Part of the main copper mining complex, this single-celled rectangular building measures 8m east/west by 4m north/south and has walls remaining to a maximum height of 2m. Two windows and a door are located in the southern wall, and parts of the chimney and fireplace remain on the eastern gable wall. Pieces of a cast iron range have also been left in the building. Noted during an upland survey conducted by Archaeophysica during 2005-6