Chwarel Ddu
Caernarfonshire, United Kingdom
Chwarel Ddu quarry was the earliest slate quarry in the Lledr Valley. It was working before 1810, and continued in sporadic operation until the late 1920s. It is about 0.5 miles (0.80 km) west of Dolwyddelan, just beneath Dolwyddelan Castle.
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