Bangley Quarry
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Condition (NatureScot)
| Unit | Feature | Condition | Area (ha) | Assessed |
|---|---|---|---|---|
| F1 | Mineralogy of Scotland | Unfavourable Declining | — | 2017-01-11 |
Geology & landscape
Mining / Industrial: Quarry · Geological Period: Carboniferous
Landscape processes: Volcanic / Igneous
Description
BANGLEY QUARRY Bangley Quarry is located approximately 2km north-west of Haddington in central East Lothian. Quarrying has exposed lavas of Carboniferous age, principally trachytes of quartz-banakite type, which are characterised by zoned feldspar phenocrysts. The mineralogical interest of the site, however, is focused on a trachybasalt dyke, which also carried phenocrysts, and cuts vertically through the lava sequence, oriented approximately north-south. The dyke is about three metres wide, with a closely-spaced horizontal jointing which helps distinguish it from the more massively jointed lavas. The dyke has long been noted for the presence of large (up to 5cm) clear crystals of sanidine feldspar, which show euhedral outlines and Carlsbad twinning. Sanidine, which is the high-temperature form of potassium-feldspar, is unstable at lower temperatures. Its presence therefore indicates metastable preservation and is of rare occurrence, typically attributed to rapid cooling of the host rock. The Bangley quarry sanidine specimens are the highest quality in Britain.