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P521281


P number: P521281
Caption: Rock specimen of augen gneiss. Meall Gruiam, Kincraigie, Glen Tilt, 2 miles north of Blair Atholl, Perthshire, Scotland.
Description: The sample is a coarse-grained gneiss with a 'granitic' texture, comprising orange-red feldspar, grey quartz and dark mica. It probably represents a rock formed as a result of partial melting under high grade metamorphic conditions. This has allowed large feldspar crystals to grow which dominate the rock. British Geological Survey Petrology Collection sample number EMC1644. Augen is the German word for 'eyes' and refers in geology to clots of coarse-grained crystals which have an ellipsoidal shape. They occur in metamorphic rock, typically gneisses. The geology of Glen Tilt is complicated by the presence of an important dislocation or ductile fault feature called the Boundary Slide. It forms a zone of deformed and platy rocks varying from 500 to 2000 metres thick, and extends from Glen Tilt to Dalmally. The rock is Dalradian (Precambrian) age.
Date taken: 01/12/2002
Photographer: McTaggart, F.I.
Associate: T.S. Bain
Copyright statement: NERC
Additional information: EMC1644
Orientation: Landscape
Size: 277.23KB; 1000 x 775 pixels; 85 x 66 mm (print at 300 DPI); 265 x 205 mm (screen at 96 DPI);
Average Rating: Not yet rated
Categories: Best of BGS Images/ Geological structures  

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