The South Wales Mineral Railway was a railway built to serve collieries in the upper Afan Valley, and bring their output to a dock at Briton Ferry, in South Wales. It opened in stages, in 1861 and 1863. It was built on the broad gauge and had steep gradients, including a rope worked incline near Briton Ferry. Always short of money, it was worked by a coal company for some years and then by the Great Western Railway from 1908. It was absorbed by that company in 1923.