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Uploaded on:
2009-03-17 20:19:54.0
Type:
Digital Asset
File Size:
151.78 KB
Dimensions:
1000 x 775 pixels
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P number: P519712
Caption: Specimen of metamorphosed dolerite from Kilmartin Quarry, Argyllshire, Scotland
Description: The sample is a cut and polished slab of metamorphosed dolerite which has been used as a decorative building stone. The specimen is of Precambrian, Dalradian age. British Geological Survey Petrology Collection sample number EMC 5692. The sample has a fine-grained, dark green appearance. Metamorphosed basic igneous rocks are commonly referred to as Metabasic rocks. They generally have a mineral composition that is dominated by the products of metamorphic reactions, and may contain no remnants of their primary igneous mineral assemblage. Most metabasic rocks contain plagioclase feldspar. The particular species and composition of the plagioclase generally depend on the pressure and temperature conditions of the metamorphism. At the lowest grades the dominant feldspar is albite. As the grade increases the plagioclase becomes more calcium-rich.
Date taken: Wed Jan 01 00:00:00 GMT 2003
Photographer: Bain, T.S.
Copyright statement: NERC
Orientation: Landscape
Size: 151.78 KB; 1000 x 775 pixels; 85 x 66 mm (print at 300 DPI); 265 x 205 mm (screen at 96 DPI);
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