Sunday, 9 February 2014

St. Austell Granite from Gready Quarry. 1914.

Crystals of orthoclase with inclusions of biotite
Crystals of orthoclase with inclusions of biotite


Crystals of orthoclase with inclusions of biotite
 Crystals of orthoclase with inclusions of biotite


Twinned crystal of orthoclase
Twinned crystal of orthoclase


 Quartz-tourmaline rock or 'stent'
 Quartz-tourmaline rock or 'stent'


Photographs are from the Geologists' Association 'Carreck Archive' held at the British Geological Survey.



Posted by Bob McIntosh

No comments:

Post a comment