A group of open-cast pits is situated on an east-west porphyritic (elvan) dyke south of the summit of Castle-an-Dinas. While two of the pits have been filled, one remains with a depth of 40 feet. Between 1870 and 1873, the mine yielded 24 tons of black tin. Although prospected in the 1970s, the values were deemed too erratic for further development. This site represents a cassiterite dissemination deposit. Also adit.

1836-1837 1851-1852 1870-1873