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What is it? Chalcedony?
  
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BHmineral




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PostPosted: Jan 25, 2017 10:38    Post subject: What is it? Chalcedony?  

Hi,

What is it? Chalcedony in coral? It is from Tampa Bay, Florida - USA

Size: 6 x 4,5 cm

Thank you.



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James
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PostPosted: Jan 25, 2017 10:48    Post subject: Re: What is it? Chalcedony?  

Could you please do a hardness test?

http://www.mineral-forum.com/message-board/viewtopic.php?p=19487#19487

If it is chalcedony it should scratch glass

James
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kushmeja




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PostPosted: Jan 25, 2017 10:50    Post subject: Re: What is it? Chalcedony?  

Yes - this is fossilized coral that was replaced by quartz/chalcedony. It looks similar to the the material from the Tampa Bay area, but could possibly be from another area of FL or southern GA.
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Bob Carnein




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PostPosted: Jan 25, 2017 10:51    Post subject: Re: What is it? Chalcedony?  

It is chalcedony. These "geodes" often fill or replace fossil corals from the Oligocene (?) Hawthorn Group, on Tampa Bay.
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Bob Harman




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PostPosted: Jan 25, 2017 11:20    Post subject: Re: What is it? Chalcedony?  

This is a long time well recognized deposit of fossilized coral replaced by quartz var chalcedony. They are from Tampa Bay, Florida as this one is. In my opinion, no testing is necessary on classic pieces as this one is. BOB
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markbeckett




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PostPosted: Jan 25, 2017 13:38    Post subject: Re: What is it? Chalcedony?  

How Amazing!
_________________
Ex Camborne School of Mines
Grad - B.Eng. Geol. (1993)

'if you see a strange hill, go and prospect there'...(KFG Hosking)
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