| P number: | P521421 |
|---|---|
| Caption: | Rock specimen of chiastolite slate. Knocknairling, 1.25 miles south-south-west of New Galloway, Kirkcudbrightshire, Scotland. |
| Description: | The sample is a pale grey coloured slate with distinct large elongate laths of the mineral andalusite on the cleavage surface. The rock will be Silurian in age. British Geological Survey Petrology Collection sample number EMC3817. Chiastolite is a term for a specific form of the mineral andalusite, where it forms elongate laths sometimes with a cruciform shape. Andalusite is one of the aluminium silicate minerals which are found in metamorphic rocks, and are used to estimate the pressures and temperatures present during metamorphic events. Andalusite is a grey, pink or slightly reddish mineral that is typical of low grade thermal metamorphism. The intrusion of the granite pluton of Cairnsmore of Fleet has resulted in a surrounding metamorphic aureole where the adjacent rocks have been altered by the great amount of heat generated by the emplacement of the granite. Away from the intrusion the effect gradually declines. Highly metamorphosed sediments occur at Knocknairling Hill, argillaceous rocks pass into andalusite-mica-schists and gritty beds become quartz-mica-schists. |
| Date taken: | 01/12/2002 |
| Photographer: | McTaggart, F.I. |
| Associate: | T.S. Bain |
| Copyright statement: | NERC |
| Additional information: | EMC3817 |
| Orientation: | Portrait |
| Size: | 245.36 KB; 775 x 1000 pixels; 66 x 85 mm (print at 300 DPI); 205 x 265 mm (screen at 96 DPI); |
| Average Rating: | Not yet rated |
| Categories: | Unsorted Images |
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