Gillow State Quarry is a small, disused slate quarry between Tintagel and Trebarwith on the north coast of Cornwall, South West England.
The quarry site is at the foot of a steep coastal slope just north of St Materiana's Church in Tintagel and just to the west of the South West Coast Path.
The quarry workings extend from sea level around 40m to the top of the cliff.
The terracing where the slate has been worked can still be seen, as well as some platforms for whims and the remains of what might have been tool sheds.
The quarry provided a source of Upper Devonian slate and Lower Carboniferous slates of a greyish green colour used predominantly for roofing.