In 1951 Professor F W Shotton of Birmingham University identified the source of the rock used for shafthole battle-axes and axe-hammers as picrite which had been quarried from Corndon Hill. Production sites of stone axes and shafthole implements have been grouped by petrology and the Hyssington/Corndon Hill implements are known as Group XII. As the production of these implements in the Late Neolithic and Early Bronze Age did not employed the same flaking techniques as stone axes, which leave recognisable flaking debris, the site or sites of the Corndon Group XII implements production will be very much harder to identitify. However the Clwyd-Powys Archaeological Trust did excavate several small quarry depressions in 2008, but only found evidence of fairly recent disturbance. A stone slab with striations which was suggested was an example of Neolithic art, could equally well have been early plough marks