St. Austell Granite from Gready Quarry. 1914.

Crystals of orthoclase with inclusions of biotite

 Crystals of orthoclase with inclusions of biotite

Twinned crystal of orthoclase

 Quartz-tourmaline rock or 'stent'

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

Posted by Bob McIntosh

Pigs Eggs - Kaolinized Crystals of Orthoclase. Cleaves Pit, Caudledown, Cornwall.

BGS image ID: P804217

'Pigs Eggs' Kaolinized Crystals of Orthoclase. Cleaves Pit, Caudledown, Cornwall. Geologists' Association North Cornwall Field Excursion April 16th 1914.

Today, there is a Pig's Eggs Trail

From the Geologists' Association Carreck Archive.

Bob McIntosh