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Glass or something else?
  
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Diamond




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PostPosted: Jul 02, 2018 10:19    Post subject: Glass or something else?  

Hello! Beginner I am bit I used to collect minerals and fossils as a kid a very long time ago.
Anyway to the point: what is this? It has kind of Snowflake crystals in layers inside and some on the outside and no bubbles spotted yet possibly obsidian but maybe glass etc. I guess. Bought in an auction with lots of other bits I'll be posting later :) ... Thanks!



20180702_161230.jpg
 Mineral: Glass or obsidian maybe.
 Description:
Sussex
16 cm X 8 cm roughly
Fairly thin one end thickening up to 5cm ish at the other.
 Viewed:  1057 Time(s)

20180702_161230.jpg


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Diamond




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PostPosted: Jul 02, 2018 10:21    Post subject: Re: Glass or something else?  

A bigger photo:


20180702_145709.jpg
 Description:
 Viewed:  1054 Time(s)

20180702_145709.jpg



20180701_151422.jpg
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 Viewed:  1054 Time(s)

20180701_151422.jpg


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lluis




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PostPosted: Jul 02, 2018 10:31    Post subject: Re: Glass or something else?  

To my eyes, glass...

With best wishes

Lluís
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vic rzonca




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PostPosted: Jul 02, 2018 10:35    Post subject: Re: Glass or something else?  

Not something else.
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James
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PostPosted: Jul 02, 2018 10:59    Post subject: Re: Glass or something else?  

Glass. I collected huge amounts of obsidian as a child (in Mexico) and this is glass.
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Pete Modreski
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PostPosted: Jul 02, 2018 11:41    Post subject: Re: Glass or something else?  

Yes, glass. The "snowflakes" can form when the molten glass is cooled slowly enough to allow that to happen; either accidentally, or on purpose to make an attractive pattern within the glass that will be sold for decorative purposes.
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Diamond




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PostPosted: Jul 02, 2018 14:11    Post subject: Re: Glass or something else?  

James wrote:
Glass. I collected huge amounts of obsidian as a child (in Mexico) and this is glass.

Ah ok was that the green type I hear Mexico has?
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Diamond




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PostPosted: Jul 02, 2018 14:18    Post subject: Re: Glass or something else?  

Pete Modreski wrote:
Yes, glass. The "snowflakes" can form when the molten glass is cooled slowly enough to allow that to happen; either accidentally, or on purpose to make an attractive pattern within the glass that will be sold for decorative purposes.

Ah ok any more info on that? Sounds interesting.

I've just realised I had a stone called an Indian tear drop a long time ago I'm guessing it may of been a black obsidian rock or another fake... I'll look for it :) ...
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Diamond




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PostPosted: Jul 03, 2018 06:38    Post subject: Re: Glass or something else?  

Ah I can see more clearly now with your help. I wonder if there actually is any very clear volcanic glass like this. Some people seem to think there are rare occurrences and other say it's a different process that makes items a bit like this.

There was one link to an interesting thing and that was the Eifel volcanic area of Germany apparently has clear blue and sometimes green glass minerals : (I tried putting a link here to some examples but it won't let me) I guess you may know of it it can Google it sorry thanks.
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Justin Hickok




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PostPosted: Jul 20, 2018 11:59    Post subject: Re: Glass or something else?  

It pretty, none the less.
I once worked at a light bulb factory in Salina Kansas called Philips Lighting, and I worked all over the plant but I had to work the glass plant once in a while and I would collect glass blobs that spilled over. It was a beautiful aqua color but I soon learned the hard way that it wasn't a good idea because one night we were watching a movie and one of them about the size of a football exploded. I heard this faint pop sound and a few seconds later kaboom!
It blew my display case in pieces. Luckily we weren't injured but it was a heck of a mess to clean up. I had to replace the carpet.
So be careful with glass because it's under pressure. Like a ticking time bomb.
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vic rzonca




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PostPosted: Jul 20, 2018 16:14    Post subject: Re: Glass or something else?  

Not annealed properly or at all. Glass that has not been properly annealed retains thermal stresses caused by quenching, which indefinitely decrease the strength and reliability of the product. Inadequately annealed glass is likely to crack or shatter when subjected to relatively small temperature changes or to mechanical shock or stress. Annealing is slow, controlled cooling. Damn, in your case no less.
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Justin Hickok




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PostPosted: Jul 21, 2018 00:19    Post subject: Re: Glass or something else?  

Thanks for the explanation. It's like tempering maybe?
Or comparable to hardening metals / steel?
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James
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PostPosted: Jul 21, 2018 14:56    Post subject: Re: Glass or something else?  

A a child I found black obsidian in Mexico. A new road cut through an area with lots of obsidian so the largest block I found was about 30cm - my parents left it behind when we moved so someone must still have it in their garden. I also collected hundreds of obsidian blades and some of them (well one or two) were/are totally clear. The best I had was stolen when we moved house - 10cm long and totally transparent

Diamond wrote:
Ah I can see more clearly now with your help. I wonder if there actually is any very clear volcanic glass like this. Some people seem to think there are rare occurrences and other say it's a different process that makes items a bit like this.

There was one link to an interesting thing and that was the Eifel volcanic area of Germany apparently has clear blue and sometimes green glass minerals : (I tried putting a link here to some examples but it won't let me) I guess you may know of it it can Google it sorry thanks.
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Diamond




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PostPosted: Jul 22, 2018 16:10    Post subject: Re: Glass or something else?  

Ah ok. Well I might cut this with diamond bits as it's glass just so you can see light through it better as it's pretty thick possibly turn it into a display piece for fun. And yes looks nice :) .
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