http://earthwise.bgs.ac.uk/index.php?action=history&feed=atom&title=File%3AP519604.jpg 2026-07-03T03:43:49Z Revision history for this page on the wiki MediaWiki 1.42.3 http://earthwise.bgs.ac.uk/index.php?title=File:P519604.jpg&diff=31768&oldid=prev 2017-07-29T15:21:44Z

<p>User created page with UploadWizard</p> <p><b>New page</b></p><div>=={{int:filedesc}}==<br /> {{Information<br /> |description={{|1=Specimen of roofing slate from Aberfoyle Slate Quarries, Perthshire, Scotland. Greenish grey slate sample with reflective cleavage surface showing strong ribboning. The specimen is of Precambrian, Dalradian age. British Geological Survey Petrology Collection sample number EMC 5779. Ribboning is an old term used by the quarrymen to describe the presence of parallel bands on the slate surface, caused by the intersection of the original bedding planes. The slaty cleavage which produces the ability of a slate to split into thin layers is entirely a metamorphic feature, caused by the growth of new&#039;platy&#039;minerals such as mica and chlorite and the recrystallization and alignment of original minerals such as quartz and feldspar. In the Highland Border belt, records of the Aberfoyle Quarries extend back for 250 years, while a quarry at Luss on Loch Lomond is recorded as having been in operation as far back as the 15th century. On Arran slate working was first recorded at Loch Ranza in 1773. Specimen size: 15x15cm. P519604.}}<br /> |date=2017-07-29 15:59:45<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>

Scotfot