| P number: | P552968 |
|---|---|
| Caption: | Calcareous sandstone. Allt na Teangaidh, 500 yards north-east of Balmeanach, Gribun, Mull. Argyll. |
| Description: | A dark, fine-grained, rough rock, containing many small aggregates of finely divided pyrite. Composed of angular grains of quartz and subordinate, but abundant albite, in a matrix of brownish calcite which tends to form large irregular grains enveloping several grains of quartz. Orthoclase is an accessory constituent, as are muscovite and scarce phosphatic fossil fragments and grains of garnet, zircon and rutile. Thin-walled shell fragments are common. Pyrite and carbonaceous matter are abundant. The former is mostly in small grains and streaks, but locally forms large lumps enclosing many quartz grains. The carbonaceous matter is black in reflected light, brown in transmitted light and in some larger fragments looks like wood. Dolomite appears in minor amount as rhombs of 0.1 mm size, in the calcite, and may be a very early if not a primary constituent. Limestone, arenaceous, fossiliferous, poikilocrystallic. SL0227. Britrocks S35085. Magnification x40. Light PPL. |
| Date taken: | Wed Jan 21 00:00:00 GMT 2004 |
| Photographer: | Sutherland, A. |
| Copyright statement: | NERC |
| Additional information: | Description from: Limestones of Scotland: chemical analyses and petrography. Edinburgh : HMSO, 1956. |
| Orientation: | Landscape |
| Size: | 365.27 KB; 1000 x 750 pixels; 85 x 64 mm (print at 300 DPI); 265 x 198 mm (screen at 96 DPI); |
| Average Rating: | Not yet rated |
| Categories: | Unsorted Images |
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