Pump Engine House on Site of Wheal Uny Mine at SW 695 408

The pump engine house on the site of Wheal Uny Mine is a derelict structure, likely built in the later 19th century. It is constructed from dressed granite blocks and killas rubble, featuring a bob wall made of massive rectangular blocks. The window arches are made of brick, and there is a brick upper stage to the chimney, which is currently roofless. The building has a rectangular plan aligned on an east-west axis, with the bob wall located to the west and a chimney attached at the southeast corner.

This large building consists of three stages set back over a plinth, which is exposed on the north side due to the sloping ground. It includes round-headed openings, one of which is an unusual tall two-stage slot in the bob wall that extends from ground level, with the driver's window positioned in the upper part. There is also a large cylinder door in the rear wall. The tapered cylindrical chimney lacks a cornice on the stone stage, and the top of the brick stage is missing.

Historically, the mine was operational from before 1800 and employed over 400 workers in the 1860s. It produced tin from the Great Flat Lode and had reached a depth of 244 fathoms by the time it closed in 1893. The pump engine house is part of a prominent and attractively located group, visible from the remains of Basset Mines at Carnkie and Carn Brea.