http://earthwise.bgs.ac.uk/index.php?action=history&feed=atom&title=File%3AP519663.jpg 2026-07-03T01:51:17Z Revision history for this page on the wiki MediaWiki 1.42.3 http://earthwise.bgs.ac.uk/index.php?title=File:P519663.jpg&diff=31789&oldid=prev 2017-07-29T15:22:15Z

<p>User created page with UploadWizard</p> <p><b>New page</b></p><div>=={{int:filedesc}}==<br /> {{Information<br /> |description={{|1=Easdale Slate showing crenulation and pyrite crystal, Easdale Island, Argyllshire, Scotland. The image is a detail of the cleavage surface of a slate showing a strong crenulation and pyrite crystals. The specimen is of Precambrian, Dalradian age. British Geological Survey Petrology Collection sample number EMC 5735. A slaty cleavage is formed by fine-grained clay minerals and micas aligned on a single set of closely spaced parallel planes of fabric. This governs the splitting properties and thickness of a slate tile. Other minerals such as quartz and feldspar act as fillers giving the slate bulk and strength. Too much of these make a slate too thick with a coarse surface finish; too little and it is soft with low strength. In thin section high quality slates show stretched and flattened quartz and feldspar grains along the cleavage, commonly with `beards? of mica and chlorite growing from the ends of these grains. Parallel to this direction the rock splits very readily, whilst at right angles to it the rock possesses great strength which may be compared to the bonding of bricks in a wall. P519663.}}<br /> |date=2017-07-29 16:00:09<br /> |source=British Geological Survey<br /> |author=British Geological Survey<br /> |permission=<br /> |other versions=<br /> }}<br /> <br /> =={{int:license-header}}==<br /> {{subst:Custom license marker added by UW}}<br /> {{BGS}}<br /> <br /> [[Category:Uploaded with UploadWizard]]</div>

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