Porth Neigwl lead mine at Tan yr Allt, Llanengan, was one of several in the area and may date from the seventeenth century or earlier. The site had already closed and was marked as disused by the time of the Ordnance Survey First Edition 25in map of 1889. There are spoil tips, buildings, a shaft and other structures surviving at Tan yr Allt, and on the hillside to the south east stands a tall circular chimney (nprn 409206).
B.A.Malaws, RCAHMW, 17 July 2009.