| P number: | P524324 |
|---|---|
| Caption: | Photomicrograph of onyx. Light: PPL, Magnification x 2. Pentland Hills, Midlothian, Midlothian. |
| Description: | The image is a photomicrograph of a thin section of an onyx which consists of a series of straight parallel bands of different colours of cryptocrystalline silica. British Geological Survey Petrology Collection sample number ED 1227. Light: PPL, Magnification x 2. Light: PPL, Magnification x 2. Onyx is a variety of chalcedony that is related to banded agate in that it consists of alternating bands of different colours, but where the bands are always straight and parallel. Onyx has long been valued as a semi-precious stone used to make cameos. At the time this rock formed in the Lower Devonian there was a widespread Caledonian calc-alkaline igneous province extending throughout Scotland that was responsible for the formation of not only the Pentlands but also the Sidlaw, Ochil and Carrick Hills. |
| Date taken: | Wed Jan 01 00:00:00 GMT 2003 |
| Photographer: | Hyslop, E.K. |
| Copyright statement: | NERC |
| Orientation: | Landscape |
| Size: | 212.83 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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