerald (chromium vs. Vanadium vs. iron) as Ezdiggin said.

The same goes for any colored variety of any mineral species, i.e. Corundum (var. Ruby & var. Sapphire), other Beryls (var. Aquamarine, var. Heliodor, var. Morganite, and var. Goshenite), and on and on.

The IMA sets the standards for mineral species and approves the names for them.  If Beryl had enough chromium in the empirical formula, then they might name it Beryl-Cr (=Emerald), but they don't currently.

I like to use the varietal names because it basically describes a specimen to its color, but I have many common beryls in my collection that I have collected.  I refer to my specimens as yellow beryl, yellow-green beryl, blue beryl, etc.

Dennis
  
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L82Play
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Re: Pop-Pop Point, NC
Reply #63 - Nov 12th, 2014 at 3:07pm
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Hi,

Thanks for the info.

I guess gemologist are artist while mineralogist are scientist and those two groups very seldom agree on much.  I'm with Ezdiggin - if it has chromium in it - it's emerald.  And I'm OK with having one of each, Joe.

This link will open a PDF file regarding Egyptian emeralds and green beryl.  Article starts on page 100 (page 25 in PDF).

On page 111, GIA distinguished green beryl from emerald by their color:

'Because Egyptian stones are described as often being light toned, the question has arisen as to whether they are properly classified as emeralds rather than green beryls. The staff of the GIA Gem Trade Laboratory determined that, on the basis of color, 12 of the 14 specimens used in the gemological study were appropriately called emerald, while the other two qualified as green beryl.'


Page 112 gets interesting in the section: 'GEMOLOGICAL AND SPECTROSCOPIC CHARACTERISTICS' - where they covered the testing they performed.  A lot of this wording could just as well be describing my Mine Creek emeralds.

http://www.gia.edu/cs/Satellite?blobcol=gfile&blobheader=application%2Fpdf&blobh...

If the link doesn't work - use Google to search for : G&G Summer 1993 "Emerald Matrix" from North Carolina or Egypt for ancient stones (G&G Summer 1993 "Emeralds and Green Beryls of Upper Egypt.

cheers,
r
  
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JoeM
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Re: Pop-Pop Point, NC
Reply #64 - Nov 12th, 2014 at 11:00pm
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Very interesting article, Robert. An enjoyable read on the subject of emeralds.
I have never read anything from that publication before but
will have to try and check it out more.
And the picture of the oxidized amphibole "stalks", Figure 19, page 114,
was nice to see.
The article does reference some other good sources of information to be checked out.
Good job. Thanks for the link.
  
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L82Play
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Re: Pop-Pop Point, NC
Reply #65 - Nov 13th, 2014 at 3:16pm
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Hi,

I looked at that page too and wondered if you cut and polished the smaller emerald and magnified it 25X if those impurities Professor Fodor saw are actually stalks!!!  Maybe not a star trapiche - but stalks would be cool too!

cheers,
r
  
sung to the tune of 'Green Acres'
Erosion is the thing for me
I just don't like to dig - you see
Picking rocks up right off the ground
is good enough for this lucky old rockhound
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L82Play
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Re: Pop-Pop Point, NC
Reply #66 - Dec 10th, 2014 at 6:38pm
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Hi,

Interesting refractive index table showing that you may be able to distingush an emerald's origin by it's refractive index.

http://gemologyonline.com/csi.html

Now I'll have to find someone with a refractometer.  Any volunteers?

cheers,
r
  
sung to the tune of 'Green Acres'
Erosion is the thing for me
I just don't like to dig - you see
Picking rocks up right off the ground
is good enough for this lucky old rockhound
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Tim4d
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Re: Pop-Pop Point, NC
Reply #67 - Dec 11th, 2014 at 11:30am
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I'll keep an eye out for one of these at flea markets and garage sales!
  
Gemref604.jpg ( 29 KB | 94 Downloads )
Gemref604.jpg
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