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Uploaded on:
11/03/2009 05:34:32
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138.25 KB
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P number: P521519
Caption: Mineral specimen of quartz amygdale. Dunure Railway, Brown Carrick Hills, Ayrshire.
Description: The sample is a quartz amygdale, with 'drusy' quartz of amethystine (violet) and smoky (brown) varieties. British Geological Survey Petrology Collection sample number E 3309A. The term drusy is used to describe an irregular cavity or opening in a vein or rock, where the interior walls are encrusted with small projecting crystals. They are sometimes also known as miarolitic cavities. The specimen is from the Lower Old Red Sandstone (Devonian) Maybole Volcanic Series, Dunure Railway, Brown Carrick Hills, Ayrshire. The majority of lava flows are composed of olivine-basalt containing abundant feldspar phenocrysts. The lavas are generally thin, usually 10-15 feet thick and are clearly distinguished from each other by the slaggy tops and bases. The lavas contain vesicles that are usually infilled to form amygdales with one or more of the following minerals: quartz, agate or chalcedony.
Date taken: 01/01/2003
Photographer: Unknown
Copyright statement: NERC
Orientation: Landscape
Size: 138.25 KB; 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/ Rocks and minerals  


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