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FORTHCOMING EVENTS

   

The 'Virtual'

Festival of Geology 2020

Saturday 7th and Sunday 8th November 2020

Save the dates!​​​​​​​

  

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PITCHSTONE

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Home > MINERALS > UNUSUAL ROCKS AND MINERALS - WEIRD AND WONDERFUL !

 
PITCHSTONE
 
Like obsidian, pitchstone is a natural volcanic glass, formed when lava from a volcano cools extremely quickly leaving no time for crystals to grow.  It is the same chemical composition as granite but granite has cooled very slowly deep underground forming large crystals.  
  
Pitchstone has a higher water content than obsidian and has a jagged or ‘hackly’ fracture rather than the characteristic conchoidal fracture of obsidian.
  
This is a very good example showing some flow banding. It is from an old collection with no provenance.
  
Click on a picture for a larger image


Size:  6.5 x 6 x 5 centimetres
Weight:  272 grams

PRICE: £12.00
Sorry, this item has been sold or is out of stock