Chalcedony from selected localities.
UK | |
| Ref: Dunham, K. C., 1990, Geology of the Northern Pennine Orefield Vol I - Tyne to Stainmore 2nd Ed. British Geological Survey, London, pp 221, 224 - 226. |
UK | |
| Ref: Dunham, K. C., 1990, Geology of the Northern Pennine Orefield Vol I - Tyne to Stainmore 2nd Ed. British Geological Survey, London, pp 221, 224 - 226. |