Long sett East of Prosper United. In 1954, Sir Arthur Russell collected linarite, galena, and native copper from a dump located in the western part of the Trevarthen Mine sett. It’s worth noting that Trevarthen Mine is incorrectly labeled as such in Greg & Lettsom (1858) and Hall (1868). The sett stretches east-west for approximately 1200 meters from Long Road, effectively dividing it from Penberthy Croft in the east to Trevarthian Farm in the west. Evidence of numerous shaft collars and tips can be found across the sett in a swath about 400 meters wide. Galena, arsenopyrite, and chalcopyrite are abundant, as are many secondary minerals.