Area: 2.32 hectares.
A new site, listed as of national importance in the Geological Conservation Review.
The mine is a section of about 600 m on an East / West lode which has been worked for a distance of 3 km. The lode is either a double lode or one in which the mineralisation is telescoped, for tin, copper and lead minerals are all present on the dumps, which are very extensive. The dumps are almost as prolific as Wheal Gorland in the variety of secondary copper-lead minerals, but most of the mineralogical interest is centred around two areas of dumps at Dawes Shaft and Dukes Shaft. Penberthy Croft is the world type locality for at least two minerals -- connellite and bayldonite. Among other very rare minerals are carminite, plumbogummite, wroewolfite, serpierite and mansfieldite; altogether some 40 mineral species have been recorded. Penberthy Croft is the most important site in Britain for secondary ore minerals of lead, copper, and arsenic. The mineralisation is of Hercynian age.