| P number: | P521237 |
|---|---|
| Caption: | Rock specimen of porphyry. Canisp mountain, Assynt, Sutherland, Scotland. |
| Description: | The sample is a distinctive red-coloured crystalline igneous rock with large pale and pinkish feldspar crystals set within a stronger reddish fine-grained groundmass. The feldspars are of two shapes; elongate laths and large equant subspherical grains. Porphyrites are well known as attractive rocks, and have long been used as decorative building stones. British Geological Survey Petrology Collection sample number EMC376. Porphyry is a textural term used to describe an igneous rock which contains conspicuous large crystals or 'phenocrysts' within a fine-grained groundmass. The term comes from a Greek word for purple, and was first applied to a purple-red-coloured rock from Egypt. Canisp porphyry are regarded as part of the Younger Caledonian igneous suite of rocks and on the whole, they have not suffered the major metamorphic recrystallization found in older Caledonian igneous rocks. The Canisp porphyry are restricted in distribution to the undisturbed 'Foreland' of the Moine Thrust Zone and it is thought that they were emplaced after the movement of the Moine Thrust and is related to the Loch Borralan Complex which has been dated at c. 430 Ma (Silurian in age.) |
| Date taken: | Sun Dec 01 00:00:00 GMT 2002 |
| Photographer: | McTaggart, F.I. |
| Associate: | T.S. Bain |
| Copyright statement: | NERC |
| Additional information: | EMC376 |
| Orientation: | Landscape |
| Size: | 264.08 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: | Unsorted Images |
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