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 Post subject: Re: How to separate Manmade Glass vs Obdisian vs Moldavite
PostPosted: Thu Jan 30, 2014 11:43 pm 
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Joined: Tue Oct 17, 2006 11:33 am
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Location: New Zealand
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A blue volcanic glass ? In the Alps ??? :roll:


Yes there is some blue volcanic glass that is found around 2km away where the Hauyn is found in Mendig Germany(not the Alps) , if you think Hauyn is rare try to find that blue glass :mrgreen: I have seen 2 pieces while being for 7years in Germany and looking for some. There was a article in the German Lapis magazin a few years ago.
But be aware we had last year at a trade show in Switzerland some one trying to sell some" blue volcanic glass ".
I made the call to the organizer and the material got removed from the show.
So reality is you much likely never see that blue volcanic glass in the trade beforits even found the collectors are lined up to buy it :D

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 Post subject: Re: How to separate Manmade Glass vs Obdisian vs Moldavite
PostPosted: Wed Sep 17, 2014 12:14 pm 
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OK, I was in Oregon this year by Glass Butte to collect obsidian, and we stopped into a local rock store. And what do you know, they had some of the elusive blue obsidian! It's real! But not what we were thinking of!
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First: it's almost opaque (slight translucency on the edges)
second: it's a bit less blue in person at the best of times, and it varies a lot with light (sometimes more grey, sometimes more green).
Oddly it isn't a sheen obsidian or anything like that, just a very milky obsidian with a black crust and a bluish core. We also found a green example in the field on Glass Butte itself.

Anyway, it's interesting, and not inaccurate to call it blue or green, but it's a very far cry from the green bottle glass we've all seen before.

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 Post subject: Re: How to separate Manmade Glass vs Obdisian vs Moldavite
PostPosted: Wed Sep 17, 2014 1:39 pm 
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Sorry missed your initial info.
It is hard with any certainity to differentiate with ordinary gemological instruments. One has to use the tables over different RI:s and SG for know samples and also compare the appearance.

With a raman unit I have seen all my natural moldavites are very similar in their spectrum and different from man mad glass. Nothing conclusive though.

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 Post subject: Re: How to separate Manmade Glass vs Obdisian vs Moldavite
PostPosted: Tue Dec 01, 2015 5:29 am 
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iwakasu wrote:
Since that three igneous rock species could overlap in visual and physical characteristics, then how can we separate them? Thanks.......



Moldavite molten glass is not homogeneous as it contains inclusions (impurities). Inspection the inner structure is the most reliable indicator.
Counterfeits made of glass are very homogeneous and do not, in most cases, contain impurities.

Moldavites contain lechetelierite (impurity) – neither volcanic glass (obsidians) do. The enamel of obsidians is paralelly wrinkled. Moldavites have a fluid structure oriented in several possible ways.


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