Aberllefenni quarry is the collective name of three slate quarries, Foel Grochan, Hen Gloddfa and Ceunant Ddu, located in Cwm Hengae, just to the west of Aberllefenni, Gwynedd, North Wales. It was the longest continually operated slate mine in the world until its closure in 2003. Foel Grochan is the quarry on the north side of the valley, facing Ceunant Ddu and Hen Gloddfa on the south; all three were worked as a single concern throughout their history. Rock was mainly extracted underground, though all three quarries had open pits as well.
Braichgoch slate mine was a large slate mine located in Corris Uchaf, north Wales. It was worked continuously from 1787 until closure in 1970, apart from a hiatus in the 1900s. Most of the surface workings of the quarry were removed as part of a road widening and landscaping scheme in 1983.
The existence of a slate industry in Wales is attested since the Roman period, when slate was used to roof the fort at Segontium, now Caernarfon. The slate industry grew slowly until the early 18th century, then expanded rapidly until the late 19th century, at which time the most important slate producing areas were in northwest Wales, including the Penrhyn Quarry near Bethesda, the Dinorwic Quarry near Llanberis, the Nantlle Valley quarries, and Blaenau Ffestiniog, where the slate was mined rather than quarried. Penrhyn and Dinorwig were the two largest slate quarries in the world, and the Oakeley mine at Blaenau Ffestiniog was the largest slate mine in the world. Slate is mainly used for roofing, but is also produced as thicker slab for a variety of uses including flooring, worktops and headstones.
The Gorseddau Junction and Portmadoc Railway is a defunct Welsh tramway.
The Hendre-Ddu Tramway was a 2 ft narrow gauge industrial railway built in 1867 in Mid-Wales to connect the Hendre-Ddu slate quarry to Aberangell station on the Mawddwy Railway. It consisted of a main line 3+1⁄2 miles (5.6 km) long and several branch lines and spurs serving other quarries, local farms and the timber industry.
Narrow-gauge railways were used extensively in the slate industry of Great Britain, especially in Wales. Many quarries had internal tramways, some using many dozens of miles of track. Others had private lines that stretched from the quarry to transhipment points on local railways, rivers, roads or coastal ports.
Wrysgan quarry was a slate quarry near the village of Tanygrisiau, Blaenau Festiniog, North Wales. It was worked intermittently from the 1830s, and was worked continuously from c.1850 until 1946. Wrysgan was an underground slate quarry, which was located on a small inaccessible site, some 1,390 feet (420 m) above sea level, to the west of Cwmorthin.
The Ratgoed Tramway was a 2 ft 3 in gauge horse-worked tramway that connected the remote Ratgoed Quarry with the Corris Railway at Aberllefenni. It was 1.75 miles (2.82 km) long.
Fron-Boeth and Pant Mawr quarries were two closely related and interconnected quarries on the western slopes of Moelwyn Mawr in Gwynedd, North Wales. Pant Mawr operated from around 1850 to 1879, and was partly re-opened in 1886 when it was amalgamated with Fron-Boeth. Both quarries closed during the First World War. Finished product was transported to the slate quays of Porthmadog by the Croesor Tramway.
Cymerau quarry was a slate quarry served by the Ratgoed Tramway, a horse-worked section of the Corris Railway. It is located about half a mile north of Aberllefenni in Merioneth, North Wales, on the eastern side of the isolated Cwm Ceiswyn. It worked the Narrow Vein, the highest-quality slate vein in the Abercorris Group.
The Abercwmeiddaw quarry was a slate quarry that operated between the 1840s and 1938. It was located at Corris Uchaf about 5 miles (8.0 km) north of Machynlleth, in Gwynedd, north-west Wales. The quarry was connected to the Corris Railway via the Upper Corris Tramway which carried its products to the Cambrian Railways at Machynlleth for distribution.
The Llwyngwern quarry was a slate quarry in Wales that opened by 1828 and continued working until about 1950. The quarry is located on the western flank of Mynydd Llwyn-gwern.
Cwm Hengae is a valley that runs roughly north-west from the village of Aberllefenni in Wales. The Afon Llefenni river runs along the valley and several slate quarries occupy the valley sides. The Roman road Sarn Helen ran along the valley, connecting Aberllefenni with Dolgellau.
Mynydd Cambergi or Mynydd Cam-bergi is a mountain in southern Snowdonia, Wales. It is a summit on a long ridge between Mynydd y Waun to the north and Foel Grochan to the east. The mountain forms the north-east side of Cwm Hengae and sits about 0.5 miles (0.80 km) west of the village of Aberangell.
The Broad Vein Mudstone Formation is an Ordovician lithostratigraphic group in Mid Wales. The rock of the formation is silty mudstone, intensely bioturbated in places. It varies in colour from a pale to a medium blue. This formation has been commercially quarried as slate in several locations along its length. The formation is between 400 metres (1,300 ft) and 560 metres (1,840 ft) thick and runs from Dinas Mawddwy south-west to Cardigan Bay at Tywyn.
The Prince Llewellyn quarry was a slate quarry that stands on the west side of the Lledr Valley, ENE of Dolwyddelan. It was worked from around 1820 to 1934.
Ty'n-y-bryn quarry was a slate quarry that was worked from the 1840s to about 1914. It stands on the south-east edge of Dolwyddelan.
Rhiw-goch quarry was a slate quarry that was worked from the 1860s to 1908. It stands on the north side of the Afon Lledr, on the opposite side of the valley from Pont-y-Pant railway station.
The Penmachno quarry was a slate quarry near Cwm Penmachno, Conwy, North Wales. It was directly below the Rhiwbach Quarry. It was worked between 1818 and 1962.
The Cwm Ebol quarry was a slate quarry about 1 mile (1.6 km) north west of the village of Pennal in Mid Wales. It operated from about 1860 to about 1906. It was the last Welsh slate quarry connected only to a trans-shipment point instead of directly to a railway.
