Pen-y-Bryn mine is situated on Halkyn Mountain, which was once one of the most important lead and zinc orefields in Wales. It is principally known for its lead mines. It is thought that the mining of metal ores in the area began in the Bronze Age, the earliest workings probably being relatively shallow surface workings, or bell-pits or open-cuts along the line of a vein of ore. There is more certain evidence of mining for lead and silver following the Roman conquest. Mining was still being carried out on a significant scale during the middle ages. More intensive workings began in the 17th century.

The gradual expansion of the industry and the need for higher levels of capital investment led to the replacement of small mining ventures by large-scale mining companies during the course of the 19th century. By the late 19th century Flintshire as a whole became the most productive mining area in Wales, but the end of the 19th century saw a decline in the mining industry due to competition from abroad. During the First World War, the Ministry of Munitions provided loans to stimulate the industry. Mining was suspended during the Second World War, but subsequently recommenced with a number of concerns which combined the mining of lead ore with the quarrying of limestone for agricultural purposes. The large-scale operations of the Halkyn District United Mines (the amalgamation of nine former mining companies) were centred for a period around the Pen-y-bryn Shaft on Halkyn Mountain. Small-scale mining operations continued until the 1970s, the head frame at Pen-y-bryn being finally dismantled in 1987.

Few mine buildings or other above-ground structures have survived, as a result of natural decay as well as a deliberate policy of clearing away derelict buildings.

Lead mining and quarrying features are variously depicted by OS mapping:
County series 1st ed. (Flint. IX.6 1875) depicts old workings;
County series 2nd ed. (1899), depicts Pen-y-Bryn mine in use;
County series 3rd ed. (1912), depicts New North Halkyn Mine in use.
Current mapping depicts quarry.

Reference:
Clwyd-Powys Archaeological Trust report: Historic Landscape Characterisation: Holywell Common and Halkyn Mountain, 2000.