| P number: | P527956 |
|---|---|
| Caption: | Photomicrograph of Tayvallich Limestone. Light: PPL. Magnification: x2.5. Quarry 270 yards south-east of Baluachraig, one and a quarter miles south by west of Kilmartin, Argyllshire, Scotland. |
| Description: | Dark grey, moderately crystalline limestone, containing numerous pebbles of vitreous quartz, pink feldspar and dark red material. This specimen is Dalradian Supergroup (Precambrian) in age. BGS sample number SL 125. British Geological Survey Petrology Collection sample number S 34573. Photomicrograph details: Light: PPL, Magnification: x2.5. In thin section, irregular areas of brownish oolite are seen to pass into a mosaic of clearer recrystallized calcite. Grains and aggregates of quartz and rounded crystals of microcline reaching up to 3 mm in length are numerous. The dark red pebbles appear to be microcline with much haematitic impregnation. The quartz probably originated as pebble grains, but shows considerable recrystallization. This can be observed as rims of regrowth, the old outline being marked by a zone of fine mineral matter, by intercrystallization of the grains among the new calcite and by partial inclusion of broken ooliths in quartz. The feldspars appear to have been pebbles in the oolitic limestone but are now bordered by a thin zone of recrystallized calcite where contact with oolitic rock would be expected. It may be invaded by calcite tongues and permeation aggregates of limonite and calcite. A little muscovite and albite, probably detrital, are present. Carbonaceous granules are disseminated in parts of the oolitic rock, trains of them being cut off against recrystallized calcite. Carbonaceous matter also occurs in streaks along small and irregular slip traces. |
| Date taken: | Sun Jun 25 00:00:00 GMT 1905 |
| Photographer: | Unknown |
| Copyright statement: | Unknown |
| Orientation: | Landscape |
| Size: | 348.67 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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