The three large bays of the calcining kilns are about 90m long and can be easily seen from all around the valley.
The iron ore mined here was carbonated which required calcining before smelting.
In one of the bays the retaining wall which looks to have been anchored with large wires has collapsed, the faces of wall were once lined with wrought iron which was removed when the mine was abandoned.
Ironstone and coal would loaded into the top and calcined ore drawn out from the bottom, It has been estimated that each kiln could produce around 2000 tons of calcined ore a week using about 80 tons of coal. In a more complete bay the top courses of fire bricks are balancing precariously on small pins.