Large pit working with tunnels, buildings, workshops, infirmary, inclines, drum houses.***

The main pit is the amalgamation of two separate workings: Ellen and Eureka. There are also two smaller pit workings to the south and east.

Opened in 1816 by William Turner who owned the Diphwys Casson quarry in Blaenau. £20,000 investment by the Darbishire Company in 1862 to expand the quarry bore limited fruits, just 500 tons being produced in 1871. Direct management control by William Darbishire increased production to 8,000 tons in 1882.

The last of the Nantlle quarries to produce slate, it officially closed in 1979.

The site is still nominally at work, reprocessing tip material, but access by locals is tolerated.

One Blondin tower still stands. At least three Blondin control systems in good condition in three separate buildings.