The Bwlchyddaufryn Vein, located in Carboniferous Limestone, stretches from Trinity Church to the Nant Alun cross-cut. It runs parallel and north of the Pantybuarth Vein.

Few visible workings remain, as the area has been landscaped for use as a golf course, with overgrown patches marking possible sites. The shaft recorded by the OS at SJ 2010 6450 is completely overgrown, while shaft mounds can be identified at SJ 1995 6445, SJ 1978 6443, and SJ 1985 6444.

Three additional shafts on the Bwlchyddaufryn Vein are recorded near Ffordd-hir. Further shaft and mound features are located at SJ 2120 6450 and SJ 2070 6420, while a fenced-off shaft with associated spoil remains at SJ 2030 6390.