| P number: | P524303 |
|---|---|
| Caption: | Photomicrograph of peridotite. Light: XPL, Magnification x 2. North-north-west of Hallival, Rum, Invernessshire. |
| Description: | The image is a photomicrograph of a thin section of an ultramafic rock from Rum, showing abundant small grains of opaque chromite amongst larger interlocking crystals of plagioclase feldspar. The image is taken under cross-polarized light in order to show the lamellar twinning in the plagioclase. British Geological Survey Petrology Collection sample number S 96998. Light: XPL, Magnification x 2. Light: XPL, Magnification x 2. Feldspar is normally absent from ultramafic rocks such as peridotites. However in some instances it can occur, such as the well known contact zone between leuconorite and chromitite in the Bushveld Complex of the South African Transvaal. Here the chromite crystals have settled through the molten magmas but have become trapped by the crystallization of silicate minerals, namely plagioclase feldspar. Had the magma remained fluid for a longer time these minerals would have been segregated (as in normal ultramafic rocks). The Rum Tertiary central intrusion complex developed in two stages, the first was dominated by intrusive and extrusive acid magmatism and ring faulting and the second was the intrusion of mafic magmas which gave rise to the layered ultrabasic complex for which Rum is famous. The complex was intruded into the surrounding Torridonian (Precambrian) rocks. |
| Date taken: | 01/01/2003 |
| Photographer: | Hyslop, E.K. |
| Copyright statement: | NERC |
| X longitude/easting: | 138950 |
| Y latitude/northing: | 796800 |
| Coordinate reference system, ESPG code: | 27700 (OSGB 1936 / British National Grid) |
| Orientation: | Landscape |
| Size: | 236.99 KB; 1000 x 667 pixels; 85 x 56 mm (print at 300 DPI); 265 x 176 mm (screen at 96 DPI); |
| Average Rating: | Not yet rated |
| Categories: | Unsorted Images |
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