A lead mine is shown with a small building with a tall chinmey (Cornish enginehouse, see PRN 22015, Gwynedd Archaeological Trust?) on an historic chart. The mine is also shown as a line of five small circles (excavations/shafts) on Lewis Morris' early chart for St Tudwals Road.

Sources include:
Historic Admiralty Chart 1505_A8 RCAHMW digital collections sourced from the UK Hydrographic Office and first published in 1843
Morris, L, 1748, Plans of Harbours, Bars, Bays and Roads in St George's Channel, plate 13

Maritime Officer, RCAHMW, April 2014