| P number: | P531432 |
|---|---|
| Caption: | Photomicrograph of marble. Light: PPL. Magnification: x2.5. Roadside 430 yards east-north-east of Ledbeg, Sutherland, Scotland. |
| Description: | A massive, structureless, compact, white serpentinous marble, with faint yellow patternless markings. This specimen is Cambro-Ordovician in age. BGS sample number SL 271. British Geological Survey Petrology Collection sample number S 35796. Photomicrograph details: Light: PPL, Magnification: x2.5. The rock is composed of an aggregate of shapeless interlocking grains of calcite, 0.05-0.15 mm in size. These are generally traversed by very close-set cleavage and twinning planes. In places the rock shows a mottling due to angularly patchy distribution of clear and turbid calcite. The clear patches are composed of the small grains and the turbid patches seem to be relics of large crystals in which almost submicroscopic striations (due to cleavage or twinning or both) have been produced. The striations are subparallel throughout the patch and are interrupted where new small grains with broader twin lamellae have crystallized. The orientation of the lamellae in such grains is diverse. In places narrow lines of shear are shown by granulation and parallel orientation of calcite grains and by a lining of thin serpentine flakes. Pseudomorphs of olivine in serpentine are sporadic in the rock as individual crystals or clusters. Phlogopite also is present in small flakes and aggregates, the calcite associated with which is coarser in grain than elsewhere in the rock. The rock is a marble triturated by stress. |
| Date taken: | Sun Jun 25 00:00:00 GMT 1905 |
| Photographer: | Unknown |
| Copyright statement: | Unknown |
| Orientation: | Landscape |
| Size: | 313.31 KB; 1000 x 663 pixels; 85 x 56 mm (print at 300 DPI); 265 x 175 mm (screen at 96 DPI); |
| Average Rating: | Not yet rated |
| Categories: | Unsorted Images |
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