Ironstone was mined briefly from Tyllau Mwn (nprn 527249) in 1770, and again on a more modest scale in 1878 and 1910. The shaft was sunk in 1770 and was described as 5 yards deep. This is one of the 2 deep pits separated by a ridge, measuring in total 18m N-S x 6m. The N pit is 1.7m deep, with grass and some exposed rock. The former shaft on the S side is 3.5m deep with exposed bedrock on the S and E sides, and a stone platform to the W (NPRN527321). Running S is a narrow trench, 10m long, which then turns SW and continues for 15m down the slope.
Recorded as part of RCAHMW Uplands Initiative Project, W B Horton, H&H, 13/11/2012.