Aberllefenni quarry, Slate quarry in Gwynedd, Wales
Aberllefenni quarry consists of three separate mining areas named Foel Grochan, Hen Gloddfa, and Ceunant Ddu spread across the Cwm Hengae valley. The different sites reveal various layers and working methods from different periods of slate extraction.
Extraction began around 1500 when slate was used to roof the nearby manor house Plas Aberllefenni. From there the site developed into one of Wales' major slate-producing centers and shaped the region's economy for centuries.
The slate extracted here displays a deep blue color that craftspeople still value for traditional roofing work. Local residents regard this place as a symbol of their mining heritage and part of Wales' slate-working tradition.
Access to the site has been enabled by infrastructure that once transported slate from the valley to surrounding towns. Today the location operates as a museum where visitors can explore the quarry on foot and view equipment from its working years.
With over five centuries of continuous operation until its closure in 2003, this was the longest-running slate mine in the world without interruption. This remarkable span of time makes it an extraordinary example of industrial persistence.
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