The assay house was the laboratory of the Assay Master, whose job was to analyse ore samples to determine their lead and silver content, and thus set the prices paid to the miners. For 2007 it has been converted into a bunkhouse, sleeping up to 12 people in double bunks, in two upstairs bedrooms. There is a kitchen / dining room downstairs. The bunkhouse is fully heated, has hot water and showers, and a small kitchen / dining room on the ground floor.