Brockie Quarry began operation in the 1870s and closed in 1888, another similar quarry operated at the Deer Park, above the village of Ballintoy, if you look up behind the houses you will see the scree slope of tailings from the quarry. Brockie Quarry was cut and blasted into Knocksoghey Hill and the extracted dolerite rock was then worked by hand into sett stones which were flat-topped unlike cobblestone, these were then exported for use in city streets and pavings. The quarry overlooks the turning circle and access entrance to the path for the rope bridge, just above the large limestone kiln.

The quarry extended for 170 metres and would have originally had work buildings and shelters, the scree slope of tailings produced in the manual task of shaping sett stones runs down from the quarry floor to the near the turning circle. At one time the quarry run by the Eglinton Chemical Company employed over 100 men in the production of sett stones which were exported and went to pave growing cities in England, Scotland, and Wales, some also went to Wexford. At its peak, the combined workforce of Larry Bane and Brockie quarries was 150 men on total. When the quarries opened experienced Welsh quarrymen were employed to work here.