| P number: | P527036 |
|---|---|
| Caption: | Photomicrograph of marble from Iona Marble Quarry, Iona, Argyllshire, Scotland |
| Description: | The image is a detail of a thin section of the Iona marble under crossed-polarized light. The specimen is of Precambrian age. British Geological Survey Petrology Collection sample number S 71091. This detailed image has two mineral components. The brightly-coloured grain is a single large flake of muscovite white mica. It contains several strong cleavage traces, characteristic of micas. The bulk of the Iona marble is composed of wintergreen equigranular grains of calcite, which are darker grey-brown in the image. The Iona marble has a variable composition. It is mainly calcite, but also contains white mica, olivine, serpentine and pyroxene. Where pure calcite the rock is white in colour, but the presence of the other minerals (impurities) give the Iona marble its distinctive appearance. The presence of altered olivine and serpentine produces a characteristic mottled green colour. The presence of muscovite gives a 'glitter' effect to the rock, producing the distinctive variety called 'Iona Silverstone'. |
| Date taken: | Sun Jun 25 00:00:00 GMT 1905 |
| Photographer: | Unknown |
| Copyright statement: | Unknown |
| Orientation: | Landscape |
| Size: | 375.47 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: | Best of BGS Images/ Rocks and minerals under the microscope |
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