| P number: | P524356 |
|---|---|
| Caption: | Photomicrograph of amphibolite. Light: XPL, Magnification x 2. Strathmashie, Highland. |
| Description: | The image is a photomicrograph of a thin section of amphibolite rock, taken under crossed-polarized light in order to show the interference colours of the constituent minerals. The brightly coloured grains are amphiboles, whilst the grey coloured crystals are plagioclase feldspar. British Geological Survey Petrology Collection sample number N 1592. Light: XPL, Magnification x 2. Light: XPL, Magnification x 2. Plagioclase feldspar can often be identified in thin section by the presence of lamellar twinning, such as in several of the grains in the image. The twinning is visible under crossed polarised light as a series of parallel bands, each having a different shade of grey colour. Other types of feldspar have different twinning styles, such as microcline which has a distinctive cross-hatch or 'tartan' pattern of twinning. An amphibolite is a crystalloblastic rock consisting mainly of amphibole and plagioclase with little or no quartz. As the content of quartz increases, the rock grades into hornblende plagioclase gneiss. The term amphibolite was originated by Brongniart. |
| Date taken: | Wed Jan 01 00:00:00 GMT 2003 |
| Photographer: | Hyslop, E.K. |
| Copyright statement: | NERC |
| X longitude/easting: | 258450 |
| Y latitude/northing: | 791200 |
| Coordinate reference system, ESPG code: | 27700 (OSGB 1936 / British National Grid) |
| Orientation: | Landscape |
| Size: | 265.21 KB; 1001 x 670 pixels; 85 x 57 mm (print at 300 DPI); 265 x 177 mm (screen at 96 DPI); |
| Average Rating: | |
| Categories: | Unsorted Images |
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Reviews
Aidan Karley - 24/11/2010
Second order brilliance!
I always loved amphiboles under XPL when I was a student. I even "wasted" one of my handfull of sections for my honours thesis on sectioning an amphibolitite nodule from the Lewisian on Mullach Choire Mhic Fhearchair, and wasn't disappointed. I graduated in a tie whose designer must have seen an amphibolitite under XPL. Those days are gone ; the tie went through the boil wash then into the bin ; my petrological microscope left home with the burglars. But the Lewisian is still there. And I've got a new, eye-wateringly bright desktop wallpaper in the middle of a snowy North Sea.