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EXPLOSION BRECCIA - St. Austell, Cornwall

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EXPLOSION BRECCIA

Evidence of a violent, high pressure shattering of rock

St Austell, Cornwall

The breccia from Wheal Remfry, near St. Austell in Cornwall is one of Britain's most unusual rocks.  It is thought to originate from hot, molten rock under great pressure deep underground. 
  
A sudden release of that pressure - possibly by the molten rock reaching the surface - led to explosive decompression, causing the adjacent rocks to shatter and the mass of hot fluid and rock fragments to surge upwards, rather like champagne being released from a bottle when the cork is removed.  This event occurred about 270 million years ago. 

The fragments are granite and other rocks from great depth. As the pressure fell, the black mineral tourmaline crystallised around the rock debris.  Breccia is the name given to a rock containing fragments cemented together, but few other breccias have been formed in such a dramatic way.

Wheal Remfry is a former china clay pit. This specimen was collected in the 1990s during roadworks for the A30 trunk road. 

Click on a picture for a larger image

Size: 10 x 8 x 7 centimetres
Weight: 647 grams

PRICE: £26.00
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EXPLOSION BRECCIA  -  St. Austell, Cornwall
EXPLOSION BRECCIA  -  St. Austell, Cornwall EXPLOSION BRECCIA  -  St. Austell, Cornwall EXPLOSION BRECCIA  -  St. Austell, Cornwall EXPLOSION BRECCIA  -  St. Austell, Cornwall