NR8829 : Beach Boulder

taken 6 years ago, near to Blackwaterfoot, North Ayrshire, Great Britain

Beach Boulder
Beach Boulder
This large boulder on the beach has formed from a broken-off fragment from the central, more silica-rich, part of the Drumadoon Sill. It contains a myriad of crystals which formed in the magma chamber before the magma was emplaced to form the sill. Most of the crystals are of feldspar, some of them showing the typical angular shape of that mineral, while others are round and show concentric zoning, caused by changes in the geochemistry from centre to surface of the crystal. The enclaves with fewer crystals are blobs of more basaltic magma caught up in the magma flow, and some of the blobs also contain crystals. There is a geological explanation, but it is long and involved and requires complicated chemistry and drawing lots of diagrams, so I'll have to ask you to take my word that it is a very unusual and interesting rock.
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NR8829, 29 images   (more nearby )
  (find more nearby)
Date Taken
Saturday, 15 September, 2012   (more nearby)
Saturday, 29 September, 2012
Geographical Context
Geological interest 
Subject Location
OSGB36: geotagged! NR 8843 2910 [10m precision]
WGS84: 55:30.5824N 5:21.1290W
Camera Location
OSGB36: geotagged! NR 8843 2910
View Direction
NORTH (about 0 degrees)
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