This structure was built to mark the entrance to the old quarry, it has been transformed over the last 10 years into a very attractive nature reserve.
Most of the structure appears to be sand stone, but the stone in this image is a piece of the mined whinstone ( Basaltic Andesite) as with all the Whinstone boulders and cobbles and smaller pieces that remain in the quarry plantation, it attracts a magnet note the green, red, and pink magnets stuck to the stone.