A detailed topographic survey of part of Llanymynech Hill and of the entrance to
the Ogof Mine was carried out in June 1996 as part of an evaluation of survey methods
and site assessment for early mining sites in Wales.
No excavation was undertaken, but underground exploration led to the discovery of
a rounded (and originally hand-held) quartz hammer stone lying amongst the rubble
on the floor of the Mandible Chamber close to the blocked Lower Entrance of the Ogof.
Little more can be said of this at the moment, yet the find is suggestive of pre-Roman
and possibly pre- Iron Age mining within the area of the Ogof Gully and entrances.
Evidence for Iron Age copper metallurgy has been found within the area of the hillfort.