| P number: | P519868 |
|---|---|
| Caption: | Photomicrograph of sandstone from Clashach Quarry, Morayshire, Scotland |
| Description: | The image is a photomicrograph of a thin section of sandstone, taken using a relatively high-powered lens in order to examine the detailed mineral and pore structure of the rock. The specimen is of Permian age. British Geological Survey Petrology Collection sample number MC 5799. The sandstone is composed of subround grains of quartz, clear in thin section. Each grain has a thin overgrowth of quartz which is intergown with adjacent grains, forming a silica cement. The original edges of the rounded quartz grains can be seen as a faint line beneath the overgrowths. Quartz (also known as silica) is one of the most durable minerals, and a silica cement produces some of the hardest sandstones. The pore spaces in this part of the thin section contain opaque or black iron oxides. This mineral has been precipitated in the porosity having been transported through the sandstone whilst dissolved in groundwater. It is these iron oxide minerals that give Clashach sandstone its distinctive orange-brown colour. The colour is highly variable, depending on the presence or absence of these iron oxide minerals in the porosity. |
| Date taken: | Wed Jan 01 00:00:00 GMT 2003 |
| Photographer: | Bain, T.S. |
| Copyright statement: | NERC |
| Orientation: | Landscape |
| Size: | 147.71 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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