Coity Quarry was opened before 1844 to supply Pennant Sandstone for building the Blaenavon Iron Company's new houses and proposed Forgeside works. The incline for carrying the stone down the side of Coity Mountain descends from 518m to 381m at a gradient of 1 in 7. It was worked by a self-acting winding drum built of cast iron which survives in the quarry. The upper parts of the incline fell out of use by about 1880, but the lower part continued to be used to carry coal from the level below and Coity Pit to the coke ovens at Forgeside. The scheduled area includes the whole of the quarry and its waste tips, and the line of the incline to the Big Pit fence.
Source: Cadw scheduling description of 04. 2000 F.Foster/RCAHMW 03. 2006