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[[Image:Blaenau.jpg|right|thumb|500px|The landscape surrounding Blaenau has been blighted with millions of tons of spoil. These slag heaps arose mainly as a result of 19th century mining techniques, and unfettered capitaliism.]]

[[Image:Blaenau.jpg|right|thumb|500px|The landscape surrounding Blaenau has been blighted with millions of tons of spoil. These slag heaps arose mainly as a result of 19th century mining techniques, and unfettered [[capitalism]].]]

'''Blaenau Ffestiniog''' (pronounced ''bly-now fest-inny-oc'') is the capital of the Welsh [[slate]] quarrying industry. The slate-bearing strata of Ffestiniog belong to the [[Ordovician]] or Lower [[Silurian]] systems, and are of an uniform soft blue-gray color, although the North Vein or topmost bed shows a tendency to be slightly darker. The chemical analysis of a standard Ffestiniog slate shows silica 55%, alumina 25%, iron oxide 11%, the remainder being composed of various elements of which the chief is magnesia. The lime contents - an excess of which often characterizes an inferior slate - are negligible. <ref>For a more detailed account, see: http://www.llechicymru.info/t000952.cymraeg.htm</ref>.  

'''Blaenau Ffestiniog''' (pronounced ''bly-now fest-inny-oc'') is the capital of the Welsh [[slate]] quarrying industry. The slate-bearing strata of Ffestiniog belong to the [[Ordovician]] or Lower [[Silurian]] systems, and are of an uniform soft blue-gray color, although the North Vein or topmost bed shows a tendency to be slightly darker. The chemical analysis of a standard Ffestiniog slate shows silica 55%, alumina 25%, iron oxide 11%, the remainder being composed of various elements of which the chief is magnesia. The lime contents - an excess of which often characterizes an inferior slate - are negligible. <ref>For a more detailed account, see: http://www.llechicymru.info/t000952.cymraeg.htm</ref>.