Rock-crusher house and wheel-pit at Llywernog Mine

The rock-crusher house and wheel-pit at Llywernog Mine is a Grade II listed structure made of rubble stone, featuring a restored upper floor and a slate pyramid roof. The building has a square plan and is built into a steep bank. The south front includes a 20th-century lean-to made of corrugated iron and timber on the ground floor, with a single six-pane window located under the eaves above. The west side also has a similar six-pane window under the eaves, along with a broad doorway to the right, which has a timber lintel and iron rail tracks leading inside. The rear of the building features a stone ramp leading down to a gabled doorway that breaks the eaves at the first floor, used for bringing in ore.

Attached to the right of the rock-crusher house is a large raised wheel-pit made of rubble stone, which projects forward and includes a restored end wall with a blank roundel made of yellow brick. There is also a brick-headed door on the east side. Above these features is a slate sill course, likely indicating the top of the 1861 wheel-pit designed for a 40-foot (12.2 meters) wheel, which was raised approximately 1.5 meters in 1874-1875 to accommodate a 50-foot (15.25 meters) wheel. Cast-iron brackets for the waterwheel can be found on the top of the wall. The pit is deep.

The interior of the building has been partially restored and includes beams that support a mid to late 19th-century iron roll-crusher, which was relocated from the Llawrcwmbach mine.