| P number: | P524374 |
|---|---|
| Caption: | Photomicrograph of Dunsapie basalt. Light: XPL, Magnification x 2. Arthur's Seat, Edinburgh, Lothian Region. |
| Description: | The image is a photomicrograph of a thin section, taken in crossed-polarized light, of basalt from Arthur's Seat in Edinburgh. The different birefringence colours of the constituents allow the different mineral types to be distinguished. British Geological Survey Petrology Collection sample number S 12562. Light: XPL, Magnification x 2. Light: XPL, Magnification x 2. The brightly-coloured minerals are phenocrysts of olivine and pyroxene. The fine-grained groundmass contains abundant randomly oriented laths of plagioclase feldspar which has a variable grey birefringence. Carboniferous basalt lavas are classified into six types. Dunsapie-type basalt is one of these types. This classification is used extensively in the Midland Valley and is easily applied to field mapping. Dunsapie-type basalts have phenocrysts greater than 2mm i.e. they are macroporphyritic, the phenocrysts are of plagioclase olivine and clinopyroxene. The type locality is Dunsapie Hill, Edinburgh, a vent intrusion. |
| Date taken: | Wed Jan 01 00:00:00 GMT 2003 |
| Photographer: | Hyslop, E.K. |
| Copyright statement: | NERC |
| Orientation: | Landscape |
| Size: | 367.13 KB; 1000 x 672 pixels; 85 x 57 mm (print at 300 DPI); 265 x 178 mm (screen at 96 DPI); |
| Average Rating: | Not yet rated |
| Categories: | Best of BGS Images/ Rocks and minerals under the microscope |
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