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What is it #3
  
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Andrew Harvey




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PostPosted: Nov 22, 2017 14:02    Post subject: What is it #3  

Hi - the last question. This is another piece that I picked up in Cornwall. It could have been Cligga Head, it might have been The Lizard or between Porthleven and Loe Bar near Helston, or it could have been in a lorryload of gravel from a quarry on The Lizard.

It is jet black and highly lustrous on the three cleavage faces. It feels heavy for its size (31 gms) and it has a swirl at one end. My first thoughts were obsidian, but this is probably wishful thinking. I'd love to know what it is, as long as its not just coal or Liquorice!

Many thanks in advance



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Pete Richards
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PostPosted: Nov 22, 2017 14:22    Post subject: Re: What is it #3  

It would be helpful if you could convert your comments about relative weight into measures of specific gravity. You can see how here:
http://www.mineral-forum.com/message-board/viewtopic.php?p=38375#38375

My guess is that your first black material is coal, and your second is slag.

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Collecting and studying crystals with interesting habits, twinning, and epitaxy
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Pete Modreski
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PostPosted: Nov 22, 2017 17:28    Post subject: Re: What is it #3  

I agree with Pete; I think this one is a piece of slag--iron-rich glassy material left from some kind of a smelter. It appears to have air bubbles in it, and the swirly texture on the top surface are both typical of slag.
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Andrew Harvey




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PostPosted: Nov 23, 2017 14:43    Post subject: Re: What is it #3  

Oh well, thank you everyone for your help. Best wishes.
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