Slate quarry near Aberdovey, Wales. Opening date unknown; first mentioned on 20 July 1865. Sold in 1877 to the Frongoch Slate Quarry Company Limited. Auctioned at 11:00 am on 24 March 1881; subsequent fate unknown.
Wikipedia: https://en.wikipedia.org/wiki/Frongoch_quarry,_Aberdyfi