Two shafts at SJ 2160 5730, which may have been trial workings at the eastern end of the Westminster Vein. The site is located north of the Llanarmon workings at SJ 2170 5680.

The Black Mountain Lead Company operated on the sandy limestone outcrops of Mynydd Du between 1888 and 1892. The mining operations were likely centered around the Westminster Vein, which extends through the region.