P number: | P527924 |
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Caption: | Photomicrograph of Loch Tay Limestone. Light: XPL. Magnification: x2.5. Old quarry 550 yards west of Dalveich Farm, Loch Earn, Perthshire, Scotland. |
Description: | Dark grey, saccharoidal, crystalline limestone with broadly spaced micaceous laminae. This specimen is Dalradian Supergroup (Precambrian) in age. BGS sample number SL 1. British Geological Survey Petrology Collection sample number S 34426. Photomicrograph details: Light: XPL, Magnification: x2.5. The rock is composed of twinned calcite grains up to 1.5 mm long, subordinate quartz, accessory graphite, iron ore (probably pyrite), colourless and pale brown micas and occasional large plates and small particle-filled grains of albite-oligoclase. Trains of graphite and elongation of calcite grains show some degree of schistosity. In some places the limestone is mottled dark grey and white and schistose with micaceous partings producing a thinly flaggy fracture. Here it is composed of elongated grains of calcite, up to 3 mm long, sieved with quartz, albite and opaque granules, foliated with granoblastic, clean calcite of about 0.5 mm grain. Quartz and albite are abundant along laminae of white mica. Some pyrite is present, and possibly graphite also. |
Date taken: | Sun Jun 25 00:00:00 GMT 1905 |
Photographer: | Unknown |
Copyright statement: | Unknown |
Orientation: | Landscape |
Size: | 339.81 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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