| P number: | P521306 |
|---|---|
| Caption: | Rock specimen of granulitic gneiss. South slopes, Craig of Tulloch, Rinloan, Glen Gairn, Aberdeenshire, Scotland. |
| Description: | The sample is a banded gneiss with a striped appearance defined by compositional layers of varying colours due to differing proportions of feldspar, quartz and darker mafic minerals. British Geological Survey Petrology Collection sample number EMC1147. A gneiss is a high grade metamorphic rock with a banded texture consisting of generally regular layers typically of alternating schistose bands of mafic minerals such as micas or amphibole, with siliceous bands chiefly made up of quartz and feldspar (quartzo-feldspathic bands). Gneisses are generally coarse-grained rocks which have undergone substantial recrystallization. The term granulitic was once commonly used to describe coarse-grained, crystalline metamorphic rocks with a granoblastic texture. However the term has also been widely used for igneous and sedimentary rock as well, often with different meanings. It is a term that should nowadays only be used when precisely defined. The rock will be Precambrian 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: | EMC1147 |
| Orientation: | Landscape |
| Size: | 259.51 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/ Geological structures |
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