Slate mining on Anglesey
One doesn’t immediately think of Anglesey as a location for slate mining, certainly not in the vicinity of Snowdonia with its massive slate quarries at Penrhyn, Dinorwic and mines at Blaenau Ffestiniog. But Anglesey does have a very large outcrop of Ordovician rock, most however buried under glacial and post glacial sediments.
Coastal outcrops are noticeable at Lynas on the east coast and on the west coast, especially in the context of the Carmel Head thrust, a low angle fault that has moved Cambrian and Precambrian rocks over the Ordovician. In these two localities, the Ordovician rocks are of modest quality slate and have been quarried.
The most obvious, the North Anglesey (Point Aelianus) Slate and Slab Quarry (known locally as Chwarel Sglaets) at Llaneilian commenced production in February 1870 under a company set up by men from Yorkshire and Manchester. Shareholders were asked to provide further investment in 1874-1876 to “put the company in a permanently remunerative state”. Despite the glowing prospectus, the gleaming reports from various quarrying authorities from Caernarfonshire, and the employment of John Hughes from the Dinorwig Quarry, the great expectations were not realised. The plan to create ‘Port Dinorben’ for the export of slate had been shelved by 1872, and carts were used to carry the slate to Porth Eilian. In 1873 the 10 workers had discovered a lode of copper and another level was planned. But interest in the company shares had waned and the directors were decrying the fact that no suitable land was available to build slate dressing sheds. Up to June 1873 1,940 first grade slates, 480 second grade slates, and 2,700 moss slates had been produced [source]
Coflein includes the following details
“The slate quarry at Tyllau Duon, Llanelian is a spectacular series of cliff-face workings on the north-east coast of Anglesey. The quarry was already portrayed as ‘Old Quarry’ when the Ordnance Survey first-edition 25-inch map was published in 1889. Visible remains include small working faces, some buildings and traces of an access track. But the most notable feature is a flight of steps cut into the cliff to give access from the sea. There is some indication that underground working was attempted” [source]. A reference is given [A.J.Richards, A Gazetteer of the Welsh Slate Industry (1991), p.25]. The side by side map/satellite website gives a clear picture of these workings which can be seen from the coastal footpath walking south from Porth Eilian.
Llanflewyn Slate and Slab Quarries Co. Ltd was formed at about the same time, working on land in Llanflewyn leased from the Bulkeley estate” [source: JISC Archives hub 23 documents are held at Anglesey Archives] , which was producing moss slates in 1864 and a new lease was taken out in 1875 with permission to build an engine house, stores, worker’s cottages, tramways, shafts, levels and adits. The visions of prosperity were not realised though.[source]
