The Engine Shaft, located at SJ 1866 6695, remains stone-lined and filled, and is now fenced off. It is believed to have been used for working the Coed Du cross-course vein. The shaft and its associated engine house are situated within a field containing numerous shallow workings. The mine was drained by a day level driven eastward to a point north of Plas Wilkin at SJ 1941 6695.

Shafts are recorded along the Garreg Boeth Vein, extending eastward from the Engine Shaft at SJ 1862 6699 and SJ 1863 6698, both positioned northwest of the main shaft. Additional shafts remain to the south of Garreg Boeth Farm at SJ 1886 6704 and SJ 1908 6706. Further workings, including shafts, are documented within Garreg Boeth Wood, Big Wood, and Round Wood, where four shafts are recorded. The mine’s sett was eventually reached by the Halkyn deep level by 1908.

The engine house, constructed from local stone, remains standing to a height of approximately 8 meters. Despite being overgrown with ivy, the beam wall and one additional wall are still intact. Architectural features include a partially blocked brick archway, likely the exit for pipes leading to the boiler house, and visible beam sockets. The structure, located at SJ 1866 6695, is thought to be an early 19th-century Cornish engine house.

Smaller workings and shafts can be observed along the vein in a wide east-west alignment, apparently terminating at shaft. These range from small linear cuts, approximately 2 meters wide, 1 meter deep, and 6 meters long, to small circular depressions presumed to be trial shafts. These depressions vary in size, typically measuring between 2 and 4 meters in diameter, 0.5 to 1 meter in height, and 0.5 meters in depth. The number of these smaller workings is too numerous to fully document at this time.

The Mwynbwll/Fagnallt lead mine operated between 1878 and 1889, working the old Garreg Boerth Vein, which runs east-west through the site. At its western end, this vein is known as the Mwynbwll Vein. The mine also intersects a north-south lode, believed to be the Caleb Bell cross-course, while the Engine Shaft is situated on the Coed Du cross-course in Carboniferous Limestone.