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The 'Virtual'

Festival of Geology 2020

Saturday 7th and Sunday 8th November 2020

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PIG'S EGGS - PSEUDOMORPHS OF KAOLINITE AFTER FELDSPAR - Cornwall

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

  

PIG'S EGGS

Pseudomorphs of kaolinite after feldspar

St. Austell, Cornwall
 

Kaolinite is a clay mineral and rocks that are rich in kaolinite are known as kaolin. Kaolin, or china clay, is an essential ingredient in the production of china and porcelain and also used in the manufacture of paper, and other products.

  

Kaolinite is formed from the decomposition of feldspar crystals and in the china clay pits of Cornwall the decomposing feldspar comes from granite. Feldspar crystals are replaced by kaolinite molecule by molecule, taking on the shape of the original crystal. The resulting crystal is called a ‘pseudomorph’ (literally ‘false form’).

  

Such crystals have been called ‘pig's eggs’ by the quarry workers. 

 

These examples are from an old collection. They are presented in a glass-topped display box.
  
Please note: the crystals may move during transport.

Click on a picture for a larger image


Size:  5 x 5 x 2 centimetres (size of box)
Weight:  38 grams

PRICE: £25.00