Altered tourmaline granite - St Austell
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Fact sheet
Description: 

This altered granite comes from a location within Littlejohn's china clay pit, St Austell, Cornwall. China clay in this area was created while the molten granite was still cooling, when it was fluxed by fluids rich in water, boron and fluorine, attaching the sodium-rich feldspar. Clay is mined in this area by high pressure water hoses and filtering to remove the remaining micas and quartz. Littlejohn's pit has been active since the 1800s and continues to supply fine clays suitable for use in paper making.

In thin section the rock contains altered feldspars and quartz. Small grains of tourmaline and altered biotite with many pleochroic haloes are also present.

In Place
In Time
infoImage: 
Location description: 
Littlejohn's china clay pit, St Austell, Cornwall
Accuracy:
Location precision: 
Good
Timescale:
Timescale: 
Permian
Ma = Millions of years ago
In Focus
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Type:
Type: 
igneous
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