Disused workings at Craig-y-Forwyn (SJ23604800) lie just off the Offa’s Dyke Path, while to the south, at World’s End, there is an old level at SJ 2345 4775. A second level remains to the west at SJ 2300 4780, to the north of Graig-y-Adar. At the eastern extremity of the vein, a large shaft (SJ 2485 4750) known as Eglwyseg Extension is still visible.

The Eglwyseg Vein cuts east to west across the World’s End area of Ruabon Mountain, with lead mining activities occurring between 1867 and 1886. The vein runs through the Cefn-y-fedw sandstone, which overlies Carboniferous Limestone.